JP5273198B2 - Optical transmission equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration in transmission quality on a network system in which an intensity-modulated optical signal and a phase-modulated optical signal are mixed. <P>SOLUTION: The invention relates to an optical transmission device for relay-transmitting, through a transmission line, wavelength multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal, including: demultiplexers 51, 53, 54 for demultiplexing the inputted wavelength multiplexed signal into a first wavelength demultiplexed signal and a second wavelength demultiplexed signal; a detour sending section 54 for sending the demultiplexed first wavelength demultiplexed signal to a detour; and wavelength multiplex-relaying sections 51-53 for wavelength multiplexing and relaying the first and second wavelength demultiplexed signals. Further, the optical transmission device includes a function for selectively blocking transmission of either the intensity-modulated optical signal or the phase-modulated optical signal from the first and second wavelength demultiplexed signals. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical transmission device suitable for use in a wavelength division multiplexing optical communication system.

  Currently, wavelength division multiplexing (WDM) transmission technology using intensity modulated optical signals (On-Off Keying) of several tens of wavelengths such as 2.5 Gbps and 10 Gbps is used in land transmission systems such as access network systems, metro network systems, and long-distance network systems. And in submarine transmission systems. The development of elemental technologies and devices is also accelerating for the 40 Gbps WDM transmission system, which will soon be put to practical use, but the transmission distance and frequency utilization efficiency equivalent to those of the 10 Gbps system are required.

  As means for realizing this 40 Gbps WDM transmission system, for example, optical duobinary (Optical Duobinary), CS-RZ (Carrier Suppressed-Return to Zero), DPSK (Differential Phase Shift Keying), DQPSK (Differential Quadrature Phase-Shift Keying), etc. Research and development of modulation systems is active. These modulation methods are part of the frequency utilization efficiency, optical signal-to-noise ratio (OSNR) tolerance, and non-linearity tolerance compared to the NRZ (Non Return to Zero) modulation method that has been applied to systems of 10 Gbps or less. Or, since all are excellent, it is a promising modulation technique as means for realizing a 40 Gbps WDM transmission system.

  Among them, the DQPSK modulation method is a method in which two bits per code are simultaneously transmitted by performing four-level phase modulation on light of one frequency channel. This method requires only half the pulse repetition frequency, ie, the code transmission rate (eg, 20 GHz) relative to the transmission data rate (eg, 40 Gbps), so the signal spectrum width is about half that of the conventional intensity modulation method. It is excellent in terms of frequency utilization efficiency, chromatic dispersion tolerance, optical device transmission characteristics, and the like. For this reason, in the field of optical transmission systems, application of a phase modulation method typified by a DPSK modulation method and a DQPSK modulation method has been actively studied.

  A WDM transmission system using an intensity-modulated optical signal such as 2.5 Gbps or 10 Gbps widely used in various systems can be enhanced by increasing the number of wavelength multiplexing. For example, since a C-band optical amplifier has a signal light band of about 32 nm, a maximum of 40 waves can be transmitted when the wavelength interval is 100 GHz (about 0.8 nm). The WDM transmission system itself is capable of transmitting 40 waves (channels), but the operator gradually increases the number of wavelengths used depending on the operation status of the network.

  However, as described above, when the number of wavelength multiplexing is increased to enhance the system, the wavelength interval becomes narrower, the amount of walk-off between wavelengths decreases, and the mutual phase, which is a nonlinear effect between wavelengths, The influence of modulation (XPM: cross phase modulation) increases. XPM is a phenomenon in which the refractive index of an optical fiber changes in proportion to a change in the intensity of an optical signal having a certain wavelength, and phase modulation is applied to an optical signal having another wavelength.

  42 (a) to 42 (c) are conceptual diagrams showing the phenomenon of cross-phase modulation by optical pulses. In FIG. 42A, λ1 and λ2 are optical pulses of two different wavelengths, and the speed of the optical pulse of λ1 is faster than the optical pulse of λ2 due to the dispersion characteristics of the propagating optical fiber. When the two optical pulses propagate in the optical fiber, the λ1 optical pulse travels faster than the λ2 optical pulse, so that the rising portion of the λ1 optical pulse is the λ2 optical pulse as shown in FIG. It begins to overlap with the falling part.

  At that time, the falling portion of the optical pulse of λ2 undergoes a phase shift by the red chirp induced at the rising portion of the optical pulse of λ1. Further, when the transmission of the optical pulses of λ1 and λ2 proceeds, as shown in FIG. 42C, the optical pulse of λ1 extracts the optical pulse of λ2, and the falling portion of the optical pulse of λ1 is λ2 It overlaps with the rising part of the light pulse. At this time, the rising portion of the optical pulse of λ2 undergoes a phase shift due to the blue chirp induced at the falling portion of the optical pulse of λ1.

  43 (a) to 43 (d) are diagrams for explaining the principle that residual chirp occurs due to the influence of cross-phase modulation that occurs in the relay section. As shown in FIG. 43 (a), when transmission line fibers 210 having positive dispersion values are connected in a plurality of stages via a plurality of lumped amplifiers 220, as shown in FIG. Light transmitted through the transmission line fiber 210 between the two centralized amplifiers 220 has a relatively large signal light power immediately after output from the centralized amplifier 220, but attenuates with transmission (first relay section). ). Then, when it is input to the next centralized amplifier 220, it is again amplified to a relatively large signal light power and sequentially transmitted through the downstream transmission line fiber 210, but here again attenuates along with the transmission (No. 1). 2 relay sections).

Now, the relay interval between the two lumped amplifiers 220 in FIG. 43A is 100 [km], the chromatic dispersion in the vicinity of the signal light wavelength is 2.5 [ps / km / nm], and the signal wavelength interval is 0.5. The transmission rate is 8 [nm] and 20 [Gbit / s]. At this time, the delay amount caused by the wavelength dispersion of the signal light of the adjacent wavelength can be expressed by the following equation, where D is the wavelength dispersion, L is the transmission distance, and Δλ is the wavelength interval.
Delay [ps] = D [ps / km / nm] * L [km] * Δλ [nm] (1)
From this equation (1), if the wavelength multiplexed signal light is propagated by 25 [km], the delay amount between adjacent wavelengths is 2.5 [ps / km / nm] × 25 [km] × 0.8 [nm] = 50 [ps], which means that the bit period of a signal with a transmission rate of 20 [Gbit / s] is 50 [ps], so that adjacent optical pulses are delayed by 1 bit.

  That is, when a light pulse of adjacent wavelengths λ1 and λ2 (see FIGS. 42A to 42C) is about to collide at a point immediately after the output from a certain concentrated amplifier 220 (coordinate 0 [km]). In this case, red chirp and blue chirp are generated once each while 25 [km] is transmitted. That is, the delay amount is 2.5 [ps / km / nm] × 100 [km] × 0.8 [nm] = 200 [ps] during transmission of the relay section 100 [km], and adjacent optical pulses are transmitted. Is delayed by 4 bits, and blue chirp and red chirp are generated four times each. For example, when the optical pulse of λ2 propagates through the transmission line fiber 210 of 100 km, it arrives with a delay of 4 bit times from the optical pulse of λ1.

  Here, it is assumed that the signal bit patterns of two different adjacent wavelength signals λ1 and λ2 are a series of “1”, and the mutual phase modulation between the two adjacent wavelengths λ1 and λ2 is considered. At this time, the wavelength multiplexed signal light is amplified to a desired optical level by the lumped constant optical amplifier 220 and then transmitted through the section of the transmission line fiber 210 at the next stage. While transmitting the section of the transmission line fiber 210, the cross phase modulation effect as described above is received between two different wavelengths λ1 and λ2.

  In the transmission line fiber 210 in which the optical pulse of the adjacent wavelength is transmitted, when there is no attenuation of the optical power, the amount of red chirp and blue chirp received by the optical pulse of λ2 is equal to λ2 The chirps generated while the light pulses of λ1 are overtaken and overtaken by the light pulses of λ1 cancel each other, and the light pulses of λ2 are not subjected to a phase shift due to the cross-phase modulation effect.

  However, as shown in FIG. 43 (b), the optical signal attenuates as the optical signal propagates through the transmission line fiber 210. Therefore, as shown in FIG. The amount of red chirp that catches up with and overlaps the light pulse of λ2 is slightly less than the amount of blue chirp that occurs while the light pulse of λ1 overlaps the light pulse of λ2 and the light pulse of λ1 overtakes the light pulse of λ2. Therefore, the amount of chirp between the two does not cancel each other, and the red chirp generated at a point where the optical signal power is high remains slightly.

In this way, during the transmission of the section of the transmission line fiber 210, as shown in FIG. 43 (d), the red chirp always remains due to the influence of the cross-phase modulation, and only ΔC remains as a whole. It becomes. In this case, the optical pulse of λ2 undergoes a phase shift due to the remaining red chirp, and the group velocity propagating through the optical fiber changes.
Also, normally, in the relay device that constitutes the lumped amplifier 220, dispersion compensation is performed to suppress waveform deterioration. By this dispersion compensation function, the propagation delay time difference of the optical signals of the adjacent wavelengths λ1 and λ2 at each relay stage is compensated, and the bit arrangement of the adjacent wavelength signals input to the lumped amplifier 220 at each stage is substantially the same. In this case, since the residual red chirp described above is accumulated in each relay stage, the residual chirp amount ΔC in the unit relay section is relayed as shown in FIGS. 43 (c) and 43 (d). The number of stages is multiplied, which leads to a large waveform deterioration.

  Therefore, the optical pulse of λ2 undergoes a phase shift due to the remaining red chirp, the group velocity that propagates through the optical fiber changes, and this influence further remains at each relay interval. In the case of a phase-modulated optical signal, it becomes a direct noise component of the data symbol and degrades the transmission performance.

In this way, mutual phase modulation causes phase fluctuations due to intensity distortion between adjacent wavelengths and degrades transmission characteristics. Therefore, it is extremely difficult for wavelength-division long-distance optical transmission systems in which optical pulses collide between adjacent wavelengths. It becomes a problem.
In addition, there exists a thing described in the following nonpatent literature 1 as a technique relevant to this invention.

G.Charlet et.al., “Nonlinear Interactions Between 10Gb / s NRZ Channels and 40Gb / s Channels with RZ-DQPSK or PSBT Format, over Low-Dispersion Fiber”, Mo3.2.6, ECOC2006

  It has been studied to mix and transmit a channel of a phase-modulated optical signal modulated by the phase modulation method as described above together with a channel of an intensity-modulated optical signal. That is, the frequency utilization efficiency can be increased by mixing the intensity-modulated optical signal and the phase-modulated optical signal, or stepwise and efficiently while using the existing equipment for wavelength multiplexing transmission using the intensity-modulated optical signal. In addition, the transmission system can be upgraded.

However, when it is necessary to transmit the intensity-modulated optical signal and the phase-modulated optical signal together as described above when upgrading the transmission system, the nonlinear effect (XPM) caused by the intensity change of the intensity-modulated optical signal is required. The influence greatly affects the reception quality of the phase-modulated optical signal.
That is, in a system premised on wavelength division multiplexing transmission of an intensity-modulated optical signal, a chromatic dispersion per unit length is relatively small, for example, a dispersion-shifted fiber (NZDSF) is applied as a transmission line fiber. By doing so, it may be possible to obtain the optimum received signal quality by balancing the effects of SPM, XPM, etc. as described above.

  However, assuming that a function for multiplexing a phase-modulated optical signal such as a DQPSK modulated signal is added to a transmission system having such a transmission line fiber having a small chromatic dispersion per unit length, the NZDSF is capable of phase modulation. It cannot be said that the code walk-off between wavelength channels (or the relative propagation speed difference in the transmission path) is so large that the influence of XPM on the optical signal can be avoided.

In other words, if NZDSF is used, phase modulated optical signals are arranged in a channel arrangement that can be used for wavelength multiplexing of conventional intensity modulated optical signals, and mixed with intensity modulated optical signals of other channels. The degradation of the received signal quality of the phase-modulated optical signal due to XPM is greater than in the case of signal-only WDM transmission.
Also in Non-Patent Document 1, when transmitting an NZDSF which is a fiber having a small chromatic dispersion value by mixing an intensity modulated optical signal of 10 Gbps and a phase modulated optical signal of 43 Gbps, adjacent wavelengths of the phase modulated optical signal of 43 Gbps are transmitted. When a 10 Gb / s intensity modulated optical signal is placed in the channel, the received signal quality is degraded as compared with the case where a 43 Gbps phase modulated optical signal is placed in all wavelength channels. In Non-Patent Document 1, even when the polarization state is the optimum (orthogonal) state, the Q value indicating the received signal quality is deteriorated compared to the WDM transmission of only the 43 Gbps phase-modulated optical signal, and the polarization is parallel. In the state, the Q value is deteriorated by about 3 dB.

That is, when the transmission system is upgraded, when the intensity modulated optical signal and the phase modulated optical signal are mixed and transmitted as described above, the conventional WDM transmission of only the 10 Gbps intensity modulated optical signal or the phase modulated optical signal is performed. Compared to the case of WDM transmission, it is necessary to take more aggressive measures to suppress the influence of XPM.
Non-Patent Document 1 does not provide means for suppressing the influence of XPM on a phase-modulated optical signal when such intensity-modulated optical signal and phase-modulated optical signal are mixed and transmitted.

