JP2011015335A - Optical communication system, optical communication method, and optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmitter which can set center wavelength spacing of each channel, setting wavelength spacing of an adjacent channel, and flexibly responding to a signal speed of each channel; an optical communication system using the same; and an optical communication method.SOLUTION: The optical communication system includes: the optical transmitter including a wavelength sweep light source 11 for outputting wavelength sweep light, a modulation signal generator 14 for generating a modulation signal obtained by subjecting transmission data of a plurality of channels to time-division multiplexing in a repetition cycle, and an optical modulator for modulating the wavelength sweep light with a modulation signal to collectively generate and transmit modulated optical signals of a plurality of wavelength channels; and an optical receiver for selecting and receiving an optical signal of a predetermined wavelength channel out of the modulated optical signals transmitted via an optical transmission path. The optical communication system is structured such that the modulation signal generator generates the modulation signal by subjecting transmission data of each channel to time-division multiplexing at timing and time length corresponding to the center wavelength and the center wavelength spacing of each wavelength channel of the modulated optical signal, and the center wavelength spacing among the respective wavelength channels is adjusted.

Description

  The present invention relates to an optical communication system, an optical communication method, and an optical transmitter that perform wavelength division multiplexing transmission of optical signals having a plurality of wavelengths generated from wavelength sweep light.

FIG. 8 shows a configuration example of an optical transmitter and an optical receiver of a conventional optical communication system (Non-Patent Document 1). FIG. 9 shows an example of a modulated signal and a modulated optical signal of a conventional optical communication system.
In FIG. 8, the wavelength sweep light source 11 of the optical transmitter 10 adjusts the signal current of the ramp waveform output from the wavelength sweep signal generator 111 to a predetermined signal amplitude by the wavelength sweep signal amplitude adjuster 112. In this configuration, a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period (1 / B) is output by applying the laser light source 113 directly to the electrode. In the wavelength sweep signal amplitude adjuster 112, for example, the AC component and the DC component are separated by a bias tee and the wavelength sweep amount is controlled by adjusting the AC component amplitude, and at the same time, the wavelength of light emitted by adjusting the DC component is adjusted. Control the band.

  In addition, for example, a distributed feedback (DFB) laser that generates a single-spectrum optical signal is used, and a method of generating a wavelength sweep light using a chirp phenomenon in which the oscillation wavelength of the laser changes according to an applied current. Good. In this configuration, a wavelength sweep range of several tens of GHz can be obtained with a repetition period of about several GHz. Also, in this case, intensity fluctuations occur simultaneously with the wavelength sweep. Therefore, if necessary, intensity fluctuation components are used by using a semiconductor optical amplifier (SOA) operated in a gain saturation region in the subsequent stage of the laser light source. (Non-Patent Document 2). Alternatively, a method of applying a wavelength sweep signal to a phase adjustment region of a distributed reflection (DBR) laser in order to generate a faster and wider wavelength sweep light may be used.

  As shown in FIG. 9, the modulation signal generator 12 generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of n channels at a timing (s1 to sn) of 1 / n of the symbol length. The optical modulator 13 modulates the wavelength sweep light input from the wavelength sweep light source 11 with the modulation signal input from the modulation signal generator 12, and modulates light having wavelengths λ1 to λn corresponding to the channels ch.1 to ch.n. Signals are collectively generated and transmitted to the optical transmission line 30.

  Here, the repetition period (1 / B) of the wavelength sweep light coincides with the symbol length of the transmission data of each channel, and the wavelength range is about the same as the product of the wavelength band of each wavelength channel and the number of wavelength channels n. It is set to become.

  The optical receiver 20 uses the optical filter 21 to extract the optical signal in the wavelength band of the desired channel, detects it with the light receiver 22, and suppresses the high-frequency component with the low-pass filter (LPF) 23, thereby obtaining the desired channel data. Reproduce. The data of the desired channel can also be reproduced by an optical receiver using coherent detection.

  Usually, in a wavelength division multiplexing (WDM) transmission system, it is necessary to prepare a light source and an optical modulator according to the number of wavelengths, and further set the wavelength of each light source to a predetermined wavelength arrangement. The transmitter configuration is complicated. On the other hand, the optical transmitter using the wavelength sweep light source shown in FIG. 8 has the feature that the configuration of the optical transmitter can be simplified because a modulated light signal of a plurality of wavelengths can be collectively generated with a single light source and an optical modulator. .

