JP2008085585A - Optical element integrated module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dispense with an optoelectrical conversion device by using a mutual absorption modulation effect, and also to dispense with an electric circuit for a high frequency. <P>SOLUTION: An optical element integrated module includes: a branch 20; a modulation part 30; an input optical multiplexing part 25; a multiplexing part 50; and a delay part 40. The branch branches an optical clock signal with a period T into first to 2<SP>n</SP>-th clock signals (n is an integer not less than 1). The modulation part includes the first to 2<SP>n</SP>-th modulators. The k-th modulator (k is an integer not less than 1 and not more than 2<SP>n</SP>) generates the k-th optical modulation signal by the mutual absorption modulation effect between the k-th clock signal and the k-th optical data signal. The input optical multiplexing part includes the first to 2<SP>n</SP>-th input optical multiplexers. The k-th input optical multiplexer transmits the k-th optical data signal and the k-th clock signal to the k-th modulator. The multiplexing part multiplexes the first to 2<SP>n</SP>-th optical modulation signals generated in the modulation part so as to generate an optical time-division multiplex signal. The delay part gives a time difference T/2<SP>n</SP>between the successive optical modulation signals of the first to 2<SP>n</SP>-th optical modulation signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element integrated module formed by integrating optical passive elements such as an optical branching device and optical active elements such as an optical modulator, and in particular multiplexes optical pulse signals in optical time division multiplexing communication. The present invention relates to an integrated optical device module.

  In recent years, communication demand has been rapidly increasing due to the spread of the Internet and the like. Correspondingly, high-speed and large-capacity optical communication networks configured by connecting optical processing nodes with optical fibers are being developed. The optical processing node used in this optical communication network converts an optical signal received from the connected optical fiber into an electrical signal by photoelectric conversion, performs signal processing with the electrical signal, The optical signal is converted into an optical signal by optical conversion and sent to an optical fiber.

With reference to FIG. 8, an optical time division multiplexing (OTDM) module used in the optical processing node will be described. The OTDM module 110 includes four electro-absorption semiconductor optical modulators (EAMs) 130a to 130d. The optical clock signal input from the optical clock signal input terminal 161 is branched into four by the three half mirrors 121, 122a and 122b and then sent to the EAMs 130a to 130d, respectively. Each EAM 130a to 130d modulates an optical clock signal with a data signal that is an electrical signal to generate an optical modulation signal. The optical modulation signals generated by the EAMs 130a to 130d are given a predetermined delay by the delay units 140a to 140c and then multiplexed by the three half mirrors 152a, 152b and 152c. An OTDM signal obtained as a result of multiplexing is output from the output terminal 165 (see, for example, Patent Document 1 and Non-Patent Document 1).
JP 2005-26725 A 160 Gbit / s ultra-fast optical time division multiplexing / separation technology using EAM ”, Hitoshi Murai, O Plus E, May 2005, Vol. 27 NO. 5, pp. 535-540

  However, when optical time division multiplexing of four optical data signals input to an optical processing node is performed using the OTDM module described in Patent Document 1 or Non-Patent Document 1, the optical clock signal is modulated with an electrical signal. There is a need to. For this reason, an optical-electrical conversion device for once converting an optical data signal into an electrical signal is required. Further, since the frequency of the electric signal input to the EAM is high for an optical data signal having a high data rate, a high frequency electric circuit for inputting the high frequency electric signal to the EAM is required.

  Thus, the inventors of the present application conducted extensive research and found that the cross-absorption modulation effect (XAM) can be used in the OTDM module (for example, IEEE PTL, Vol. 17, No. 9, September (2005)). ). According to the mutual absorption modulation effect, when a bias voltage is applied to the saturable absorber, the saturable absorber serves as a light absorber while the light input to the region to which the bias voltage is applied is weak. When the light intensity increases, it becomes transparent because it cannot absorb any more light. In other words, when the optical signal in the ON state is input simultaneously with the optical clock signal, the optical clock signal passes through the saturable absorber, and when the optical signal is not input, the optical clock signal is absorbed. become.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to make use of XAM, which eliminates the need for an optical-electrical converter and eliminates the need for a high-frequency electric circuit. The object is to provide an element integrated module.