Accordingly, one of the objects of the present invention is to suppress transmission quality deterioration in a network system in which intensity-modulated optical signals and phase-modulated optical signals are mixed.
In addition, the present invention is not limited to the above-described object, and other effects of the present invention can be achieved by the respective configurations shown in the best mode for carrying out the invention described below, and cannot be obtained by conventional techniques. It can be positioned as one of

For this reason, the present invention is characterized by the following optical transmission apparatus.
That is, the optical transmission device of the present invention is an optical transmission device that relays and transmits a wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line. A demultiplexer that separates the demultiplexed wavelength multiplexed signal into a second demultiplexed wavelength multiplexed signal, a detour sending unit that sends the first demultiplexed wavelength multiplexed signal separated by the demultiplexer to a detour, and the detour A wavelength division multiplexing repeater that wavelength-multiplexes and relays the second demultiplexed wavelength multiplexed signal from the demultiplexing unit, and the demultiplexing unit, At least one of the detour sending unit and the wavelength division multiplexing relay unit selectively transmits one of the intensity-modulated optical signal and the phase-modulated optical signal from the first separated wavelength multiplexed signal. It has a function to prevent and Among the separating unit and the wavelength multiplexing relay unit, at least one, from the second separation wavelength multiplexed signal, selectively blocks the other one of the transmission of the intensity modulation optical signal and the phase modulation optical signal It is characterized by having functions.

The optical transmission apparatus related to the present invention is an optical transmission apparatus that repeats and transmits wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line, and the input wavelength-multiplexed signal light Information for collecting network management information related to characteristics of a transmission path constituting a network to which the optical transmission apparatus is applied and a modulation scheme of a transmission optical signal; A collecting unit and a control unit for controlling a route switching setting by the route switching unit based on the management information collected by the information collecting unit are provided.

Further, the optical transmission apparatus related to the present invention is an optical transmission apparatus that relays transmission through transmission path wavelength multiplexed signal light of an intensity modulation optical signal and phase modulation optical signals, one of said wavelength-multiplexed signal input A separation unit that separates an optical signal in a certain wavelength band from an optical signal in another wavelength band, a wavelength assignment changing unit that changes a wavelength assignment for the optical signal in the partial wavelength band separated by the separation unit, A wavelength division multiplexing repeater that multiplexes and repeats an optical signal whose wavelength assignment has been changed by the wavelength assignment modulation unit and an optical signal in the other wavelength band is provided.

Furthermore , an optical transmission apparatus related to the present invention is an optical transmission apparatus that repeats and transmits a wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line, and The wavelength allocation conversion unit performs wavelength allocation conversion so that the wavelength modulation optical signal and the phase modulation optical signal are alternately wavelength-allocated, and outputs the wavelength-multiplexed optical signal, and the wavelength allocation conversion unit performs wavelength allocation conversion. For the wavelength multiplexed optical signal that has been converted, an interleaver demultiplexing unit that divides wavelength pairs every other wavelength into two sets of wavelength groups, and two wavelength groups that are divided by the interleaver demultiplexing unit On the other hand, a bit time difference giving unit that gives a relatively different bit time difference, and an interleaver combination that combines and outputs the optical signals of the two wavelength groups from the bit time difference giving unit. And parts, that includes a are characterized.
Further, the optical transmission apparatus related to the present invention is an optical transmission apparatus that relays transmission through transmission path wavelength multiplexed signal light of an intensity modulation optical signal and phase modulation optical signals, the in the wavelength-multiplexed signal input A separation unit that separates the intensity-modulated optical signal and the phase-modulated optical signal; an intensity-difference imparting unit that imparts an intensity difference to the phase-modulated optical signal and the intensity-modulated optical signal separated by the separation unit; And a wavelength division multiplexing relay unit that wavelength-multiplexes and relays the intensity-modulated optical signal and the phase-modulated optical signal to which the intensity difference is imparted by the difference imparting unit.

  As described above, according to the present invention, it is possible to suppress deterioration in transmission quality in a network system in which intensity modulated optical signals and phase modulated optical signals are mixed. In addition, because the transmission system can be upgraded with phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected to increase, and network design and management flexibility can be increased. Can do.

1 is a diagram illustrating a network system to which an optical transmission apparatus according to a first embodiment of the present invention is applied. It is a block diagram explaining the structure of the optical transmission apparatus in 1st Embodiment with the structural example of a data transfer network. It is a figure for demonstrating the specific structural example of a delay block part. It is a figure for demonstrating the specific structural example of a delay block part. It is a figure which shows the classification example of the management information of the network system which an information collection part collects. (A), (b) is a figure for demonstrating that the influence of the mutual phase modulation in a signal receiving end can be suppressed by providing a propagation delay time difference between an intensity modulated optical signal and a phase modulated optical signal. is there. It is a figure for demonstrating that the influence of the mutual phase modulation in a signal receiving end can be suppressed by providing a propagation delay time difference between an intensity modulation optical signal and a phase modulation optical signal. It is a figure for demonstrating that the influence of the mutual phase modulation in a signal receiving end can be suppressed by providing a propagation delay time difference between an intensity modulation optical signal and a phase modulation optical signal. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure which shows the modification of 1st Embodiment of this invention. It is a figure for demonstrating the effect by the 1st Embodiment and the 1st-3rd modification derived from 1st Embodiment. It is a figure for demonstrating the effect by the 1st Embodiment and the 1st-3rd modification derived from 1st Embodiment. It is a block diagram which shows the optical transmission apparatus concerning 2nd Embodiment of this invention. It is a figure for demonstrating the effect in 2nd Embodiment of this invention. It is a figure for demonstrating the effect in 2nd Embodiment of this invention. It is a figure for demonstrating the effect in 2nd Embodiment of this invention. It is a figure for demonstrating the effect in 2nd Embodiment of this invention. It is a block diagram which shows the optical transmission apparatus (optical transmission apparatus) concerning 3rd Embodiment of this invention. It is a block diagram which shows the other optical transmitter in 3rd Embodiment. It is a block diagram which shows the other optical transmitter in 3rd Embodiment. (A)-(e) is a figure for demonstrating that the influence of the mutual phase modulation in a signal receiving end can be suppressed by giving chromatic dispersion to an intensity modulation optical signal. (A)-(e) is a figure for demonstrating that the influence of the mutual phase modulation in a signal receiving end can be suppressed by giving chromatic dispersion to an intensity modulation optical signal. It is a figure for demonstrating the effect in 3rd Embodiment of this invention. It is a figure for demonstrating the effect in 3rd Embodiment of this invention. It is a figure which shows the structure of the data transfer network with which the optical transmission apparatus concerning 4th Embodiment of this invention is applied. It is a block diagram which shows the optical transmission apparatus concerning 4th Embodiment of this invention. It is a figure which shows the structure of the data transfer network with which the optical transmission apparatus concerning 5th Embodiment of this invention is applied. It is a block diagram which shows the optical transmission apparatus concerning 5th Embodiment of this invention. It is a figure which shows the structure of the data transfer network with which the optical transmission apparatus concerning 6th Embodiment of this invention is applied. It is a block diagram which shows the optical transmission apparatus concerning 6th Embodiment of this invention. It is a figure which shows the structure of the data transfer network with which the optical transmission apparatus concerning 7th Embodiment of this invention is applied. It is a block diagram which shows the optical transmission apparatus concerning 7th Embodiment of this invention. It is a block diagram which shows the optical transmission apparatus concerning 8th Embodiment of this invention. It is a block diagram which shows the optical transmission apparatus concerning 9th Embodiment of this invention. (A)-(c) is a conceptual diagram which shows the phenomenon of the mutual phase modulation by an optical pulse. (A)-(d) is a figure for demonstrating the principle which residual chirp produces by the influence of the mutual phase modulation which arises in a relay area.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the present invention is not limited to the following embodiments. In addition to the above-described object of the present invention, other technical problems, means for solving the technical problems, and operational effects will become apparent from the disclosure of the following embodiments.
[A] Description of First Embodiment FIG. 1 is a diagram showing a network system to which an optical transmission apparatus according to a first embodiment of the present invention is applied. A network system 100 shown in FIG. 1 includes a data transfer network 110, a control network 120 that controls the data transfer network 110, and a management plane 130 that manages the control network 120. The data transfer network 110 is formed by connecting a plurality of optical transmission devices 111 to each other. In addition, the control network 120 is configured by connecting a plurality of control nodes 121 provided corresponding to the optical transmission apparatus 111 constituting the data transfer network 110.

  As a result, the control node 121 constituting the control network 120 extracts information held by the optical transmission device (relay device) 111 to be controlled in the data transfer network 110, while the optical transmission device 111 to be controlled (each of FIG. 1). The operation setting in the dotted line reference) can be controlled. In the management plane 130, the information extracted by each control node 121 is sucked up by a management protocol such as SNMP (Simple Network Management Protocol).

  FIG. 2 is a block diagram illustrating the configuration of the optical transmission apparatus 111 together with a configuration example of the data transfer network 110. In the data transfer network 110 shown in FIG. 2, the optical transmission apparatuses 111-1 to 111-5 are connected in a ring shape through a transmission line fiber (for example, NZDSF) 140 having a small dispersion value, and the optical transmission apparatus 111-4. ˜111-8 are also connected in a ring shape through a transmission line fiber (for example, NZDSF) 140 having a relatively small dispersion value. In FIG. 2, the optical transmission devices 111-1 to 111-8 are simply referred to as the optical transmission device 111 when they are not distinguished.

  Here, the optical transmission apparatuses 111-1 to 111-8 constituting the data transfer network 110 shown in FIG. 2 have functions such as path switching in units of wavelengths (channels) for input wavelength multiplexed signals. In addition, an intensity-modulated optical signal and a phase-modulated optical signal are mixed as wavelength-multiplexed optical signals (that is, an intensity-modulated optical signal and a phase-modulated optical signal are mixed in a wavelength-multiplexed channel. When an optical signal is input, it is possible to perform signal processing that can suppress waveform deterioration at the receiving end due to the influence of XPM received by the phase-modulated optical signal from the intensity-modulated optical signal.

  Specifically, the optical transmission apparatus 111 includes an OXC 4 as shown in FIG. 2 and also includes a wavelength multiplexed optical signal (a mixed signal of a phase-modulated optical signal and an intensity-modulated optical signal) input before or after the OXC 4. The delay block unit 1 for providing a delay difference between the phase modulated optical signal (denoted as phase modulated signal in the figure) and the intensity modulated optical signal (denoted as intensity modulated signal in the figure), and an information collecting unit 2 and the control unit 3 can be provided. Furthermore, a dispersion compensator for compensating for the dispersion of the transmission line fiber can be provided in the preceding stage of the delay block unit 1, and a concentrated amplifier can be provided at the transmission end of the optical signal to the downstream transmission line fiber.

  The delay block unit 1 demultiplexes the intensity modulated optical signal and the phase modulated optical signal in the input mixed signal, and the intensity modulated optical signal and the phase modulated optical signal demultiplexed by the demultiplexing unit 11. A delay unit 12 for providing a delay difference and a multiplexing unit 13 for combining the intensity-modulated optical signal and the phase-modulated optical signal to which the delay difference has been given by the delay unit 12. Since the delay unit 12 only needs to give a delay time difference between the intensity-modulated optical signal and the phase-modulated optical signal, the delay is given to the phase-modulated optical signal in FIG. It is good also as giving a delay of a different time to both. Further, in the above description and FIG. 2, it is described that the intensity-modulated optical signal and the phase-modulated optical signal are separated by the demultiplexing unit 11, but the implementation of the selection function of the intensity-modulated optical signal and the phase-modulated optical signal is branched. It is not restricted to the part 11. For example, the demultiplexing unit 11 is a simple optical branch having no wavelength selectivity, and the multiplexing unit 13 has a wavelength-selective switch function and selectively selects an intensity-modulated optical signal and a phase-modulated optical signal from two input terminals. The delay unit 12 may be provided with a wavelength selective blocking function.

3 and 4 are diagrams for explaining a specific configuration example of the delay block unit 1. For example, as shown in FIG. 3, the delay block unit 1 includes an optical circulator 14, a wavelength selective switch 15, a delay device 16, and a reflector 17.
Regarding the mixed signal input to the wavelength selective switch 15 through the optical circulator 14, the light having the wavelength of the intensity-modulated optical signal is output to the port without the delay device 16 through reflection by the reflector 15 a in the wavelength selective switch 15. After that, the light is reflected by the reflector 17 and returned to the input port of the wavelength selective switch 15. On the other hand, the light having the wavelength of the phase-modulated optical signal is output to the port having the delay device 16 by the wavelength selective switch 15 and then reflected by the reflector 17 to return to the input port of the wavelength switch 15. . Accordingly, it is possible to give a delay time difference between the intensity modulated optical signal and the phase modulated optical signal. The wavelength selective switch 15 described above functions as the demultiplexing unit 11 and the multiplexing unit 13 illustrated in FIG. 2, and the delay unit 16 functions as the delay unit 12 illustrated in FIG.

Alternatively, for example, as shown in FIG. 4, the delay block unit 1 includes an optical circulator 14, a delay unit 16, and a reflector 17 similar to those in FIG. 3, and a wavelength selection that performs a path switching operation different from that in FIG. 3. A switch 15 'can also be provided.
Regarding the mixed signal input to the wavelength selective switch 15 ′ through the optical circulator 14, the light having the wavelength of the intensity-modulated optical signal is reflected by the reflector 15 a in the wavelength selective switch 15 ′ and reflected by an external reflector. The process returns to the input port of the wavelength selective switch 15 'without passing through. On the other hand, the light having the wavelength of the phase-modulated optical signal is output to a certain port of the delay device 16 and then reflected by the reflector 17 to return to the input port of the wavelength selective switch 15 ′. Also in the delay block unit 1 configured in this way, a delay difference can be given between the intensity modulated optical signal and the phase modulated optical signal.

  Therefore, at least two optical signals having relatively different bit time differences from the input wavelength multiplexed optical signal by the wavelength selective switches 15 and 15 'forming the demultiplexing unit 11 and the delay unit 16 as the delay unit 12. The bit time difference giving signal generating unit for generating Further, the demultiplexing unit 11 has a function as a demultiplexing unit that separates an input wavelength multiplexed optical signal into a phase modulation optical signal and an intensity modulation optical signal, and the delay unit 12 is separated by the demultiplexing unit 11. In addition, a bit time difference providing unit for applying a different bit time difference to each optical signal is configured.