  Such an optical communication system for wavelength division multiplexing transmission includes a single star (SS) configuration in which an optical transmitter and a plurality of optical receivers shown in FIG. 10 (1) are respectively connected, and an optical branching shown in FIG. 10 (2). PON (Passive Optical Network) configuration in which an optical transmitter and a plurality of optical receivers are connected through a transmitter, and an optical transmitter and a plurality of optical receivers are connected to each wavelength through a WDM filter shown in FIG. There are connected WDM-PON configurations.

Tomohiro Taniguchi, Naoya Sakurai, Hideaki Kimura, Kiyomi Kumozaki, “Ultra High Density WDM Access System Using Shared Optical Transmitter Using Wavelength Sweep Light”, Proceedings of 2008 Society Conference of IEICE, September 2008 2nd, B-10-49, p. 192 Shinji Matsuo, Takaaki Sasuka, Toru Segawa, Naoki Fujiwara, Yasuo Shibata, Hiroshi Yasaka, Hiroyuki Suzuki, “Transmitting Elements Using Frequency Modulated SSG-DBR Lasers and Wavelength Filters”, Proceedings of the 2007 Society Conference of IEICE , The Institute of Electronics, Information and Communication Engineers August 29, 2007, C-4-14, p. 220

  Conventional optical modulators collectively generate modulated optical signals for all channels by modulating wavelength-swept light having a repetition frequency equal to the symbol rate of each channel with a modulated signal obtained by time-division multiplexing transmission data for each channel. To do. At this time, as shown in FIG. 9, the center wavelength interval of each channel is determined to be a uniform value from the relationship between the amount of wavelength sweep and the number of channels. Moreover, the wavelength of an adjacent channel is continuous and the wavelength interval of an adjacent channel is 0. Further, it was assumed that the signal speed (symbol rate) of each channel was uniform corresponding to the repetition frequency of the wavelength sweep light.

  On the other hand, when considering application to an actual system, the transmission characteristics of optical filters in optical communication systems and optical receivers are diverse, and the speeds of the optical receivers and electronic circuits of each optical receiver also vary. Can be considered. Therefore, it is desirable that the optical transmitter can flexibly cope with the center wavelength interval of each channel, the wavelength interval of adjacent channels, and the signal speed (symbol rate) of each channel in accordance with these filter characteristics and optical receiver characteristics. However, the conventional optical transmitter shown in FIG. 8 has not been configured to flexibly meet such requirements.

  The present invention relates to an optical transmitter that can flexibly cope with setting of the center wavelength interval of each channel, setting of the wavelength interval of adjacent channels, and signal speed (symbol rate) of each channel in an optical communication system using wavelength sweep light, An object of the present invention is to provide an optical communication system and an optical communication method using the optical transmitter.

  According to a first aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical communication system comprising an optical receiver that selects and receives an optical signal of a predetermined wavelength channel from among the modulated optical signals, the modulation signal generator includes a center wavelength and a center wavelength interval of each wavelength channel of the modulated optical signal. A modulation signal obtained by time-division-multiplexing transmission data of each channel is generated at a timing and time length corresponding to, and the center wavelength interval between the wavelength channels is adjusted.

  According to a second aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical communication system including an optical receiver that selects and receives an optical signal of a predetermined wavelength channel from among the modulated optical signals, the modulation signal generator combines the transmission data of each channel with a predetermined free time. In this configuration, a division-multiplexed modulation signal is generated and the wavelength interval between adjacent wavelength channels is adjusted.

  According to a third aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical communication system including an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among modulated optical signals, the modulated signal generator includes a predetermined period corresponding to a repetition period of transmission data of each channel. The optical receiver is configured to generate a modulated signal that is time-division-multiplexed repeatedly n times as n-symbol information with respect to 1 / n (n is an integer equal to or greater than 1) transmission data A configuration in which selects and receives the optical signal of the wavelength channels for transmission data is detected as information of one symbol by integrating the symbol information is repeated n times.