In order to achieve the above-described object, an optical element integrated module according to the present invention includes a branching unit, a modulating unit, an input multiplexing unit, a multiplexing unit, and a delay unit. The branching unit branches an optical clock signal having a period T into first to ²ⁿ clock signals (n is an integer of 1 or more).

The modulation unit generates the first to ²ⁿ optical modulation signals by applying intensity modulation to each of the first to ²ⁿ clock signals. The input multiplexing unit sends the first to ²ⁿ optical data signals to the modulation unit.

The multiplexing unit combines the first to ²ⁿ optical modulation signals generated by the modulation unit to generate an optical time division multiplexed signal. The delay unit gives a time difference of T / ²ⁿ between the sequential optical modulation signals of the first to ²ⁿ optical modulation signals.

Here, the modulation unit includes first to ²ⁿ modulators. A kth modulator (k is an integer of 1 to ²ⁿ ) generates a kth optical modulation signal by a mutual absorption modulation effect between the kth clock signal and the kth optical data signal. In addition, the input multiplexing unit includes first to ²ⁿ input multiplexers, and the kth input multiplexer combines the kth optical data signal and the kth clock signal. To the kth modulator.

According to a preferred embodiment of the optical element integrated module of the present invention, each of the first to ²ⁿ input multiplexers may be constituted by a half mirror.

  The kth input multiplexer composed of a half mirror reflects the kth optical data signal and sends it to the kth modulator, and transmits the kth clock signal to the kth modulator. send.

In the implementation of the above-described optical element integrated module, preferably, the optical axes of the first to ²ⁿ modulators are provided in the same reference plane, and the first to ²ⁿ optical data signals are respectively in the reference plane. It is preferable that the first to ²ⁿ optical data signal input terminals provided on the input multiplexer are input to the input multiplexer.

Further, in the implementation of the above-described optical element integrated module, the first to ²ⁿ optical data signals are respectively input from the first to ²ⁿ optical data signal input terminals provided at right angles to the reference plane. It may be configured to be input to

According to another preferred embodiment of the optical element integrated module of the present invention, the optical axes of the first to ²ⁿ modulators are provided in the same reference plane, and the first to ²ⁿ input axes are combined. The wave filter may be composed of a band-pass filter having a natural boundary wavelength λ _th0 of reflection and transmission with respect to light incident along the optical axis.

The optical axis of the 1st to ²ⁿ input multiplexers is inclined at an angle θ with respect to the reference plane, and the light propagates in the reference plane of the bandpass filter constituting the 1st to ²ⁿ input multiplexers. The boundary wavelength λ _th (= λ _th0 / cos θ) of reflection and transmission with respect to is a value between the wavelength λ _cl of the optical clock signal and the wavelength λ _d of the optical data signal. The 1st to ²ⁿ optical data signals are input to the input multiplexing unit from the 1st to ²ⁿ optical data signal input terminals provided at an angle of 2 × θ with respect to the reference plane.

  According to the optical element integrated module of the present invention, since the optical clock signal is modulated with the optical data signal by utilizing the mutual absorption modulation effect (XAM), the optical-electrical conversion device becomes unnecessary. In addition, a bias voltage is only applied to a modulator that performs intensity modulation by the mutual absorption modulation effect, and no high-frequency electrical signal is input. Therefore, a high frequency electric circuit is not required.

  Further, by configuring the optical element integrated module with a spatial coupling system, it is possible to easily adjust the phase of the carrier wave as in the conventional spatial coupling system optical element module.

  Furthermore, when the optical multiplexer is configured with a half mirror and the optical data signal is incident from a direction perpendicular to the reference plane, that is, from the upper surface or the lower surface of the optical element module, the number of multiplexing increases. Even if it exists, it can be made compact without enlarging the size of an optical element module.

  Further, when the optical multiplexer is configured using a band filter and the reflection and transmission characteristics of the band filter are used, the optical loss in the optical multiplexer can be reduced as compared with the case of using a half mirror. Therefore, the amplification factor for the optical data signal, the optical clock signal, the time division multiplexed optical signal, etc. can be kept low, leading to low power consumption.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the positions, sizes, and arrangement relationships of the constituent elements are merely schematically shown to the extent that the present invention can be understood. In the following, a preferred configuration example of the present invention will be described. However, numerical conditions and the like are merely preferred examples. Therefore, the present invention is not limited to the following embodiment.