Then, as described later, the delay block unit 1 gives a delay time difference between the intensity-modulated optical signal and the phase-modulated optical signal as described above, thereby affecting the influence of the XPM that the phase-modulated optical signal receives from the intensity-modulated optical signal. Waveform deterioration at the receiving end can be suppressed.
In the wavelength selective switches 15 and 15 'shown in FIGS. 3 and 4, the multiplexer / demultiplexer 15b is provided at the input port to which the optical signal from the optical circulator 14 is input, and the wavelength from the optical circulator 14 is increased. The multiplexed optical signal is demultiplexed and incident on the reflectors 15a associated with the respective wavelengths, while the optical signals incident on the input ports leading from the respective reflectors 15a to the optical circulator 14 are multiplexed. ing. In addition, each reflector 15a is configured so that the angle of the reflecting surface is set to be rotatable under the control of the control unit 3, and an input port provided with the above-described multiplexer / demultiplexer 15b and another port. These optical coupling relationships can be switched as appropriate.

As a result, at least two optical signals from the bit time difference adding signal generating unit are input by the wavelength selective switches 15 and 15 ′ forming the multiplexing unit 13, and between the phase-modulated optical signal and the intensity-modulated optical signal. A wavelength-multiplexed optical signal output unit configured to generate and output a wavelength-multiplexed optical signal to which a bit time difference is given is configured.
Further, the information collecting unit 2 collects management information about the network system 100 through exchange of control signals with the control node 121 (see FIG. 1). Further, the control unit 3 controls the operation of the optical transmission apparatus 111 based on the management information collected by the information collection unit 2. Specifically, based on the management information collected by the information collecting unit 2, it is determined whether the phase-modulated optical signal is susceptible to XPM in the transmission line fiber 140, and the phase-modulated optical signal is determined. Is controlled to be affected by XPM, the wavelength selective switch (reference numeral 15 in FIG. 3 or reference numeral 15 ′ in FIG. 4) of the delay block unit 1 is controlled to control the phase-modulated optical signal as described above and Control is performed so as to give a delay difference between the intensity-modulated optical signals.

  FIG. 5 shows an example of management information types of the network system 100 collected by the information collection unit 2. As shown in FIG. 5, in the information collecting unit 2, the type (type # 1) of the transmission line fiber 140, the dispersion amount of the dispersion compensation module (type # 2), the span loss (type # 3) of the transmission line fiber 140, Distance of transmission line fiber 140 (type # 4), optical signal modulation method (type # 5) of each channel, bit rate (or symbol rate, type # 6) of each signal, and usage status of signal light wavelength ( Information on type # 7) is collected.

  The management information of types # 1, # 2, and # 4 to # 7 can be extracted from setting control information exchanged with the control network 120, and management information (span loss) of type # 3. , The input power (A) of the signal light to the optical transmission device 111 is monitored, and the signal light, which is included in the OSC (Optical Supervisory Channel) light and whose input power is monitored, is transmitted to the upstream side optical transmission device 111. The output power (B) at the time of transmission is acquired, and if a Raman amplifier (not shown) is provided, the information (C) of the Raman gain of the transmission line fiber is acquired and calculated (span loss = B−A). -C).

  For example, in the optical transmission device 111-3 shown in FIG. 2, the input power (A) of the optical signal from the optical transmission device 111-2 is monitored and the optical signal in the optical transmission device 111-2 is transmitted through the OSC light. The output power information (A) is acquired, the Raman gain in the transmission line fiber 140 between the optical transmission apparatuses 111-2 and 111-3 is acquired (C), and the span loss (= B−A−C) is acquired from these information. ) Is derived.

  The information of types # 5 to # 7 described above can also be extracted from information of an optical spectrum monitor that monitors the optical spectrum in the signal light wavelength band. Further, the information on the fiber type, which is the information of type # 1, can be estimated from the obtained information of types # 2 to # 4. That is, even when the fiber type is unknown, the transmission line fiber to be applied can be estimated from the dispersion amount of the dispersion compensation module, the span loss of the transmission line fiber, and the distance of the transmission line fiber.

  In the control unit 3 described above, for example, based on the management information of the type # 1, the transmission line fiber 140 as the signal transmission destination is a fiber having a relatively large dispersion value such as SMF (Single Mode Fiber). Since the walk-off between the intensity-modulated optical signal and the phase-modulated optical signal is large, it is determined that the influence of the XPM that the phase-modulated optical signal receives in the transmission line fiber 140 is relatively small (not easily affected) When the transmission line fiber 140 of the transmission destination is a fiber having a relatively small dispersion value such as NZDSF, the influence of the XPM that the phase modulation optical signal receives in the transmission line fiber 140 is relatively large (easy to be affected). Judgment can be made.

  When the control unit 3 determines that the influence of XPM is relatively large as described above, the delay block is configured so that a delay time difference is provided between the phase-modulated optical signal and the intensity-modulated optical signal as described above. Control part 1. In this case, by controlling the selection path in the wavelength selective switches 15 and 15 ′ (see FIGS. 2 to 4) as the multiplexing unit 13, the multiplexing unit 13 delays the phase-modulated optical signal. 12 and an optical signal that does not pass through the delay unit 12 are output for the intensity-modulated optical signal. In other words, the control unit 3 controls the separation of the optical signals at the wavelength selective switches 15 and 15 ′ as the demultiplexing unit 11 based on the management information collected by the information collecting unit.

In addition, if the delay time in the delay unit 12 is configured to be variable, the control unit 3 uses the management information collected by the information collection unit 2 as a bit time difference giving signal generation unit. The amount of bit time difference provided by the delay unit 12 can be variably controlled.
In the optical transmission device 111 configured as described above, the control unit 3 is easily affected by XPM in the transmission line fiber 140 based on the management information collected by the information collection unit 2 (the transmission line fiber 140 Recognizing that the chromatic dispersion value is small, etc.), the delay block unit 1 is controlled to change the route between the intensity-modulated optical signal and the phase-modulated optical signal in the relay device, thereby delaying both optical signals. Giving time difference.

  By providing such a delay time difference at the optical transmission device 111 at each relay stage, the bit arrangement between signals at the output of each optical transmission device 111 does not overlap, so that the cumulative amount of phase modulation by XPM decreases. The waveform deterioration of the phase-modulated optical signal can be suppressed. Here, both the intensity-modulated optical signal and the phase-modulated optical signal are not limited to one signal, and the route may be switched for a plurality of signals at once. In the figure, the delay unit 12 is provided in the route followed by the phase-modulated optical signal. However, the route of the intensity-modulated optical signal and the phase-modulated optical signal is switched, and the delay unit is provided in the route followed by the intensity-modulated optical signal. It is good. In addition, it is effective that the delay unit 12 is provided in a relay node that is downstream of a transmission section including a fiber that is greatly affected by XPM and first includes a chromatic dispersion compensation module. Furthermore, it may be desirable that the delay amount of the delay unit of each optical transmission device 111 is random. As a result of the relative bit arrangement relationship between the intensity-modulated optical signal and the phase-modulated optical signal in the wavelength-multiplexed optical signal transmitted in the optical transmission device 111 at each relay stage becomes irregular, dispersion for each relay section This is because even if the remaining amount of compensation is regular, it is possible to suppress the risk that the red chirp accumulation increases in a simple additive manner.

  6 (a), 6 (b), 7 and 8 show the effect of cross-phase modulation at the signal receiving end by providing a propagation delay time difference between the intensity modulated optical signal and the phase modulated optical signal. It is a figure for demonstrating that can be suppressed. For example, assuming two cases by simplifying the bit arrangement model of the phase-modulated optical signal converted into the RZ signal and the intensity-modulated optical signal, the intensity in one transmission section (one span) between the optical transmission apparatuses 111 is assumed. When the propagation speed of the phase-modulated optical signal is high by the amount of 4 bits of the modulated optical signal, the bit waveform of the intensity-modulated optical signal of the phase-modulated optical signal as shown in FIGS. 6 (a) and 6 (b) A mode of overtaking at the level can be assumed.

  That is, in the case of FIG. 6A, the phase-modulated optical signal overtakes the rising and falling of the intensity-modulated optical signal one by one on the upstream side of the transmission line fiber 140 even during one span (red chirp and blue). (Chirping), overtaking the rise of the intensity-modulated optical signal in the middle stream (occurring red chirp), and at the input point to the next relay stage, the falling edge of the bit of the intensity-modulated optical signal 4 bits ahead at the time of transmission The falling edge of the phase-modulated optical signal is aligned (occurrence of blue chirp).

  On the other hand, when the intensity-modulated optical signal is delayed by 4 bit times from the phase-modulated optical signal, the overtaking mode at the bit waveform level is, for example, 4 bits as shown in FIG. It differs from the case of FIG. 6A according to the 4-bit pattern ahead. In this case, on the upstream side of the transmission line fiber 140, the phase-modulated optical signal overtakes the fall of the intensity-modulated optical signal, and at the midstream portion, the rise and rise of the intensity-modulated optical signal that is 2 bits ahead at the time of transmission. Overtaking the downstream (occurrence of red chirp and blue chirp), at the input point to the next relay stage, the rising edge of the bit of the intensity modulated optical signal 4 bits ahead and the rising edge of the bit of the phase modulated optical signal at the transmission time point They are ready (red chirping).

  Here, if a dispersion compensation function (not shown) is provided in the preceding stage of the delay block unit 1 in the optical transmission apparatus 111 and the centralized amplifier 30 is provided in a position before sending to the transmission line, the transmission line fiber 140 is interposed. When the optical transmission apparatus 111 does not provide a delay time difference between the phase-modulated optical signal and the intensity-modulated optical signal, and the dispersion of the transmission line fiber 140 is compensated to “0” by the dispersion compensation function described above, The relative bit arrangement relationship between the intensity-modulated optical signal and the phase-modulated optical signal at the time of input to the centralized amplifier 30 is always the same (for example, always FIG. 6A). In this case, as shown in FIG. 7, since the remaining chirp in each relay section is accumulated, the signal receiving end is affected by XPM.

  On the other hand, when a delay time difference is provided between the phase-modulated optical signal and the intensity-modulated optical signal in the optical transmission device 111 interposed in the transmission line fiber 140, it is input to the delay block unit 1 by the above-described dispersion compensation function. Even if the chromatic dispersion is compensated to “0” at the time when the signal is input, the relative bit arrangement of the intensity-modulated optical signal and the phase-modulated optical signal at the time of input to the centralized amplifier 30 provided on the output side of the OXC 4 The relationship differs at each relay stage, for example, as shown in FIG. 6 (a) and FIG. 6 (b). In this case, as shown in FIG. 8, the residual chirp in each relay section is canceled as a whole. Therefore, the influence of XPM at the signal receiving end, particularly phase modulation, is more than that shown in FIG. The influence which an optical signal receives can be suppressed.

  As described above, according to the first embodiment of the present invention, the delay unit 12 and the multiplexing unit 13 constituting the delay block unit 1 can suppress the influence of XPM at the signal receiving end. There is an advantage that deterioration of transmission quality can be suppressed in a network system in which signals and phase-modulated optical signals are mixed. In addition, because it is possible to easily upgrade a transmission system using phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected, and network management flexibility can be increased. it can.

[A1] Description of First Modification of First Embodiment In the optical transmission device 111 of the first embodiment described above, a delay block unit is provided to provide a bit delay time between the intensity-modulated optical signal and the phase-modulated optical signal. However, according to the present invention, for example, as shown in FIGS. 9 to 12, the function as a delay block unit 1 is added to the function as a branch insertion unit for branching / inserting an optical signal for each wavelength. Can be incorporated.

  For example, as shown in FIG. 9, an optical coupler (branching unit) 21 that branches an input wavelength-multiplexed optical signal (mixed signal of an intensity-modulated optical signal and a phase-modulated optical signal) into two and an optical coupler 21 are branched. A delay unit (bit time difference providing unit) 22 for giving a delay difference (bit time difference) to the wavelength multiplexed optical signal (intensity modulated optical signal and phase modulated optical signal) of the other path, and N (N is a plurality) And a wavelength selective switch 23 having an input / through function of one output at the input.

  That is, the wavelength multiplexed optical signal delayed by the delay unit 22 is input through one of the N-1 add ports (or the first through port TP1 for the delayed wavelength multiplexed optical signal), while being branched. The other wavelength-division multiplexed optical signal branched at the minute 21 and not delayed by the delay device 22 is input through the through port (second through port TP2) and input from the through ports TP1 and TP2 and each add port. With respect to the optical signal, an optical signal to be output from the output port is selected for each wavelength and output as a wavelength-multiplexed optical signal (mixed signal output).

  That is, when a wavelength-division multiplexed optical signal whose modulation method is defined in units of wavelengths is input as a mixed signal, the wavelength selective switch 23 controls the wavelength selective switch 23 in the control unit 3 so that the wavelength of the intensity modulated optical signal is controlled. As for the signal, the optical signal from the through port is output to the output port, while the wavelength signal of the phase modulated optical signal is operated to output the optical signal delayed by the delay unit 22 from the add port to the output port. it can. In this case, the phase modulation optical signal from the through port and the intensity modulation optical signal from the add port are blocked (blocked) from being output to the output port.

  By doing so, the output mixed signal is output with a delay difference added to the phase-modulated optical signal. Accordingly, the wavelength selective switch 23 constitutes a wavelength multiplexed optical signal output unit that outputs a wavelength multiplexed optical signal including the optical signal to which the bit time difference is given by the delay unit 22. In FIG. 9, the phase modulated optical signal is delayed, but the intensity modulated optical signal may be delayed.

  10 includes an optical coupler 21b that further splits one of the lights branched by the optical coupler 21a into two, and one branched by the optical coupler 21b is sent to the delay device 22, and the other is a plurality of drop ports. 9 is different from the one shown in FIG. The wavelength selective switch 21 can select and output an optical signal to be output to a plurality of drop ports for the wavelength multiplexed optical signal from the optical coupler 21b.