  The modulation signal generator of the optical communication system according to the third aspect of the invention determines the value of n for transmission data used for communication with the optical receiver according to the optical transmission line loss between the optical transmitter and the optical receiver. It is a configuration to set.

  According to a fourth aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical communication method of an optical communication system comprising an optical receiver that selects and receives an optical signal of a predetermined wavelength channel from among the modulated optical signals, the modulation signal generator is a center wavelength of each wavelength channel of the modulated optical signal A modulation signal is generated by time-division multiplexing transmission data of each channel at a timing and time length corresponding to the center wavelength interval, and the center wavelength interval between the wavelength channels is adjusted.

  According to a fifth aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical communication method of an optical communication system including an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among modulated optical signals, the modulation signal generator includes transmission data of each channel and a predetermined free time To generate a modulated signal that is time-division multiplexed and adjusts the wavelength interval between adjacent wavelength channels.

  According to a sixth aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical communication method of an optical communication system including an optical receiver that selects and receives an optical signal of a predetermined wavelength channel from among modulated optical signals, the modulation signal generator includes a repetition period of transmission data of each channel. An optical receiver that generates time-division multiplexed modulation signals n times as information of n symbols for transmission data of 1 / n (n is an integer of 1 or more) of a predetermined symbol rate corresponding to , It selects and receives the optical signal of the wavelength channels for transmission data, by integrating the symbol information is repeated n times is detected as information of one symbol.

  The modulation signal generator of the optical communication method according to the sixth aspect of the invention determines the value of n for the transmission data used for communication with the optical receiver according to the optical transmission line loss between the optical transmitter and the optical receiver. Set.

  According to a seventh aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical transmitter of an optical communication system comprising an optical receiver that selects and receives an optical signal of a predetermined wavelength channel from among the modulated optical signals, the modulation signal generator is a center wavelength of each wavelength channel of the modulated optical signal In addition, a modulation signal obtained by time-division multiplexing transmission data of each channel is generated at a timing and time length corresponding to the center wavelength interval, and the center wavelength interval between the wavelength channels is adjusted.

  According to an eighth aspect of the present invention, there is provided a wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period, and a modulation that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period. An optical transmitter including a signal generator, an optical modulator that modulates wavelength-swept light with a modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels, and the optical signal transmitted via an optical transmission line In an optical transmitter of an optical communication system comprising an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among modulated optical signals, the modulated signal generator includes transmission data of each channel and a predetermined free time. Are combined to generate a modulated signal time-division multiplexed and adjust the wavelength interval of adjacent wavelength channels.

  The first, fourth, and seventh inventions flexibly set the center wavelength interval of each channel by controlling the modulation signal input to the optical modulator by time-division multiplexing transmission data of a plurality of channels. Can do.

  In the second, fifth, and eighth inventions, the wavelength interval between adjacent channels can be flexibly set by controlling the modulation signal input to the optical modulator by time-division multiplexing transmission data of a plurality of channels. it can.

  In the third and sixth inventions, the transmission data of a plurality of channels is time-division multiplexed and the modulation signal input to the optical modulator is controlled, so that the symbol rate of each channel can be collectively or individually supported. . Also, flexible operation can be realized by making the symbol rate of each channel correspond to the optical transmission line loss between the optical transmitter and the optical receiver constituting the optical communication system.

It is a figure which shows the structural example of the optical transmitter of this invention. 3 is a diagram illustrating a configuration example of a programmable modulation signal generator 14. FIG. It is a figure which shows the example which controls the center wavelength space | interval of each channel. It is a figure which shows the example which controls the wavelength interval of an adjacent channel. It is a figure which shows the example corresponding to the symbol rate of each channel collectively. It is a figure which shows the example corresponding individually to the symbol rate of each channel. It is a figure which shows the Example of the optical communication system of this invention. It is a figure which shows the structural example of the optical transmitter and optical receiver of the conventional optical communication system. It is a figure which shows the example of the modulation signal and modulation | alteration optical signal of the conventional optical communication system. It is a figure which shows the structural example of an optical communication system.