(Optical device integrated module)
The optical element integrated module of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram for explaining signal processing in an optical element integrated module. Here, an optical time division multiplex (OTDM) module will be described as an example of the optical element integrated module. FIG. 2 is a timing chart of signal processing. In FIG. 2, the horizontal axis indicates time, and the vertical axis indicates light intensity.

  The optical element integrated module (OTDM module) 10 includes a branching unit 20, an input multiplexing unit 25, a modulation unit 30, a delay unit 40, and a multiplexing unit 50.

First to ²ⁿ optical data signals (indicated by arrows S111-1 to ²ⁿ in the figure) are input to the optical element integrated module 10 from the outside in parallel. Here, n is an integer of 1 or more.

An optical clock signal S101 having a period T [s] input from the outside to the optical element integrated module 10 is output from the first to ²ⁿ clock signals (indicated by arrows S103-1 to ²ⁿ in the drawing) at the branching unit 20. And then sent to the input multiplexer 25.

The input multiplexer 25 multiplexes the 1st to ²ⁿ clock signals S103-1 to ²ⁿ and the 1st to ²ⁿ optical data signals (indicated by arrows S111-1 to ²ⁿ in the figure). To the modulation unit 30. The input multiplexer 25 includes first to ²ⁿ input multiplexers 26-1 to ²ⁿ . The first to ²ⁿ input multiplexers 26-1 to ²ⁿ are input with the above-described first to ²ⁿ optical data signals S111-1 to ²ⁿ in a one-to-one relationship. The branched first to ²ⁿ clock signals S103-1 to ²ⁿ are also input to the first to ²ⁿ input multiplexers 26-1 to ²ⁿ in a one-to-one relationship.

Therefore, the first input multiplexer 26-1 sends the first clock signal S103-1 and the first optical data signal S111-1 to the modulation unit 30. Similarly, the k-th input multiplexer 26-k multiplexes the k-th clock signal S103-k and the k-th optical data signal S111-k and sends them to the modulation unit 30. Here, k is an integer of 1 to ²ⁿ .

Here, the frequency of the clock signal S101, the data rate of the optical data signal S111-1～2 ⁿ of the 1 to 2 ⁿ is set to match. For example, when the data rate of the optical data signal S111-1～2 ⁿ of the 1 to 2 ⁿ is 10 [Gbit / s], the frequency of the clock signal S101 is set to 10 [GHz]. Further, the clock signal S101, and the optical data signal S111-1～2 ⁿ of the 1 to 2 ^n, synchronously input to the input multiplexer 26-1～2 ⁿ of the 1 to 2 ^n.

The modulation unit 30 includes first to ²ⁿ modulators 31-1 to ²ⁿ . The modulation unit 30 applies intensity modulation to each of the first to ²ⁿ clock signals to generate an optical modulation signal S107. Generate. The k-th modulator 31-k modulates the intensity of the k-th optical clock signal S103-k by the already described mutual absorption modulation effect (XAM), and generates an optical modulation signal (indicated by an arrow S107-k in the figure). .) Is generated. The 1st to ²ⁿ modulators 31-1 to ²ⁿ are composed of components including a saturable absorber such as an electroabsorption semiconductor optical modulator (EAM). Modulator 31-1～2 ⁿ of the 1 to 2 ⁿ are connected in a one-to-one relationship to the input multiplexer 26-1～2 ⁿ of the 1 to 2 ^n.

  For example, in a state where a bias voltage of −1.2 V is applied to the saturable absorber, when the input optical data signal is in an ON state, that is, when the data indicated by the optical data signal is “1”, the saturable absorber is further increased. Is in a state where it cannot absorb light, that is, in a transparent state. On the other hand, when the input optical data signal is in an off state, that is, when the data indicated by the optical data signal is “0”, the incident light is absorbed, that is, in an opaque state.

  The optical clock signal S103 input together with the optical data signal S111 passes through the modulator 31 when the saturable absorber is in a transparent state, and does not pass through the modulator 31 when the saturable absorber is in an opaque state. As a result, the modulator 31 can generate an optical modulation signal S107 that is an optical pulse signal by intensity-modulating the optical clock signal S103 according to the on state or the off state of the optical data signal S111.