  Further, in the one shown in FIG. 11, the functions as the optical couplers 21a and 21b and the wavelength selective switch 21c shown in FIG. 10 are realized by a single wavelength selective switch 21d having one input and three or more output ports. It is. The wavelength selective switch 21 d outputs the mixed signal of the wavelength component as it is from the output port connected to the through port of the wavelength selective switch 23 and also from the output port connected to the delay device 22 for the input mixed signal. The remaining output port of the wavelength selective switch 21d can be used as a drop port.

In addition, in the one shown in FIG. 12, a wavelength selective switch that receives one mixed signal branched by the optical coupler 21a and guides one of the output ports to the delay device 22, while applying the other output port as a drop port. 9 is different from that shown in FIG. 9 in that 21e is interposed.
9 to 12, the same reference numerals have substantially the same function. In the optical transmission apparatus configured as shown in FIG. 9 to FIG. 12, the phase-modulated optical signal and the intensity-modulated optical signal are combined with the OADM function for performing branching or insertion for each wavelength by the wavelength selective switches 21c to 21e and 23. In addition, a function as a delay block unit for providing the same bit delay time difference as in the first embodiment can be provided.

  In the case of FIG. 9, the optical coupler 21 and the delay device 22 cooperate to form a bit time difference giving signal unit, and the wavelength selective switch 23 forms a wavelength multiplexed signal output unit. In the case of the configuration of FIG. 10, the optical couplers 21a and 21b and the delay device 22 constitute a bit time difference giving signal generation unit, and the wavelength selective switch 23 constitutes a wavelength multiplexed signal output unit.

  Similarly, in the configuration of FIG. 11, the wavelength selective switch 21 d and the delay device 22 cooperate to configure a bit time difference giving signal generation unit, and the wavelength selective switch 23 functions as a wavelength multiplexed signal output unit. In the case of the configuration of FIG. 12, the optical coupler 21a, the wavelength selective switch 21e, and the delay device 22 cooperate to form a bit time difference giving signal generation unit, and the wavelength selective switch 23 serves as a wavelength multiplexed signal output unit. Configure.

[A2] Description of Second Modification of First Embodiment In the optical transmission apparatus according to the first modification described above, the delay block unit 1 functions as a branching / inserting unit that branches / inserts an optical signal for each wavelength. However, according to the present invention, for example, as shown in FIGS. 13 to 15, the function as the delay block unit 1 can be incorporated into the function as the OXC unit.

  In the optical transmission apparatus shown in FIG. 13, the same information collection unit 2 and control unit 3 as those in the first embodiment are provided, and the same components (reference numeral 21d) as those in the optical transmission apparatus shown in FIG. , 22, 23), wavelength selective switches 24-1, 24-2, delay units (bit time difference providing units) 25-1, 25-2, and wavelength selective switches (wavelength multiplexed optical signal output units) 26-1, 26. -2 are provided in parallel corresponding to the number of input / output port pairs (2).

  As a result, the wavelength selective switch 24-1 introduces the mixed signal from the first input port (Port1-IN), and the wavelength selective switch 26-1 outputs the mixed signal through the first output port (Port1-OUT). . The wavelength selective switch 24-2 introduces a mixed signal from the second input port (Port2-IN), and the wavelength selective switch 26-2 outputs a mixed signal through the second output port (Port2-OUT).

  In addition, in the wavelength selective switches 24-1 and 24-2 on the input side, at least one of the drop ports is connected to an add port of the wavelength selective switches 26-2 and 26-1 corresponding to the other output port. As a result, the path of the optical signal from the first input port (Port1-IN) is switched for each wavelength and output from the second output port (Port2-OUT) or from the second input port (Port2-IN). OXC is realized by switching the path of the optical signal for each wavelength and outputting from the first output port (Port1-OUT). In FIG. 13, attention is paid to the connection between the drop port of the wavelength selective switch 24-2 and the add port of the wavelength selective switch 26-1.

  Here, in the optical transmission apparatus shown in FIG. 13, the bit delay time difference between the intensity-modulated optical signal and the phase-modulated optical signal is the same as that in the above-described first embodiment even for the mixed signal whose path is switched. The structure which provides is provided. For example, a delay device 27-2 and an optical coupler 28-2 are provided between the drop port of the wavelength selective switch 24-2 and the add port of the wavelength selective switch 26-1. Although not shown, a similar configuration can be provided between the drop port of the wavelength selective switch 24-1 and the add port of the wavelength selective switch 26-2.

  The delay device 27-2 gives a bit delay time similar to that of the delay device 22 in the first embodiment to the output signal from one drop port D1 in the wavelength selective switch 24-2, and the optical coupler 28- 2 multiplexes the output of the delay device 27-2 and the output of the other drop port D2 of the wavelength selective switch 24-2 (not connected to the delay device 27-2) to the wavelength selective switch 26-1. Output to add port.

The control unit 3 can set and control the path switching in each of the wavelength selective switches 24-1, 24-2, 26-1, and 26-2 based on the management information collected by the information collecting unit 2. .
In the optical transmission apparatus shown in FIG. 13 configured as described above, an operation when a signal input from the second input port (Port2-IN) is output to the first output port (Port1-OUT) will be described. The path of the mixed signal input from the second input port (Port2-IN) is switched by the wavelength selective switch 24-2, the phase-modulated optical signal is output to the port D1 where the delay device 27-2 is provided, and the intensity-modulated optical signal is The signal is output to the port D2 without the delay device 27-2. Then, after being multiplexed by the optical coupler 28-2, the output is input to the add port of the wavelength selective switch 26-1 led to the first output port (Port1-OUT), and then the output of the wavelength selective switch 26-1 To the first output port (Port1-OUT).

  The phase modulated optical signal forming the mixed signal output in this way is output with a delay difference added to the intensity modulated optical signal, regardless of whether the input source is the first or second input port. Can be. In the example shown in FIG. 13, the delay device 27-2 is inserted in the route of the phase-modulated optical signal, but the route of the intensity-modulated optical signal and the phase-modulated optical signal is switched to delay the route of the intensity-modulated optical signal. It is good also as inserting a vessel.

  FIG. 13 illustrates an OXC having two input ports and two output ports. However, according to the present invention, an OXC having two or more input / output ports may be used. In this case, the optical coupler 28-2 that branches the mixed signal to which the bit delay time is given is branched by the number of branches of (number of parallel input / output ports-1), and the branched mixed signal is output respectively. Connect to the add port of the wavelength selective switch led to the port. When the optical insertion loss of the optical coupler 28-2 increases as the number of branches increases, a wavelength multiplexing optical amplifier (not shown) is connected to the connection between the optical coupler 28-2 and the wavelength selective switch 26-1. It may be provided to compensate for the loss.

  Further, in the configuration shown in FIG. 14, as a configuration for providing a bit delay time difference for the mixed signal in which the route is switched, for example, an optical coupler 28a-2 and a delay device 27a- having functions different from those in the case of FIG. 2 is provided. Although not shown, a similar configuration can be provided between the drop port of the wavelength selective switch 24-1 and the add port of the wavelength selective switch 26-2.

  Here, the optical coupler 28a-2 branches the mixed signal from one drop port from the wavelength selective switch 24-2 into two, and one of the two branches is the delay device 27a-2. The same bit time delay as in the embodiment is given and input to the first add port A1, and the other of the two branches is input to the second add port without being delayed by the delay device 27a-2. . Even with this configuration, the OXC function is realized, and a delay difference with respect to the intensity modulated optical signal is added to the output phase modulated optical signal regardless of whether the input source is the first input port or the second input port. Can be output.

  15, optical couplers 24 a-1 to 24 c-1, 24 a-2-constituting the same constituent elements (reference numerals 21 a to 21 c, 22, 23) as those in the optical transmission apparatus shown in FIG. 24c-2, delay units 25-1, 25-2 and wavelength selective switches 26-1, 26-2 are provided in parallel corresponding to the number (2) of input / output port pairs. In the wavelength selective switches 24c-1 and 24c-2 on the input side, at least one of the drop ports is connected to an add port of the wavelength selective switches 26-2 and 26-1 that guide the other output port. As a result, the path of the optical signal from the first input port (Port1-IN) is switched for each wavelength and output from the second output port (Port2-OUT) or from the second input port (Port2-IN). OXC is realized by switching the path of the optical signal for each wavelength and outputting from the first output port (Port1-OUT).

  Here, in the optical transmission apparatus shown in FIG. 15, the same bit delay time difference is provided between the intensity-modulated optical signal and the phase-modulated optical signal for the mixed signal whose path is switched. It has a configuration. For example, an optical coupler 28a-2 and a delay device 27a-2 are provided between the drop port of the wavelength selective switch 24-2 and the add port of the wavelength selective switch 26-1. Although not shown, a similar configuration can be provided between the drop port of the wavelength selective switch 24-1 and the add port of the wavelength selective switch 26-2.

[A3] Description of Third Modification of First Embodiment In the optical transmission apparatus according to the first modification described above, wavelength selective switches 21c to 21e and 26 are appropriately used as shown in FIGS. Thus, the function as the delay block unit 1 is incorporated into the function as the branching / inserting unit for branching / inserting the optical signal for each wavelength, but instead of these wavelength selective switches 21c to 21e, 26, for example, As shown in FIGS. 16 and 17, a similar device can be configured by using a PLC (Planer Lightwave Circuit) type wavelength selective element such as AWG (Arrayed Waveguide Grating).

  16 includes an optical coupler 21 similar to that shown in FIG. 9 described above, and an AWG 31a and an optical switch (SW) as a configuration for guiding one optical signal branched by the optical coupler 21 to a drop port. ) 31 b, AWGs 32 a and 32 b and optical switches 32 c and 32 d are provided as a configuration for passing an optical signal through the other branched by the optical coupler 21 or inserting (adding) an optical signal from an add port, and a phase When outputting a mixed signal of a modulated optical signal and an intensity modulated optical signal, there is provided a delay device 33 that gives a relative bit delay difference to both.

  The AWG 31a receives a mixed signal (wavelength multiplexed optical signal) that is one of the branched lights from the optical coupler 21, demultiplexes the optical signal for each wavelength, and outputs it. The optical switch 31b is provided corresponding to each wavelength component demultiplexed by the AWG 31a, and switches the optical signal output by demultiplexing from the AWG 31a to a path leading to a drop port or an add port.

  Further, the delay unit 33 as the bit time difference adding unit is the same as the delay unit 22 in the first embodiment described above for the demultiplexed output optical signal from the AWG 31a input through the optical switch 31b (bit time difference). In the same manner as the optical switch 31b, it is provided corresponding to the optical signal of the wavelength output by the AWG 31a. The optical switch 32d selectively outputs one of the optical signal delayed by the delay device 33 and the optical signal having the corresponding wavelength on the add side.

  Further, the AWG 32a receives the mixed signal (wavelength multiplexed optical signal) which is the other branched light from the optical coupler 21, demultiplexes the optical signal for each wavelength, and outputs it. The optical switch 32c is provided corresponding to each wavelength component demultiplexed by the AWG 32a, and selects either one of the optical signal input from the optical switch 32d through the add port and the through-input optical signal from the AWG 32a. Selective output. Further, the AWG 32b combines the optical signals output from the optical switch 32c (wavelength multiplexing) and outputs them (mixed signal output).

  In FIG. 16, the optical switches 31 b and 32 d are illustrated with a focus on the configuration for switching for one wavelength, but the configuration for performing the switching for other wavelengths can be similarly provided. . Further, the control unit 3A controls switching at each of the optical switches 31b, 32c, and 32d based on the management information collected by the information collecting unit 2.

Therefore, the above-described optical coupler 21, AWG 31a, optical switch 31b, and delay device 33 generate a bit time difference giving signal that generates at least two optical signals having relatively different bit time differences from the input wavelength multiplexed optical signal. Parts.
In the optical transmission apparatus configured as described above, among the mixed signals input to the optical coupler 21, the intensity-modulated optical signal is output through through the switching in the optical switch 32c, but is output from the port. It is also possible to output through the drop port through switching at the switch 31b.

Therefore, the above-described AWGs 32a and 32b and the optical switches 32c and 32d cooperate to receive at least two optical signals from the above-described bit time difference providing signal generation unit, and to generate a phase-modulated optical signal and an intensity-modulated optical signal. A wavelength-multiplexed signal output unit for generating and outputting a wavelength-multiplexed optical signal to which a bit time difference is given is configured.
Among the mixed signals input to the optical coupler 21, for the phase-modulated optical signal, the signal that has passed through the delay device 33 is switched through the optical switch 31b and the switching through the optical switches 32d and 32c. Output from the AWG 32b. That is, after being demultiplexed by the AWG 31a on the drop side, the path is switched by the optical switch 31b installed in the drop port, and the optical switch 32d and 32c arranged on the add port side through the delay device 33 is paired. Are input to the add ports of the AWGs 32a and 32b. By doing so, the mixed signal output from the AWG 32b is output with a delay difference added to the phase-modulated optical signal. Here, in FIG. 16, the delay device 33 is inserted into the phase-modulated optical signal, but the routes of the intensity-modulated optical signal and the phase-modulated optical signal may be interchanged.

  Further, in the one shown in FIG. 17, on the propagation path of each demultiplexed light demultiplexed by the AWG 32a, the output (insertion) of the optical signal from the add port to the AWG 32b side and the through signal from the AWG 32a to the AWG 32b. An optical switch 32d and a delay device 32e capable of setting a detour path through the delay device 32e for each wavelength are provided on the upstream side of each optical switch 32c for switching the output (through) of each wavelength.

  That is, in the optical transmission apparatus shown in FIG. 17, the path through the delay device 33 is not set via the drop side AWG 31a as shown in FIG. 16, but the delay device 32e passes between the AWGs 32a and 32b. It is possible to set a route that does (or does not pass). Specifically, for the optical signal having the wavelength forming the phase-modulated optical signal, the control unit 3A similar to the case of FIG. 16 described above switches the optical switch 32d and sets a detour path that passes through the delay device 32e. For an optical signal having a wavelength that forms an intensity-modulated optical signal, the optical switch 32d is switched to set a path that is output to the optical switch 32c without passing through the delay device 32e.