(Configuration example of optical transmitter of the present invention)
FIG. 1 shows a configuration example of an optical transmitter according to the present invention.
In the figure, the optical transmitter 10 includes a wavelength sweep light source 11, an optical modulator 13, and a programmable modulation signal generator 14. Here, the wavelength sweep light source 11 and the optical modulator 13 have the same configuration and function as the conventional one shown in FIG.

FIG. 2 shows a configuration example of the programmable modulation signal generator 14.
In the figure, a programmable modulation signal generator 14 inputs a control signal generator 141 that outputs control signals s1 to sn, transmission data of each channel ch.1 to ch.n, and control signals s1 to sn, respectively. The circuit includes AND circuits 142-1 to 142-n that output logical product signals and an OR circuit 143 that combines the logical product signals.

  The programmable modulation signal generator 14 inputs a modulation signal generated by time-division multiplexing transmission data of each channel according to the control signals s 1 to sn to the optical modulator 13. With this signal-processed modulation signal, it is possible to flexibly cope with the center wavelength interval of each channel, the wavelength interval of adjacent channels, and the symbol rate of transmission data of each channel of the modulated optical signals of a plurality of wavelengths generated at once. .

(Example of controlling the center wavelength interval of each channel)
FIG. 3 shows an example of controlling the center wavelength interval of each channel.
Here, the wavelength band is set to 3 times channel ch.1, 2 times channel ch.2, 1 time channel ch.3, 2 times channel ch.n with respect to a predetermined reference wavelength band. An example of controlling the center wavelength interval of each channel is shown.

  The control signal generation unit 141 of the programmable modulation signal generator 14 generates control signals s1 to sn having pulse widths corresponding to the center wavelength and wavelength band assigned to each channel, and inputs them to the AND circuits 142-1 to 142-n. . The AND circuits 142-1 to 142-n extract the transmission data of each channel according to the timings and pulse widths of the control signals s1 to sn, and perform time-division multiplexed modulation as shown in FIG. Generate a signal. By modulating the wavelength sweep light with this modulated signal, modulated optical signals with different center wavelength intervals of each channel can be generated as shown in FIG.

(Example of controlling the wavelength interval between adjacent channels)
FIG. 4 shows an example of controlling the wavelength interval between adjacent channels.
The control signal generator 141 of the programmable modulation signal generator 14 generates control signals s1 to sn having a pulse width less than 1 / n at intervals of 1 / n of the symbol length (1 / B) of each channel, and AND. Input to the circuits 142-1 to 142-n. The AND circuits 142-1 to 142-n cut out the transmission data of each channel according to the timings and pulse widths of the control signals s1 to sn, and the inter-channel idle time as shown in FIG. In addition, a modulation signal that is time-division multiplexed is generated. By modulating the wavelength sweep light with this modulated signal, the wavelength of the adjacent channel becomes discontinuous as shown in FIG. 4, and a modulated optical signal having a predetermined wavelength interval can be generated.

  In addition, it is possible to set an empty time between adjacent channels as a guard band between arbitrary channels.

  Also, the control of the center wavelength interval of each channel shown in FIG. 3 and the control of the wavelength interval of adjacent channels shown in FIG. 4 can be performed together.

(Example of batch support for each channel symbol rate)
FIG. 5 shows an example of collectively corresponding to the symbol rate of each channel.
The programmable modulation signal generator 14 in FIG. 5 (1) inputs the transmission data of a plurality of channels ch.1 to ch.n, and the transmission data of each channel is 1 / n timing of the symbol length (1 / B). And time-division multiplexed to generate a modulated signal of symbol rate B [b / s / ch] for each channel. By modulating the wavelength sweep light with this modulated signal, modulated optical signals of a plurality of wavelengths are generated and output at once.

  When the symbol rate of each channel is B / 2, the programmable modulation signal generator 14 in FIG. 5 (2) generates the same modulation signal as in the case where the symbol rate is B (FIG. 5 (1)). As a result, a modulated signal is generated by time-division multiplexing each symbol of each channel twice. By modulating the wavelength sweep light with this modulated signal, modulated optical signals of a plurality of wavelengths are generated and output at once. In the optical receiver, data of the symbol rate B / 2 can be reproduced by using a low-pass filter that integrates the information of the two symbols in the subsequent stage of the light receiver.