  Here, the expression “optical pulse signal” is used only when it means an optical pulse train reflecting a binary digital signal indicating transmission data obtained by optical modulation of the optical pulse train. On the other hand, the expression “optical pulse train” is used to indicate an optical pulse train in which optical pulses are arranged at regular intervals.

The 1st to ²ⁿ clock signals S103-1 to ²ⁿ branched by the branching unit 20 propagate through the optical paths of the same length, respectively, and simultaneously to the 1st to ²ⁿ modulators 31-1 to ²ⁿ . Entered. Further, the optical modulation signal S107-1～2 ⁿ of the 1 to 2 ⁿ generated by the modulator 31-1～2 ⁿ of the 1 to 2 ⁿ propagates the optical path of the same length, respectively, the delay unit 40. Therefore, the time difference between the optical modulation signal S107-1～2 ⁿ of the 1 to 2 ⁿ is input to the delay unit 40 is not, i.e. are synchronized.

Delay unit 40, between the successive optical modulation signal of the optical modulation signal S107-1～2 ⁿ of the 1 to 2 ^n, by changing the optical path length, giving a time difference of T ^{/ 2} n [s], respectively. The optical modulation signals (denoted by arrows S109-1 to ²ⁿ in the figure) each given a predetermined delay by the delay unit 40 are sent to the multiplexing unit 50.

  Although the example in which the delay unit 40 is provided between the modulation unit 30 and the multiplexing unit 50 has been described here, the present invention is not limited to this example. The optical clock signal S103 and the optical data signal S111 input to the modulation unit 30 only need to be synchronized. For example, a delay unit 40 is provided between the input multiplexing unit 25 and the modulation unit 30, and the optical clock signal S103 and The optical data signal S111 may be modulated after giving a predetermined delay.

The multiplexing unit 50 multiplexes the delayed first to ²ⁿ optical modulation signals S109-1 to ²ⁿ to generate an optical time division multiplexed signal (indicated by an arrow S115 in the figure).

  Here, when n is 2, a 10 GHz RZ (Return to Zero) optical signal is input as the optical clock signal S101 (FIG. 2A), and the optical data signal S111 is 10 [Gbit / s]. When an NRZ (Non-Return to Zero) optical signal is input (FIG. 2B), a 40 [Gbit / s] RZ optical signal can be generated as an OTDM signal. Here, it is assumed that the first to fourth optical data signals S111-1 to S111-1 are NRZ optical signals and the transmission data is “1, 1, 1, 0, 1, 1”.

  The optical modulation signal S107 obtained by XAM becomes an optical pulse signal reflecting a binary digital signal that is transmission data (FIG. 2C).

  The first optical modulation signal S107-1 is sent to the multiplexing unit 50 without receiving a predetermined delay by the delay unit 40. The second optical modulation signal S107-2 is sent to the multiplexing unit 50 after being delayed by T / 4 [s] with respect to the first optical modulation signal S107-1 by the delay unit 40 (FIG. 2 ( D)). The third optical modulation signal S107-3 is sent to the multiplexing unit 50 after being delayed by T / 2 [s] with respect to the first optical modulation signal S107-1 by the delay unit 40 (FIG. 2 ( E)). The fourth optical modulation signal S107-4 is sent to the multiplexing unit 50 after being delayed by 3T / 4 [s] with respect to the first optical modulation signal S107-1 by the delay unit 40 (FIG. 2 ( F)). As a result, a time difference of T / 4 [s] is given between the sequential optical modulation signals of the first to fourth optical modulation signals S107-1 to S107-1.

  When these first to fourth optical modulation signals S109-1 to S109-1 are multiplexed by the multiplexing unit 50, four multiplexed 40 [Gbit / s] RZ optical signals can be generated (FIG. 2 ( G)).

  Although an example in which an NRZ optical signal is input as an optical data signal has been described here, an RZ optical signal may be input.

The signal output from the optical element integrated module includes other period components such as 10 [Gbit / s] in addition to 40 [Gbit / s] OTDM signal. It is good to remove at 80. The OTDM signal that has passed through the bandpass filter 80 can be amplified by the optical amplifier 75 as necessary. Further, the optical data signals S111-1 to ²ⁿ supplied to the input multiplexing unit 25 are necessary for making the modulator 26 transparent when each of the optical data signals S111-1 to ²ⁿ is in an on state. In order to amplify the intensity, an optical amplifier 70-1 to ²ⁿ may be provided for each optical data signal.