In the optical transmission apparatus shown in FIGS. 16 and 17 configured as described above, the same advantages as those of the first embodiment can be obtained.
[A4] Description of the effects of the first embodiment and the first to third modifications of the first embodiment The effects of the first to third modifications derived from the first embodiment and the first embodiment were calculated. The model is shown in FIG. 18, and the results are shown in FIG.

  As shown in FIG. 18, the transmission line fiber 140 has a chromatic dispersion of 2.4 ps / nm / km and a repeater span of 80 km. In the optical transmission apparatus 111 as a repeater, an input wavelength multiplexed optical signal (mixed signal) is received. After the dispersion compensation is performed by the dispersion compensating fiber 29 and amplified by the optical amplifier 30a, the intensity-modulated optical signal and the phase-modulated optical signal are branched by the optical coupler 21a, and the delay device 22 is inserted into the phase-modulated optical signal. After giving a delay, it is multiplexed by a wavelength selective switch (WSS) 23. The output from the WSS 23 is amplified by the optical amplifier 30b and sent to the transmission line fiber 140.

  For the model shown in FIG. 18, the calculation results shown in FIG. 19 were obtained. That is, by adding a delay in each span, the worst Q penalty amount can be reduced by about 3 dB (when the chromatic dispersion compensation rate is 100%). Note that the delay amount difference between channels is related to chromatic dispersion, and depending on the amount of delay load, the bit arrangement may be aligned due to chromatic dispersion compensation deviation. Therefore, in each optical transmission device 111, it is desirable to give a delay difference sufficiently larger than the delay amount that is caused by the residual dispersion amount with respect to the dispersion amount in the transmission line fiber 140 compensated by the dispersion compensation fiber 29. For example, since the chromatic dispersion tolerance of a 10 Gbps transmission signal in the entire transmission path between the transmitter 112 and the receiver 113 is approximately ± 1000 ps / nm, assuming that the wavelength interval is 0.8 nm, optical transmission as each repeater In the device 111, it is safe if a delay of ± 800 ps or more is loaded in total.

[B] Description of Second Embodiment FIG. 20 is a block diagram showing an optical transmission apparatus 111A according to a second embodiment of the present invention. The optical transmission device 111A shown in FIG. 20 is different from the optical transmission device 111 (see FIG. 2) in the first embodiment in that a chromatic dispersion imparting device (bit time difference providing unit) 12A is used instead of the delay unit 12. The difference is that the delay block unit 1A is provided, and the configuration other than this is basically the same. In FIG. 20, the same reference numerals as those in FIG. 2 denote almost the same parts.

  That is, in the optical coupler 11 as the branching unit 11, the input mixed signal is branched into two, one is output as it is to the wavelength selective switch 13 as the multiplexing unit 13, and the other is further wavelength-converted in the chromatic dispersion adder 12 A. Give dispersion. As a result, the optical signal that is branched into two by the optical coupler 11 and directly input to the wavelength selective switch 13 and the optical signal that is input to the wavelength selective switch 13 after being provided with chromatic dispersion by the chromatic dispersion adder 12A. Then, a difference is provided in the amount of chromatic dispersion.

Therefore, at least two optical signals having relatively different bit time differences (through loading different chromatic dispersion amounts) are generated from the input wavelength multiplexed optical signal by the optical coupler 11 and the chromatic dispersion adder 12A. The bit time difference giving signal generating unit is configured.
In the wavelength selective switch 13, as described above, the optical signal branched and directly input by the optical coupler 11 and the optical signal via the chromatic dispersion adder 12A are input and output through the output port. Optical signals can be selectively switched for each wavelength and output.

  At this time, if the control unit 3 determines that the output destination transmission line fiber 140 is easily affected by XPM based on the management information collected by the information collecting unit 2, the wavelength selective switch 13 is turned on. By controlling, for example, an optical signal having a wavelength that forms a phase-modulated optical signal, an optical signal that has passed through the chromatic dispersion adder 12A is output through an output port, while an optical signal having a wavelength that forms an intensity-modulated optical signal is The path switching can be set so that an optical signal branched directly by the optical coupler 11 (without passing through the chromatic dispersion adder 12A) is output through the output port. As a result, a difference in bit delay time can be substantially provided between the phase-modulated optical signal and the intensity-modulated optical signal, and, as in the case of the first embodiment described above, red chirp remaining due to XPM can be reduced. It can be suppressed.

Therefore, the wavelength selective switch 13 described above receives the two optical signals from the optical coupler 11 and the chromatic dispersion adder 12A, and wavelength division multiplexing in which a bit time difference is given between the phase-modulated optical signal and the intensity-modulated optical signal. A wavelength-multiplexed optical signal output unit that generates and outputs an optical signal is configured.
In FIG. 20, the optical coupler 11 as a branching unit is provided and the wavelength selective switch 13 as a multiplexing unit is provided. However, according to the present invention, the optical coupler 11 is used instead of the optical coupler 11. It is also possible to provide a wavelength selective switch as a unit and to use a confluence element such as an optical coupler instead of the wavelength selective switch 13. Of course, as in the wavelength selective switches 15 and 15 ′ (see FIGS. 3 and 4) in the first embodiment, a single wavelength selective switch may have functions as a demultiplexing unit and a combining unit.

  In the optical transmission device 111A according to the second embodiment having the above-described configuration, the control unit 3 is easily affected by XPM in the transmission line fiber 140 based on the management information collected by the information collection unit 2. (Such as a fiber having a small chromatic dispersion value of the transmission line fiber), the phase-modulated optical signal and the intensity in the optical transmission apparatus 111A are controlled by controlling the wavelength selective switch 13 forming the delay block unit 1A. A chromatic dispersion difference is given to the modulated optical signal.

  As shown in the dispersion map (transmission distance vs. cumulative chromatic dispersion graph) shown in FIG. 21, in the optical transmission device 111A as each repeater, when the dispersion compensation rate in the dispersion compensation function unit is 100%, each optical transmission Since bit arrangements overlap in apparatus 111A, phase modulation received by XPM accumulates. On the other hand, as shown in FIG. 20, by changing the path in the optical transmission apparatus 111A and passing through the chromatic dispersion imparting device 12A that imparts chromatic dispersion to the phase-modulated optical signal, the dispersion map becomes as shown in FIG. Thus, the dispersion compensation rate in each optical transmission device 111A can be shifted from 100%. In this way, the bit arrangement does not overlap in each optical transmission device 111A, and therefore the cumulative amount of phase modulation by XPM decreases. Here, in FIG. 20, the chromatic dispersion adder 12A is inserted into the phase-modulated optical signal, but the route of the intensity-modulated optical signal and the phase-modulated optical signal may be interchanged.

  FIG. 23 shows a model for calculating the effect of the second embodiment, and FIG. 24 shows the calculation result. The model shown in FIG. 23 is different from the model shown in FIG. 18 in that a chromatic dispersion imparting device 12A is provided instead of the delay device 22. The transmission line fiber 140 has a chromatic dispersion of 2.4 ps / nm / km and a relay span of 80 km. In the optical transmission apparatus 111A, after the intensity-modulated optical signal and the phase-modulated optical signal are branched by optical couplers 21a and 21b serving as demultiplexing units, the wavelength-modulation adder 12A is inserted into the phase-modulated optical signal to give a delay. The wavelength selection switch (Wavelength Selective Switch, WSS) 23 is used as a multiplexing unit. As shown in the calculation result of FIG. 24, by shifting the dispersion compensation ratio between the intensity-modulated optical signal and the phase-modulated optical signal in each optical transmission device 111A from 100%, the bit arrangement receiving the XPM is changed to each repeater. Therefore, the accumulated amount of phase modulation by XPM can be reduced.

Thus, also in 2nd Embodiment of this invention, the same advantage as the case of the above-mentioned 1st Embodiment can be acquired by 12 A of wavelength dispersion imparting units and the multiplexing part 13. FIG.
[C] Description of Third Embodiment FIG. 25 is a block diagram showing an optical transmission apparatus (optical transmission apparatus) according to a third embodiment of the present invention. The optical transmitter shown in FIG. 25 is an optical transmitter that transmits wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line, and has at least one (here, a plurality of wavelengths) channels. An intensity-modulated optical signal generator 41 that generates a set intensity-modulated optical signal, a phase-modulated optical signal generator 42 that generates a phase-modulated optical signal in which at least one (here, a plurality of wavelengths) channels are set, And a chromatic dispersion imparting unit 43, multiplexers 44a to 44c, an information collecting unit 2 and a control unit 3B.

  Here, the multiplexer 44a multiplexes (wavelength multiplexes) the intensity-modulated optical signals from the intensity-modulated optical signal generation unit 41, particularly the intensity-modulated optical signals of a plurality of channels. Similarly, the multiplexer 44b multiplexes (wavelength multiplexes) the phase-modulated optical signal from the phase-modulated optical signal generator 42, particularly the phase-modulated optical signals of a plurality of channels.

  Further, the chromatic dispersion imparting unit 43 has a function as a chromatic dispersion imparting unit that blunts the rising / falling of the waveform of the intensity modulated optical signal generated by the intensity modulated optical signal generating unit 41, and the multiplexing unit 44a. The intensity-modulated optical signal (see A in FIG. 25) is output as an intensity-modulated optical signal (see B in FIG. 25) that is made to rise and fall by applying chromatic dispersion.

  Further, the multiplexer 44c multiplexes (wavelength multiplexes) the intensity-modulated optical signal to which the chromatic dispersion is imparted by the chromatic dispersion-imparting unit 43 and the phase-modulated optical signal from the multiplexer 44b, and the intensity-modulated optical signal and This is output as a mixed signal of phase-modulated optical signals. Therefore, the above-described multiplexers 44a to 44c constitute a multiplex transmitter that multiplexes and transmits the intensity-modulated optical signal from the chromatic dispersion adder 43 and the phase-modulated optical signal from the phase-modulated optical signal generator 42. .

  FIG. 26 is a block diagram showing another optical transmission apparatus in the third embodiment. The optical transmission apparatus shown in FIG. 26 includes, in addition to the one shown in FIG. 25, a chromatic dispersion adder 43b that applies chromatic dispersion to the phase-modulated optical signal from the multiplexer 44b, and the wavelength multiplexed light from the multiplexer 44c. Further provided is a chromatic dispersion imparting unit 43c for imparting chromatic dispersion for overcompensation in the transmission path to the signal (mixed signal).

  FIG. 27 is a block diagram showing another optical transmission apparatus in the third embodiment. The optical transmitter shown in FIG. 27 differs from the optical transmitter shown in FIGS. 25 and 26 in that the intensity-modulated optical signal generated by the intensity-modulated optical signal generator 41 instead of the chromatic dispersion adders 43, 43b, and 43c 25 and 26, a pre-equalization processing unit 45 for performing pre-equalization processing in the electric signal stage corresponding to the channel is provided so that the intensity-modulated optical signal has a smooth waveform as shown in FIGS. That is, the pre-equalization processing unit 45 constitutes a chromatic dispersion providing unit that blunts the rise / fall of the waveform of the intensity modulated optical signal generated (to be generated) by the intensity modulated optical signal generating unit.

In the optical transmission apparatus according to the third embodiment of the present invention having the above-described configuration, dispersion is loaded on the generated intensity-modulated optical signal, and the mixed signal is transmitted by smoothing the transmission waveform of the intensity-modulated optical signal. That is, since the rise time and fall time of the intensity-modulated optical signal waveform become longer, the intensity change amount becomes smaller, and the effect of XPM becomes smaller.
28 (a) to 28 (e) and 29 (a) to 29 (e) suppress the influence of cross-phase modulation at the signal receiving end by adding chromatic dispersion to the intensity modulated optical signal. It is a figure for demonstrating what can be done. As shown in FIGS. 28 (c) and 29 (c), the phase-modulated optical signal and the intensity are transmitted to a network in which the optical transmission device 150 is connected in multiple stages by a transmission device 160 including a transmission line fiber 140 and an optical amplifier. Assume that a mixed signal with a modulated optical signal is transmitted.

  Then, as the mixed signal transmitted by the optical transmission device 150, when the mixed signal is transmitted without the intensity modulated optical signal having a rounded waveform, for example, as shown in FIGS. 28 (a) and 28 (b). A bit placement model can be assumed. That is, as shown in FIG. 28 (c), in one transmission section (one span) from the optical transmission device 150 to the next relay device 160, the propagation speed of the phase-modulated optical signal by 4 bit times of the intensity-modulated optical signal. When the signal is fast, it is possible to assume a mode of overtaking at the bit waveform level of the intensity-modulated optical signal of the phase-modulated optical signal as shown in FIGS. 28 (a) and 28 (b).

  That is, as shown in FIG. 28 (d), the phase-modulated optical signal overtakes the rising and falling of the intensity-modulated optical signal one by one on the upstream side of the transmission line fiber 140 even during one span (red chirp and blue). (Chirping), overtaking the rise of the intensity-modulated optical signal in the middle stream (occurring red chirp), and at the input point to the next relay stage, the falling edge of the bit of the intensity-modulated optical signal 4 bits ahead at the time of transmission The falling edge of the phase-modulated optical signal is aligned (occurrence of blue chirp).

  In other words, as the bit arrangement of the mixed signal transmitted from the optical transmission device 150, as shown in FIGS. 28 (a) and 28 (b), the relative bit arrangement of the intensity-modulated optical signal and the phase-modulated optical signal is shown. It can be assumed that the relationship is complete. In this case, as shown in FIG. 28 (e), residual chirp in each relay section is accumulated, so that the signal receiving end is affected by XPM.