  In the same manner, the programmable modulation signal generator responds by using the same modulation signal even when the symbol rate of each channel is B [b / s / ch] to B / K (K is an integer of 2 or more). be able to.

(Example of individually corresponding to the symbol rate of each channel)
FIG. 6 shows an example corresponding individually to the symbol rate of each channel.
Here, based on the symbol rate B [b / s] of channel ch.n, the symbol rate of channel ch.1 is B / 2 [b / s], and the symbol rate of channel ch.2 is B / 4 [b / b]. An example corresponding to the case of / s] is shown.

  The programmable modulation signal generator 14 generates a modulation signal corresponding to the symbol rate B. As a result, each symbol of channel ch.1 is repeated twice, each symbol of channel ch.2 is repeated four times, and a modulation signal time-division multiplexed at a timing of 1 / n of symbol rate B of channel ch.n is generated. Generated. By modulating the wavelength sweep light with this modulated signal, modulated optical signals of a plurality of wavelengths are generated and output at once. In an optical receiver that receives each channel, data of each symbol rate can be reproduced by using a low-pass filter that integrates information for each redundant bit.

  In this way, a modulated optical signal corresponding to the symbol rate B / m (m is an integer equal to or greater than 1) of each channel and modulated by wavelength-division multiplexed modulation signals is transmitted, and the symbol of each channel is transmitted. The data of each channel can be reproduced by reception processing corresponding to the rate (number of repetitions). When the channel symbol rate is B / m, the channel symbol information is repeated m times and time-division multiplexed, so that the optical power per symbol on the receiving side is multiplied by m. An example using this effect is shown below.

(Example of optical communication system of the present invention)
FIG. 7 shows an embodiment of the optical communication system of the present invention.
In FIG. 7, an optical branching device 41 is connected to the optical transmitter 10 via an optical transmission line 31, and optical receivers 20-1 to 20-1 are connected via a plurality of optical transmission lines 32 connected to the optical branching device 41. 20-k is connected and the next optical branching device 42 is connected, and the optical receivers 20- (k + 1) to 20-m are connected via the plurality of optical transmission lines 33 connected to the optical branching device 42. The optical receivers 20- (m + 1) to 20-n are connected through a plurality of optical transmission lines 34 that are connected and have a propagation distance longer than that of the optical transmission line 33.

  The optical signal transmitted from the optical transmitter 10 is received by each optical receiver 20 with an increase in optical transmission line loss whenever the transmission distance is further increased each time the optical branching units 41 and 42 repeat the branching. .

  Therefore, the symbol rates of B [b / s] are assigned to the channels λ1 to λk. Further, the optical receiver 20- (k + 1) having a relatively large optical transmission line loss connected via the optical branching unit 31, the optical branching unit 41, the optical transmission line 32, the optical branching unit 42, and the optical transmission line 33. ˜20−m are assigned channels in the wavelength bands λk + 1 to λm whose symbol rate is set to B / K [b / s]. Further, the optical receiver 20- (m + 1) to which the optical transmission line loss is further increased through the optical branching unit 31, the optical branching unit 41, the optical transmission line 32, the optical branching unit 42, and the optical transmission line 34. Channels in the wavelength bands λm + 1 to λn whose symbol rate is set to B / M [b / s] (K <M) are assigned to 20-n.

  As described above, the remote optical receivers 20- (k + 1) to 20-m and 20- (m + 1) to 20-n where the optical transmission line loss from the optical transmitter 10 becomes large have symbols. Optical reception that can be accommodated by the optical transmitter 10 by assigning wavelength bands λk + 1 to λm and λm + 1 to λn whose rates are set to B / K [b / s] or B / M [b / s] The range of the vessel can be expanded. On the other hand, the wavelength bands λ1 to λk whose symbol rate is set to B [b / s] are assigned to the nearby optical receivers 20-1 to 20-k where the optical transmission line loss from the optical transmitter 10 is small. Thus, high-speed data transmission can be realized.

  In each of the embodiments described above, for example, when the optical receiver corresponding to channel ch.i is not connected, control of channel ch.i generated by the control signal generator 141 of the programmable modulation signal generator 14 is performed. This can be dealt with by setting the signal si to "0". When an optical receiver corresponding to the channel ch.i is connected, a logical product of the control signal si of the channel ch.i with “1” and the transmission data may be obtained.