  On the other hand, when chromatic dispersion for smoothing the waveform is applied to the intensity-modulated optical signal, for example, as shown in FIGS. 29 (a) and 29 (b), the relativeness of the intensity-modulated optical signal and the phase-modulated optical signal Even if there is a general bit arrangement relationship, as shown in FIG. 29 (c), the occurrence of red chirp and blue chirp generated on the transmission line fiber 140 is the same as in the case of FIG. 28 (d). Therefore, the amount of residual chirp accumulated in the relay section can also be reduced as shown in FIG.

  As described above, according to the third embodiment of the present invention, the chromatic dispersion imparting unit 43 can reduce the occurrence of chirp due to XPM on the transmission line, thereby suppressing the influence of XPM at the signal receiving end. Therefore, there is an advantage that deterioration of transmission quality can be suppressed in a network system in which intensity modulated optical signals and phase modulated optical signals are mixed. In addition, because it is possible to easily upgrade a transmission system using phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected, and network management flexibility can be increased. it can.

In the third embodiment, chromatic dispersion is applied to smooth the waveform of the intensity-modulated optical signal generated in the optical transmitter, but according to the present invention, for example, in an optical repeater that performs regenerative relay, It is good also as a structure which has the function to provide the wavelength dispersion which makes a waveform smooth the intensity | strength modulation optical signal to produce | generate.
Furthermore, the dispersion imparting aspect in the second embodiment described above and the dispersion imparting aspect in the third embodiment can be implemented in combination. FIG. 31 shows an example of a dispersion map in the case where the modes of imparting dispersion in the second embodiment and the third embodiment are combined. FIG. 30 shows a dispersion map as a comparison. In the dispersion map in FIG. 30, both the intensity-modulated optical signal and the phase-modulated optical signal have a chromatic dispersion compensation rate of 100%, whereas in the dispersion map in FIG. In the chromatic dispersion imparting device 12A in the optical transmission apparatus 111A as each relay apparatus, the chromatic dispersion compensation rate for the intensity-modulated optical signal is shifted from 100%. By doing so, it is possible to suppress waveform deterioration due to XPM while ensuring the transmission characteristics of the intensity-modulated optical signal over as long a distance as possible.

[D] Description of Fourth Embodiment FIG. 32 is a diagram showing a configuration of a data transfer network to which an optical transmission apparatus according to a fourth embodiment of the present invention is applied. As shown in FIG. The data transfer network 110C in FIG. 1 is also applied as the data transfer network (reference numeral 110) shown in FIG. 1, and the optical transmission apparatuses 111C-1 to 111C-5 have transmission line fibers having a small dispersion value (for example, NZDSF) 140 are connected in a ring shape, and the optical transmission apparatuses 111C-4 to 111C-8 are also connected in a ring shape through a transmission line fiber (for example, NZDSF) 140 having a relatively small dispersion value.

In the data transfer network 110C having such a configuration, the mixed signal of the intensity-modulated optical signal and the phase-modulated optical signal input to the optical transmission device 111-2 is the optical transmission device 111C-3, 111C-4, 111C-. Assume a case where relay transmission is sequentially performed through 8 and 111C-7 (see A in FIG. 32).
At this time, focusing on the relay processing in the optical transmission device 111C-4, in the optical transmission device 111C-4, one of the intensity-modulated optical signal and the phase-modulated optical signal among the input mixed signals ( For example, the intensity-modulated optical signal) is relayed to the optical transmission apparatuses 111C-8 and 111C-7 via a detour (see B in FIG. 32) formed with the optical transmission apparatus 111C-5. It is like that.

That is, in the optical transmission device 111C-4, by cooperating with the optical transmission device 111C-5, the route of the intensity modulated optical signal and the phase modulated optical signal is changed to give a delay difference between the two signals. Therefore, in this case as well, the influence of XPM at the receiving end can be suppressed as in the case of the first embodiment described above.
FIG. 33 is a block diagram showing a configuration of an optical transmission device 111C that can set a bypass as described above. As shown in FIG. 33, the optical transmission device 111C includes optical couplers 51 and 52 and wavelength selective switches 53 to 56, and the information collection unit 2 and the control basically similar to those in the first embodiment described above. Part 3C is provided.

  The optical coupler 51 splits the input mixed signal (intensity modulated optical signal and phase modulated optical signal) into three branches, one to the wavelength selective switch 53 guided to the output destination transmission line fiber 140 and the other dropped. Are output to an add port of the wavelength selective switch 54 led to the transmission line fiber 140 forming a detour route.

  Hereinafter, paying attention to the optical transmission device 111C-4 that relays and transmits the mixed signal transmitted through the path shown in FIG. 32A, the optical coupler 51 forms the first branched light of the mixed signal as the relay path A. To the wavelength selective switch 53 guided to the transmission line fiber 140 connected to the optical transmission device 111C-8, the second branched light to the drop wavelength selective switch 55, and the third branched light to the detour route (optical transmission device (Path to 111C-5) is output to the add port of the wavelength selective switch 54 guided to the transmission line fiber 140 forming B.

  The optical coupler 52 is connected to the transmission line fiber 140 that forms the detour route B (between the optical transmission device 111C-5) and the optical signal from the transmission line fiber 140 that forms this detour route B is divided into three branches. One is to the add port of the wavelength selective switch 53 guided to the transmission line fiber 140 forming the output destination route A, the other is to the wavelength selective switch 56 for dropping, and the other is the detour route B. Each is output to the wavelength selective switch 54 guided to the transmission line fiber 140.

  Further, the wavelength selective switch 53 receives a mixed signal that has propagated through the upstream transmission line fiber 140 forming the relay path A, which is a branched light from the optical coupler 51, and receives a branched light from the optical coupler 52. An optical signal from a transmission line fiber 140 forming a detour route B is input through an add port, and an optical signal having a wavelength to be relayed and transmitted to the downstream transmission line fiber 140 forming the relay path A is selectively switched and output. To do.

Further, the wavelength selective switch 54 receives an optical signal from the transmission line fiber 140 forming the detour route B from the optical coupler 52, and also receives the branched light from the optical coupler 51 from the add port and outputs from the output port. The wavelength to be output can be selectively switched.
The control unit 3 </ b> C sets and controls the path switching for each wavelength of the wavelength selective switches 53 to 56 based on the management information collected by the information collecting unit 2. For example, when it is determined that the transmission line fiber 140 forming the transmission destination path is easily affected by XPM based on the management information from the information collection unit 2, the control unit 3C has the above-described wavelength selective switches 53 and 54. By controlling the path switching setting for each wavelength, a bypass route B is set with the optical transmission device 111C-5 for the bypass transmission of the intensity modulated optical signal.

Specifically, by controlling the wavelength selective switch 54, one of the intensity-modulated optical signal and the phase-modulated optical signal among the mixed signals from the optical coupler 51 input through the add port (in the case of FIG. 33). Transmits an optical signal having a wavelength corresponding to the intensity modulated optical signal) to the detour route B.
Further, by controlling the wavelength selective switch 53, either the intensity-modulated optical signal or the phase-modulated optical signal among the mixed signals input from the optical coupler 51 (phase-modulated optical signal in the case of FIG. 33). Is transmitted to the downstream relay path A, while the intensity modulated optical signal from the optical coupler 52 (via the detour route B) input from the add port is transmitted to the downstream relay path A. Send it out.

  Therefore, the optical coupler 51, the wavelength selective switch 53, and the wavelength selective switch 54 described above cooperate to function as a separation unit that separates the intensity-modulated optical signal and the phase-modulated optical signal in the input wavelength multiplexed signal. Realize. Further, the wavelength selective switch 54 constitutes a detour sending unit that sends one of the intensity-modulated optical signal and the phase-modulated optical signal separated by the demultiplexing unit to the detour. Further, by cooperation of the optical couplers 51 and 52 and the wavelength selective switch 53, any one of the intensity-modulated optical signal and the phase-modulated optical signal input through the detour, and the intensity-modulated optical signal and the phase from the separation unit are combined. A wavelength division multiplex repeater that multiplexes and repeats one of the modulated optical signals with the other is configured.

  In the optical transmission apparatus 111C-4 shown in FIG. 32 configured as described above, as shown in FIG. 33, the downstream transmission line fiber forming the relay path A based on the management information collected by the information collection unit 2 140, after recognizing that it is susceptible to the influence of XPM (such as a fiber having a small chromatic dispersion value of the transmission line fiber 140), the path to the wavelength selective switches 53 and 54 in the control unit 3C By performing switching control, the route of the intensity-modulated optical signal and the phase-modulated optical signal is changed, and a delay difference is given between the two signals.

  That is, the wavelength and the modulation method are made to correspond one-to-one, and the wavelength is switched using the wavelength selective switches 53 and 54, thereby routing the optical signal according to the modulation method. As a result, as shown in FIG. 33, the intensity-modulated optical signal is delayed after being routed via the bypass route B, and then multiplexed, whereby the bit arrangement of the phase-modulated optical signal and the intensity-modulated optical signal is changed to each of the subsequent stages. Since the optical transmission apparatuses 111C-8 and 111C-7 do not overlap, the accumulated amount of phase modulation by XPM can be reduced.

  As described above, according to the optical transmission device according to the fourth embodiment of the present invention, the detour route setting unit can set a detour route between one of the intensity-modulated optical signal and the phase-modulated optical signal. Since a bit time difference can be provided between the intensity modulated optical signal and the phase modulated optical signal, the intensity modulated optical signal and the detour route via the detour route can be set as in the case of the first embodiment. Since the phase-modulated optical signal that does not pass through is wavelength-multiplexed and transmitted, the accumulation of red chirp can be reduced as compared to the case where both modulated signals are transmitted without going through the detour route. Since the influence of XPM can be suppressed, it is possible to suppress deterioration in transmission quality in a network system in which intensity modulated optical signals and phase modulated optical signals are mixed.

In addition, because it is possible to easily upgrade a transmission system using phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected, and network management flexibility can be increased. it can.
[E] Description of Fifth Embodiment FIG. 34 is a diagram showing the configuration of a data transfer network to which an optical transmission apparatus according to a fifth embodiment of the present invention is applied. As shown in FIG. In the data transfer network 110D, optical transmission apparatuses 111D-1 to 111D-3 are connected and connected via a fiber (for example, single mode fiber, SMF) 141 having a relatively large dispersion value, and the optical transmission apparatus 111D-1 , 111D-4 and 111D-3 are connected via a fiber (for example, NZDSF) 142 having a relatively small dispersion value.

  That is, in the data transfer network 110D having such a configuration, when the wavelength multiplexed optical signal input to the optical transmission device 111D-1 is output to the optical transmission device 111D-3, the route via the SMF 141 described above and Any of the routes via the NZDSF 142 can be used. As described above, when an intensity-modulated optical signal and a phase-modulated optical signal are mixed in a wavelength-multiplexed optical signal, when an optical fiber having a relatively small dispersion value such as NZDSF 142 is transmitted, between these signals Since the walk-off at is small, it is determined that it is easily affected by XPM at the receiving end. Therefore, when transmitting such mixed signals that are easily affected by XPM, the effect of XPM at the receiving end is reduced by relay transmission to the optical transmission device 111D-3 via the route on the SMF 141 side. To be able to.

On the other hand, depending on the modulation method and wavelength arrangement of each channel in the input wavelength division multiplexed signal, if it can be assumed that the reception quality can be made better through the NZDSF 142 than the SMF 141, the route on the NZDSF 142 side It is also possible to perform relay transmission to the optical transmission device 111D-3 via the.
FIG. 35 is a block diagram showing a configuration of an optical transmission apparatus 111D having a function of determining a route via as described above. As shown in FIG. 35, the optical transmission device 111D includes optical couplers 61 and 62 and wavelength selective switches 63 to 66, and an information collecting unit 2 and a control basically similar to those in the first embodiment described above. Provide part 3D.

  35 includes an optical coupler 62, a wavelength selective switch 64, and a drop wavelength selective switch 66 as a relay transmission system using the SMF 141, and an optical transmission device 111D as a relay transmission system using the NZDSF 142. A coupler 61, a wavelength selective switch 63, and a drop wavelength selective switch 65 can be provided.

  The optical coupler 61 branches the input wavelength multiplexed optical signal (for example, a mixed signal of intensity modulated optical signal and phase modulated optical signal) into three branches, one to the wavelength selective switch 63 led to the NZDSF 142 and the other to the drop. Are output to an add port of the wavelength selective switch 64 led to the SMF 141.

  In the following, paying attention to the case where a wavelength-multiplexed optical signal is relayed from the optical transmission device 111D-1 to the optical transmission device 111D-3 shown in FIG. 34, the optical coupler 61 performs the first operation on the input wavelength-multiplexed optical signal. Are output to the wavelength selective switch 63 guided to the NZDSF 142, the second branched light to the wavelength selective switch 65 for dropping, and the third branched light to the add port of the wavelength selective switch 64 guided to the SMF 141, respectively. It has come to be.

  The optical coupler 62 is connected to an upstream transmission line fiber (for example, SMF) different from the optical coupler 61, and the optical signal from the upstream transmission line fiber is branched into three, and one is guided to the NZDSF 142. The wavelength selection switch 63 is output to the add port, the other is output to the wavelength selection switch 66 for dropping, and the other is output to the wavelength selection switch 64 led to the SMF 141.

  Further, the wavelength selective switch 63 receives the branched light from the optical coupler 61 and also receives the branched light from the optical coupler 62 through the add port, and selectively switches the optical signal having the wavelength to be relayed to the NZDSF 142. . The wavelength selective switch 64 receives the branched light from the optical coupler 62 and also receives the branched light from the optical coupler 61 from the add port, and selectively selects an optical signal having a wavelength to be relayed to the SMF 141. Switch.

Therefore, the above-described optical coupler 61, wavelength selective switch 63, and wavelength selective switch 64 cooperate to provide a path switching unit that selectively switches the transmission path that is the transmission destination path for the input wavelength multiplexed signal light. Configure.
The control unit 3D sets and controls the path switching for each wavelength of the wavelength selective switches 63 to 66 based on the management information collected by the information collecting unit 2.