DESCRIPTION OF SYMBOLS 10 Optical transmitter 11 Wavelength sweep light source 111 Wavelength sweep signal generator 112 Wavelength sweep signal amplitude adjuster 113 Laser light source 12 Modulation signal generator 13 Optical modulator 14 Programmable modulation signal generator 141 Control signal generator 142 AND circuit 143 OR circuit 20 Optical receiver 21 Optical filter 22 Light receiver 23 Low-pass filter (LPF)
30, 31, 32, 33, 34 Optical transmission line 41, 42 Optical splitter

Claims (10)

A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulated signal and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical communication system comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulation signal generator generates a modulation signal obtained by time-division multiplexing transmission data of each channel at a timing and a time length corresponding to a center wavelength and a center wavelength interval of each wavelength channel of the modulated optical signal, An optical communication system, characterized in that a center wavelength interval between wavelength channels is adjusted. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical communication system comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulation signal generator is configured to generate a modulation signal that is time-division multiplexed by combining transmission data of each channel and a predetermined idle time, and adjusts the wavelength interval between adjacent wavelength channels. system. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical communication system comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulation signal generator generates n symbol information for transmission data of 1 / n (n is an integer of 1 or more) of a predetermined symbol rate corresponding to the repetition period among transmission data of each channel. It is a configuration that generates a modulation signal that is time-division multiplexed by repeating n times,
The optical receiver is configured to select and receive an optical signal of a wavelength channel for the transmission data, integrate the symbol information repeated n times, and detect as information of one symbol. . The optical communication system according to claim 3.
The modulation signal generator sets the value of n for the transmission data used for communication with the optical receiver according to an optical transmission line loss between the optical transmitter and the optical receiver. There is an optical communication system characterized by that. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulated signal and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical communication method of an optical communication system, comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulation signal generator generates a modulation signal obtained by time-division multiplexing transmission data of each channel at a timing and a time length corresponding to a center wavelength and a center wavelength interval of each wavelength channel of the modulated optical signal, An optical communication method characterized by adjusting a central wavelength interval between wavelength channels. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical communication method of an optical communication system, comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulation signal generator generates a modulation signal that is time-division multiplexed by combining transmission data of each channel and a predetermined idle time, and adjusts the wavelength interval between adjacent wavelength channels. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical communication method of an optical communication system, comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted via an optical transmission line;
The modulation signal generator generates n symbol information for transmission data of 1 / n (n is an integer of 1 or more) of a predetermined symbol rate corresponding to the repetition period among transmission data of each channel. Generate a time-division multiplexed modulated signal repeated n times,
The optical receiver selects and receives an optical signal of a wavelength channel for the transmission data, integrates the symbol information repeated n times, and detects it as information of one symbol. The optical communication method according to claim 7.
The modulation signal generator sets the value of n for the transmission data used for communication with the optical receiver according to an optical transmission line loss between the optical transmitter and the optical receiver. An optical communication method. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical transmitter of an optical communication system comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulation signal generator generates a modulation signal obtained by time-division multiplexing transmission data of each channel at a timing and a time length corresponding to a center wavelength and a center wavelength interval of each wavelength channel of the modulated optical signal, An optical transmitter characterized in that the center wavelength interval between wavelength channels is adjusted. A wavelength sweep light source that outputs a wavelength sweep light that sweeps a predetermined wavelength range at a predetermined repetition period; a modulation signal generator that generates a modulation signal obtained by time-division multiplexing transmission data of a plurality of channels within the repetition period; An optical transmitter including an optical modulator that modulates the wavelength sweep light with the modulation signal, and generates and transmits modulated optical signals of a plurality of wavelength channels at once;
In an optical transmitter of an optical communication system comprising: an optical receiver that selects and receives an optical signal of a predetermined wavelength channel among the modulated optical signals transmitted through an optical transmission line;
The modulated signal generator is configured to generate a modulated signal that is time-division multiplexed by combining the transmission data of each channel and a predetermined idle time, and adjusts the wavelength interval between adjacent wavelength channels. vessel.

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