  For example, based on management information from the information collecting unit 2, based on information on a combination of modulation schemes of input wavelength multiplexed optical signals (presence / absence of mixing of intensity modulated optical signals and phase modulated optical signals) and wavelength arrangement thereof When it is determined that the receiving end is easily affected by XPM, the control unit 3D controls the path switching setting for each wavelength in the wavelength selective switches 63 and 64, so that the XPM at the receiving end is controlled. A route passing through the SMF 141 is set as a route for suppressing the influence of.

Specifically, the mixed signal from the optical coupler 61 is sent to the SMF 141 by controlling the wavelength selective switch 64. On the other hand, by controlling the wavelength selective switch 63, transmission of mixed signals input from the optical coupler 61 to the NZDSF 142 is blocked (blocked).
When it is determined that the route of the NZDSF 142 is more appropriate than the route of the SMF 141 based on the management information from the information collecting unit 2, the control unit 3D uses the wavelength at the wavelength selective switches 63 and 64 described above. By controlling the route switching setting for each, a route passing through the NZDSF 142 is set, and the route to the SMF 141 is blocked.

In other words, the control unit 3D controls the route switching setting to the SMF 141 or the NZDSF 142 by the wavelength selective switches 63 and 64 as the route switching unit based on the management information collected by the information collecting unit 2.
As described above, according to the fifth embodiment of the present invention, the route by the wavelength selective switches 63 and 64 as the route switching unit based on the management information collected by the information collecting unit 2 by the control unit 3D. Since the switching setting can be controlled, when it is easily affected by XPM at the receiving end, it is possible to adaptively switch to a route that minimizes the influence, and to suppress deterioration in transmission quality. There are advantages. In addition, because it is possible to easily upgrade a transmission system using phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected, and network management flexibility can be increased. it can.

[F] Description of Sixth Embodiment FIG. 36 is a diagram showing a configuration of a data transfer network to which an optical transmission apparatus according to a sixth embodiment of the present invention is applied. As shown in FIG. 36, in the data transfer network 110E according to the sixth embodiment, optical transmission apparatuses 111E-1 to 111E-4 are connected to each other in a ring shape via a fiber (for example, NZDSF) 142 having a relatively small dispersion value. Are connected to each other.

That is, in the data transfer network 110E having such a configuration, when the wavelength multiplexed optical signal input to the optical transmission device 111E-1 is output to the optical transmission device 111E-3, the optical transmission device 111E-2 is routed through the optical transmission device 111E-2. The route (see A in FIG. 36) and the route via the optical transmission device 111E-4 (see B in FIG. 36) can be used.
In the optical transmission apparatus 111E according to the sixth embodiment, as shown in FIG. 37, a configuration basically similar to that of the optical transmission apparatus 111D in the fifth embodiment described above (reference numerals 61 to 66, 2, 3D in FIG. 35). If the input wavelength-multiplexed optical signal is a mixed signal of an intensity-modulated optical signal and a phase-modulated optical signal, the destination is the phase-modulated optical signal and the intensity-modulated optical signal that form these mixed signals. The routes are determined to be different routes (routes A and B when paying attention to the optical transmission device 111E-1 in FIG. 36), and thereby, a mixed signal of intensity-modulated optical signal and phase-modulated optical signal This makes it possible to suppress the influence of XPM at the receiving end due to the transmission.

  Therefore, also in the sixth embodiment, when it is easily affected by XPM at the receiving end, it is possible to adaptively switch to a route that minimizes the influence, and it is possible to suppress deterioration in transmission quality. There is. In addition, because it is possible to easily upgrade a transmission system using phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected, and network management flexibility can be increased. it can.

When the route of the network system is duplicated, the phase-modulated optical signal and the intensity-modulated optical signal may be assigned to the main route and the backup route for routing.
[G] Description of Seventh Embodiment FIG. 38 is a diagram showing a configuration of a data transfer network to which an optical transmission apparatus according to a seventh embodiment of the present invention is applied. As shown in FIG. As in the data transfer network 110D in the fifth embodiment described above, the data transfer network 110F in FIG. 1 is connected to optical transmission apparatuses 111F-1 to 111F-3 via a fiber (for example, SMF) 141 having a relatively large dispersion value. At the same time, the optical transmission apparatuses 111F-1, 111F-4, and 111F-3 are connected and connected via an optical fiber (for example, NZDSF) 142 having a relatively small dispersion value.

  That is, in the data transfer network 110F having such a configuration, when the wavelength multiplexed optical signal input to the optical transmission device 111F-1 is output to the optical transmission device 111F-3, the route via the SMF 141 described above and Any of the routes via the NZDSF 142 can be used. As described above, when an intensity-modulated optical signal and a phase-modulated optical signal are mixed in a wavelength-multiplexed optical signal, when an optical fiber having a relatively small dispersion value such as NZDSF 142 is transmitted, between these signals Since the walk-off at is small, it can be assumed that it is easily affected by XPM at the receiving end.

Therefore, in the optical transmission device 111F according to the seventh embodiment, when the mixed signal as described above is transmitted through such a path of the NZDSF 142, the phase-modulated optical signal and the adjacent intensity-modulated optical signal that are easily affected by XPM. The wavelength arrangement is changed.
FIG. 39 is a block diagram showing an optical transmission apparatus 111F having a function of changing the wavelength arrangement described above. As shown in FIG. 39, the optical transmission apparatus 111F has the same information as in the case of the first embodiment described above, together with the wavelength arrangement conversion unit 70 including the duplexer 71, the wavelength converter 72, and the multiplexer 73. A collection unit 2 and a control unit 3F are provided.

  Note that when applied as the optical transmission device 111F-1 in FIG. 38, the SMF 141 and the NZDSF 142 can be configured to switch the output destination path in units of wavelengths. In this case, FIG. The wavelength arrangement conversion unit 70 shown in FIG. 39 may be provided between the wavelength selective switch 63 and the NZDSF 142 in FIG. 35.

  Here, the demultiplexer 71 is a separation unit that separates an optical signal in a part of the wavelength band in the input wavelength division multiplexed signal from an optical signal in another wavelength band, for example, for control from the control unit 3F. Accordingly, it can be configured by a wavelength selective switch that switches the output route for each wavelength. In particular, some separated optical signals can be configured to propagate different paths for each channel.

  The wavelength converter 72 constitutes a wavelength assignment changing unit that changes the wavelength assignment for the intensity-modulated optical signal in a part of the wavelength band separated by the branching filter 71. For example, the assumed part of the wavelength According to the number of wavelengths of the optical signal in the band, a pair of optical / electrical conversion elements and electrical / optical conversion elements having different conversion wavelengths is arranged in parallel. As a result, the optical signals of some wavelength bands separated by the duplexer 71 can be converted into optical signals having different converted wavelengths according to the number of wavelengths of the conversion source.

In addition, although it is possible to separate the optical signal having the wavelength applied to the phase-modulated optical signal in the demultiplexer 71, in this case, the wavelength converter 72 once demodulates the separated phase-modulated optical signal. Thereafter, the optical signal having a wavelength different from the wavelength of the conversion source is again subjected to phase modulation.
Further, as a mode of changing the wavelength assignment in the wavelength converter 72 described above, as shown in FIG. 38A, only the channel of the phase-modulated optical signal P that is easily affected by XPM has a relatively long dispersion value. By shifting to an unused channel on the wavelength side (preferably an adjacent channel is an unused channel), the influence of XPM can be suppressed. As shown in FIG. 38B, phase-modulated light that is easily affected by XPM. By shifting the channel of the intensity modulated optical signal I adjacent to the signal to an unused channel (for example, a channel on the long wavelength side), a substantial guard band for the channel of the phase modulated optical signal can be provided. Further, as shown in FIG. 38C, the phase-modulated optical signal P that is easily affected by XPM and the channel of the intensity-modulated optical signal I adjacent to the phase-modulated optical signal P are combined into a long wavelength side with a large dispersion value. By shifting to this channel, the influence of XPM can be suppressed.

Furthermore, the multiplexer 73 wavelength-multiplexes the optical signal whose wavelength assignment has been changed by the wavelength converter 72 and the optical signal of another wavelength band whose wavelength assignment from the demultiplexer 71 has not been changed. This is a wavelength multiplexing repeater that repeats, and can be constituted by, for example, an optical coupler.
In the optical transmission device 111F configured as described above, the control unit 3F is easily affected by XPM in the output destination transmission line fiber based on the management information collected by the information collection unit 2 (output) In the section where the previous transmission line fiber is a fiber that has a small chromatic dispersion value such as NZDSF142) and is susceptible to the influence of the XPM, the wavelength between the intensity-modulated optical signal and the phase-modulated optical signal In order to change the wavelength arrangement so as to suppress the nonlinear effect, the path guided to the wavelength converter 72 in the wavelength selective switch 71 is switched for each wavelength.

By increasing the wavelength interval and the chromatic dispersion in this way, the walk-off between signals can be increased, so that the cumulative amount of phase modulation can be reduced.
Therefore, the seventh embodiment is also advantageous in that the influence of XPM at the receiving end can be reduced and transmission quality deterioration can be suppressed. In addition, because it is possible to easily upgrade a transmission system using phase-modulated optical signals, system performance (frequency utilization efficiency, optical signal-to-noise ratio characteristics, etc.) can be expected, and network management flexibility can be increased. it can.

[H] Description of Eighth Embodiment FIG. 40 is a block diagram showing an optical transmission apparatus 111G according to an eighth embodiment of the present invention. The optical transmission apparatus 111G shown in FIG. 40 also repeats and transmits wavelength-division multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line, but is almost the same as that in the seventh embodiment. Are provided with an interleaver demultiplexer 81, a delay unit 82, and an interleaver multiplexer 83.

  Here, the wavelength allocation converter 70 converts the wavelength allocation so that the intensity-modulated optical signal and the phase-modulated optical signal in the input wavelength-multiplexed signal are alternately wavelength-allocated, and outputs the wavelength-multiplexed optical signal. To do. For this reason, the wavelength converter 72 can be configured to have a wavelength conversion function for all wavelength channels for each modulation method (intensity modulated optical signal and phase modulated optical signal).

  In addition, the interleaver demultiplexer (interleaver demultiplexing unit) 81 has two sets of wavelengths, one set of wavelength pairs every other wavelength, for the wavelength multiplexed optical signal that has been converted by the wavelength allocation converter 70. Divide into groups. That is, since the wavelength arrangement conversion unit 70 converts the wavelength arrangement into a different wavelength arrangement every other wavelength, one set of wavelength groups is grouped into an optical signal having a wavelength of an intensity modulated optical signal, The other set of wavelength groups is grouped into optical signals having the wavelength of the phase-modulated optical signal.

  The delay unit 82 is a bit time difference providing unit that applies a relatively different bit time difference to the two wavelength groups divided by the interleaver demultiplexing unit 81. In the example shown in FIG. The interleaver multiplexer at the subsequent stage with respect to the optical signal of any one of the two wavelength groups divided by the demultiplexing unit 81 (that is, any one group of the intensity modulated optical signal and the phase modulated optical signal) A predetermined delay time is given to the timing of output to 83.

Further, the interleaver multiplexer 83 multiplexes and outputs one group of optical signals delayed by the delay unit 82 and a group of optical signals not delayed by the delay unit 82. The interleaver multiplexing unit multiplexes and outputs the optical signals of the two wavelength groups from the bit time difference adding unit.
In the optical transmission device 111G according to the eighth embodiment configured as described above, the wavelength arrangement conversion unit 70 nests the wavelength arrangements of the intensity-modulated optical signal and the phase-modulated optical signal so as to be an even channel and an odd channel, respectively. After changing the allocated wavelength in this way, the interleaver demultiplexer 81 performs block division on the phase-modulated optical signal and the intensity-modulated optical signal. For example, a delay difference is given to the phase-modulated optical signal through the delay unit 82. Thereby, when the optical transmission device 111G is connected and connected through an optical fiber having a relatively small dispersion value, each optical transmission device 111G can provide a delay difference between the intensity-modulated optical signal and the phase-modulated optical signal. Since the bit arrangement between the signals at the output of each optical transmission device does not overlap, the cumulative amount of phase modulation by XPM is reduced, and the waveform deterioration of the phase modulated optical signal can be suppressed.

Therefore, in the eighth embodiment, the same advantages as in the case of the first embodiment described above can be obtained.
[I] Description of Ninth Embodiment FIG. 41 is a block diagram showing an optical transmission apparatus 111H according to a ninth embodiment of the present invention. The optical transmission device 111H shown in FIG. 41 also repeats and transmits wavelength-division multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line, but is substantially the same as that in the first embodiment described above. And an optical amplifier 91, an optical demultiplexer 92, a variable attenuator (VOA) 93, a multiplexer 94, and an optical signal to be transmitted through a transmission line fiber. Is provided with an optical amplifier 95 and a control unit 3H.

  The demultiplexer 92 demultiplexes the wavelength multiplexed signal input through the optical amplifier 91 for each wavelength (channel), and separates the intensity modulated optical signal and the phase modulated optical signal in the wavelength multiplexed optical signal. It is. The VOA 93 is provided corresponding to the channel demultiplexed by the demultiplexer 92 and can give a variable attenuation amount for the optical signal for each channel. The phase-modulated optical signal separated by the demultiplexing unit 92 is provided. And an intensity difference applying unit that applies an intensity difference to the intensity modulated optical signal.

The multiplexer 94 multiplexes (wavelength multiplexes) the optical signals of the respective channels that are variably attenuated by the VOA 93, and combines the intensity-modulated optical signal and the phase-modulated optical signal to which the intensity difference is given by the VOA 93. This is a wavelength multiplexing repeater for wavelength multiplexing and relaying. The wavelength multiplexed optical signal multiplexed by the multiplexing unit 94 is sent to the transmission line fiber through the optical amplifier 95.
Based on the management information collected by the information collection unit 2, the control unit 3H is in a state that is easily affected by XPM in the transmission line fiber (such as a fiber having a small chromatic dispersion value of the transmission line fiber). After the recognition, the output power of the optical transmission device 111H of the intensity modulated optical signal and the phase modulated optical signal is reduced to suppress the influence of the nonlinear effect.

  Specifically, by controlling the attenuation amount of each VOA 93, the control unit 3H controls the attenuation amount in the VOA 93 corresponding to the channel related to the intensity modulated optical signal and the VOA 93 corresponding to the channel related to the phase modulated optical signal. Are different from each other (for example, the attenuation amount of the intensity-modulated optical signal is larger than the attenuation amount of the phase-modulated optical signal). By doing this, XPM, which is a nonlinear effect that occurs in the transmission line fiber, can be suppressed in substantially the same manner as in the case of the third embodiment described above, and therefore, between the phase-modulated optical signal and the intensity-modulated optical signal. XPM can be suppressed and waveform deterioration due to XPM of the phase-modulated optical signal can be reduced.

Further, by adjusting the pumping light power of the repeater, it is possible to give a power difference between the phase-modulated optical signal and the intensity-modulated optical signal, and to reduce waveform deterioration due to XPM of the phase-modulated optical signal.
[J] Others Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention described in the claims of the present invention.

For example, each of the above embodiments may be applied independently, or some embodiments may be combined and applied as shown in part.
Moreover, it is possible for those skilled in the art to manufacture the apparatus of the present invention based on the disclosure of the above-described embodiment.
[K] Appendix (Appendix 1)
An optical transmission device that transmits a wavelength-multiplexed optical signal of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
A bit time difference giving signal generator for generating at least two optical signals having relatively different bit time differences from the input wavelength-multiplexed optical signal;
The at least two optical signals from the bit time difference giving signal generation unit are inputted, and a wavelength multiplexed optical signal to which the bit time difference is given between the phase modulated optical signal and the intensity modulated optical signal is generated and outputted. An optical transmission device comprising a wavelength division multiplexing optical signal output unit.

(Appendix 2)
The bit time difference giving signal generation unit is configured to generate an optical signal to which a time difference due to delay is given as the two optical signals at a timing inputted to the wavelength multiplexed signal output unit. The optical transmission apparatus according to appendix 1.
(Appendix 3)
The bit time difference providing signal generation unit is configured to generate, as the two optical signals, optical signals loaded with different chromatic dispersion amounts as the two optical signals. Optical transmission equipment.

(Appendix 4)
The bit time difference giving signal generator is
A branching unit for branching the input wavelength multiplexed optical signal;
The optical transmission device according to appendix 1, further comprising: a bit time difference providing unit that applies a different bit time difference to each optical signal branched by the branching unit.

(Appendix 5)
The optical transmission apparatus according to appendix 4, wherein the wavelength division multiplexing optical signal output unit is configured by a wavelength selective switch.
(Appendix 6)
An information collection unit that collects network management information related to characteristics of transmission lines constituting a network to which the optical transmission device is applied and a modulation method of a transmission optical signal;
The optical transmission apparatus according to appendix 5, further comprising: a control unit that controls wavelength selection by the wavelength selective switch based on the management information collected by the information collection unit.

(Appendix 7)
The bit time difference giving signal generator is
A separation unit that separates the input wavelength-multiplexed optical signal into the phase-modulated optical signal and the intensity-modulated optical signal;
The optical transmission device according to appendix 1, further comprising: a bit time difference providing unit that applies a different bit time difference to each optical signal separated by the separation unit.

(Appendix 8)
The optical transmission apparatus according to appendix 7, wherein the wavelength-multiplexed optical signal output unit is configured as a merging unit that merges the optical signals to which the bit time difference is given by the bit time difference giving unit.
(Appendix 9)
An information collection unit that collects network management information related to characteristics of transmission lines constituting a network to which the optical transmission device is applied and a modulation method of a transmission optical signal;
The optical transmission device according to appendix 7, further comprising: a control unit that controls separation of an optical signal in the separation unit based on the management information collected by the information collection unit.

(Appendix 10)
The optical transmission apparatus in an optical communication system in which the optical transmission apparatus that transmits the wavelength multiplexed signal light is connected in multiple stages via a transmission line,
Each optical transmission device
A dispersion compensation unit that compensates for chromatic dispersion of wavelength multiplexed signal light input through the upstream optical transmission line is provided.
The bit time difference giving signal generating unit is substantially more than the residual dispersion amount after the compensation in the dispersion compensating unit is performed on the intensity modulated optical signal and the phase modulated optical signal from the dispersion compensating unit. The optical transmission apparatus according to appendix 1, wherein the optical transmission apparatus is configured to generate an optical signal having the bit time difference so as to give a large time difference to

(Appendix 11)
The optical transmission device according to appendix 1, further comprising an amplifying unit for amplifying the wavelength multiplexed optical signal from the wavelength multiplexed optical signal output unit.
(Appendix 12)
The optical transmission device that transmits the wavelength multiplexed signal light is connected in multiple stages via a transmission line, and each optical transmission device compensates for the wavelength dispersion of the wavelength multiplexed signal light input through the upstream optical transmission line. The optical transmission apparatus in an optical communication system provided with a compensation unit,
The bit time difference of each optical signal generated by the bit time difference giving signal generation unit is the same as that of the wavelength-multiplexed signal light with respect to the intensity-modulated optical signal and the phase-modulated optical signal output from the wavelength-multiplexed optical signal output unit. The optical transmission apparatus according to appendix 1, wherein the optical transmission apparatus is a time difference that gives a time difference substantially larger than an allowable amount of residual dispersion at the receiving end.

(Appendix 13)
The optical transmission apparatus according to any one of appendices 1 to 12, wherein the transmission path is a dispersion-shifted fiber.
(Appendix 14)
An optical transmission device that transmits wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
An intensity-modulated optical signal generator for generating the intensity-modulated optical signal;
A phase-modulated optical signal generator for generating the phase-modulated optical signal;
A chromatic dispersion providing unit for slowing the waveform rising / falling of the intensity modulated optical signal generated by the intensity modulated optical signal generating unit;
An optical transmission comprising: a multiplex transmitter that multiplexes and transmits the intensity-modulated optical signal from the chromatic dispersion imparting unit and the phase-modulated optical signal from the phase-modulated optical signal generator apparatus.

(Appendix 15)
An optical transmission device that relays wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
A separation unit for separating the input wavelength division multiplexed signal into a first separated wavelength multiplexed signal and a second separated wavelength multiplexed signal;
A detour sending unit that sends the first separated wavelength multiplexed signal separated by the demultiplexing unit to a detour;
A wavelength division multiplexing repeater that multiplexes and repeats the first separated wavelength multiplexed signal input through the detour and the second separated wavelength multiplexed signal from the separation unit; and
At least one of the demultiplexing unit, the detour sending unit, and the wavelength division multiplexing unit transmits one of the intensity-modulated optical signal and the phase-modulated optical signal from the first demultiplexed wavelength-multiplexed signal. With the function of selectively blocking
At least one of the demultiplexing unit, the detour sending unit, and the wavelength division multiplexing unit transmits one of the intensity-modulated optical signal and the phase-modulated optical signal from the second demultiplexed wavelength-multiplexed signal. An optical transmission device having a function of selectively blocking light.

(Appendix 16)
An optical transmission device that relays wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
For the wavelength multiplexed signal light to be input, a path switching unit that selectively switches a transmission path as a transmission destination path;
An information collection unit that collects network management information related to characteristics of transmission lines constituting a network to which the optical transmission device is applied and a modulation method of a transmission optical signal;
An optical transmission apparatus comprising: a control unit that controls a route switching setting by a route switching unit based on the management information collected by the information collecting unit.

(Appendix 17)
An optical transmission device that relays wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
A separation unit that separates an optical signal of a part of the wavelength band in the input wavelength multiplexed signal from an optical signal of another wavelength band;
A wavelength assignment changing unit for changing the wavelength assignment for the optical signals in the partial wavelength band separated by the separation unit;
An optical transmission comprising: a wavelength division multiplexing repeater that multiplexes and repeats an optical signal whose wavelength assignment has been changed by the wavelength assignment modulator and an optical signal in the other wavelength band. apparatus.

(Appendix 18)
An optical transmission device that relays wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
A wavelength arrangement conversion unit that performs wavelength arrangement conversion so as to alternately arrange wavelengths for the intensity-modulated optical signal and the phase-modulated optical signal in the input wavelength-multiplexed signal, and outputs the wavelength-multiplexed optical signal;
An interleaver demultiplexing unit that divides the wavelength-multiplexed optical signal that has undergone wavelength configuration conversion by the wavelength configuration conversion unit into two wavelength groups, each of which has a wavelength group of every other wavelength;
A bit time difference providing unit that gives a relatively different bit time difference to the two wavelength groups divided by the interleaver demultiplexing unit;
An optical transmission device comprising: an interleaver multiplexing unit that multiplexes and outputs the optical signals of the two wavelength groups from the bit time difference adding unit.

(Appendix 19)
An optical transmission device that relays wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
A separation unit that separates the intensity-modulated optical signal and the phase-modulated optical signal in the input wavelength-multiplexed signal;
An intensity difference providing unit for applying an intensity difference to the phase-modulated optical signal and the intensity-modulated optical signal separated by the separating unit;
An optical transmission device comprising: a wavelength division multiplexing relay unit that wavelength-multiplexes and relays the intensity-modulated optical signal and the phase-modulated optical signal to which the intensity difference is imparted by the intensity difference imparting unit. .

(Appendix 20)
An optical transmission method for transmitting wavelength-division multiplexed signal light of an intensity modulated optical signal and a phase modulated optical signal through a transmission line,
In order to adjust the amount of cross-phase modulation received by the phase-modulated optical signal by the intensity-modulated optical signal, for each of the intensity-modulated optical signal and the phase-modulated optical signal transmitted as the wavelength-multiplexed signal light, Give a bit time difference that is relatively different from the modulation time,
An optical transmission method comprising outputting the wavelength-multiplexed signal light including an optical signal to which the bit time difference is given.

(Appendix 21)
An optical device having an input port for inputting wavelength-multiplexed signal light and an output port, wherein the magnitude of the passage delay time from the input port to the output port is at least two steps for each wavelength channel of the wavelength-multiplexed signal light A wavelength-selectable variable delay device, characterized in that it can be set by selecting from the above settings.

(Appendix 22)
The wavelength selective variable delay device according to appendix 21, wherein the input port and the output port are common, and the reflection delay from the input port to the output port is adjusted by adjusting the angle of a reflection mirror provided inside A wavelength selective variable delay device characterized in that the time can be selected for each wavelength channel of the wavelength multiplexed signal light.

1, 1A delay block unit 2 information collection unit 3, 3A-3F, 3H control unit 4 OXC
11 demultiplexing unit 12 delay unit 12A chromatic dispersion imparting unit 13 multiplexing unit 14 optical circulator 15, 15 ', 21c to 21e, 23, 24-1, 24-2, 24c-1, 24c-2, 26-1, 26-2 Wavelength selective switch 15a, 17 Reflector 16, 22, 25-1, 25-2, 27-1, 27-2, 27a-2, 32e, 33 Delay device 21, 21a, 21b, 24a-1, 24a-2, 24b-1, 24b-2, 28-1, 28-2, 28a-2 Optical coupler 29 Dispersion compensation fiber 30 Lumped amplifier 30a, 30b Optical amplifier 31a, 32a, 32b AWG
31b, 32c, 32d Optical switch 41 Intensity modulated optical signal generator 42 Phase modulated optical signal generator 43, 43b, 43c Wavelength dispersion adder 44a-44c Multiplexer 45 Pre-equalizer 51, 52, 61, 62 Light Couplers 53 to 56, 63 to 66 Wavelength selection switch 70 Wavelength allocation conversion unit 71 Wavelength selection switch 72 Wavelength converter 73 Optical coupler 81 Interleaver demultiplexer 82 Delay unit 83 Interleaver multiplexer 91, 95 Optical amplifier 93 VOA
92 demultiplexer 94 multiplexer 100 network system 110, 110C to 110F data transfer network 111, 111-1 to 111-8, 111A, 111C to 111H, 111C-1 to 111C-8, 111D-1 to 111D-4 , 111E-1 to 111E-4, 111F-1 to 111F-4 Optical transmission device 112 Transmitter 113 Receiver 120 Control network 121 Control node 130 Management plane 140 Transmission path fiber 141 SMF
142 NZDSF
150 Optical Transmitter 160 Relay Device 210 Transmission Line Fiber 220 Centralized Amplifier

Claims (2)

An optical transmission device that relays wavelength-multiplexed signal light of an intensity-modulated optical signal and a phase-modulated optical signal through a transmission line,
A separation unit for separating the input wavelength division multiplexed signal into a first separated wavelength multiplexed signal and a second separated wavelength multiplexed signal;
A detour sending unit that sends the first separated wavelength multiplexed signal separated by the demultiplexing unit to a detour;
A wavelength division multiplexing repeater that multiplexes and repeats the first separated wavelength multiplexed signal input through the detour and the second separated wavelength multiplexed signal from the separation unit; and
At least one of the demultiplexing unit, the detour sending unit, and the wavelength division multiplexing unit transmits one of the intensity-modulated optical signal and the phase-modulated optical signal from the first demultiplexed wavelength-multiplexed signal. With the function of selectively blocking
At least one of the demultiplexing unit and the wavelength division multiplexing repeater selectively blocks transmission of either the intensity-modulated optical signal or the phase-modulated optical signal from the second demultiplexed wavelength-multiplexed signal. An optical transmission device characterized by having a function. An information collection unit that collects network management information related to characteristics of transmission lines constituting a network to which the optical transmission device is applied and a modulation method of a transmission optical signal;
Based on the management information collected by the information collection unit, a control unit for controlling a route switching setting in at least one of the separation unit, the detour transmission unit, and the wavelength division multiplexing relay unit, The optical transmission device according to claim 1, further comprising:

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