Here, as the band-pass filter 80 and the optical amplifiers 70-1 to 2 ⁿ and 75, any suitable conventionally known ones can be used. For example, as the optical amplifiers 70-1 to ²ⁿ and 75, erbium-doped fiber amplifiers (EDFA) can be used.

In FIG. 1, the configuration example in which the band pass filter 80 and the optical amplifiers 70-1 to 2 ⁿ and 75 are provided outside the OTDM module is shown, but these may be provided in the OTDM module.

  According to the optical element integrated module of the present invention, since the optical clock signal is modulated with the optical data signal by using XAM, the conventionally required optical-electrical conversion device is not required. Further, only a bias voltage is applied to the EAM, and no high frequency electrical signal is input. Therefore, a high frequency electric circuit is not required.

  Further, since the optical element integrated module is configured by a spatial coupling system, the phase of the carrier wave can be easily adjusted as in the conventional spatial coupling optical element module.

(First embodiment)
With reference to FIG. 3, the optical element integrated module of 1st Embodiment is demonstrated.

  FIG. 3 is a schematic configuration diagram of the optical element integrated module according to the first embodiment. Here, an example where n is 1, that is, a 2-multiplex OTDM module will be described, but n is not limited to 1 and may be an integer of 2 or more.

  In the optical element integrated module (OTDM module) of the first embodiment, the branching unit is composed of one branching device 21. The input multiplexer is composed of a first input multiplexer 26-1 and a second input multiplexer 26-2, and the modulator is composed of the first modulator 31-1 and the second input multiplexer 26-1. It consists of a modulator 31-2. Further, each of the delay unit and the multiplexing unit includes one delay device 41 and one multiplexer 51.

  The OTDM module includes a branching device 21, a first input multiplexer 26-1, a second input multiplexer 26-2, a first modulator 31-1, a first modulator 31-1, and a second modulator 31-1. The optical components of the second modulator 31-2, the delay device 41, and the multiplexer 51 are provided. Here, it is preferable that the support 5 has a structure in which, for example, the bottom plate 7 is formed in a hexagonal box shape, and an optical component can be detachably accommodated from the outside. In this configuration example, the bottom plate 7 of the support 5 is a surface plate, and a plane parallel to the surface plate is a reference plane.

  The optical axis of each optical component is provided in the reference plane, and each optical signal propagating in the OTDM module propagates in the optical path in the reference plane.

  The OTDM module may include an optical path changer for changing the optical path of light propagating in the OTDM module in addition to the above-described optical components.

  3 includes a first input-side optical path changer 35-1 between the first input multiplexer 26-1 and the first modulator 31-1, and the second input multiplexer 26. -2 and the second modulator 31-2, a second input side optical path changer 35-2 is provided between the first modulator 31-1 and the multiplexer 51. In the example, an output side optical path changer 37-1 is provided, and a second output side optical path changer 37-2 is provided between the delay unit 41 and the multiplexer 51.

  The support 5 of the OTDM module has an optical clock signal input terminal 61, a first optical data signal input terminal 62-1 and a second optical data signal input terminal 62-2, and an optical modulation signal output terminal 65. Is provided. The optical clock signal input terminal 61 introduces the optical clock signal S101 in the reference plane, and the first optical data signal input terminal 62-1 and the second optical data signal input terminal 62-2 are respectively in the reference plane. The first optical data signal S111-1 and the second optical data signal S111-2 are introduced. This optical element integrated module is a so-called spatially coupled module in which an optical signal propagates through a space between required optical components.

  In order to realize spatial coupling between optical components, each optical component includes a lens at one or both of an input end and an output end, but description and illustration of the lens are omitted.

  Here, as the branching unit 21, the first input multiplexer 26-1, the second input multiplexer 26-2, and the multiplexer 51, for example, a conventionally known half mirror can be used. As the delay device 41, any suitable conventionally known delay adjuster can be used. For example, as described in Patent Document 1, it is possible to adjust the optical path by combining two parallel flat glasses and tilting the parallel flat glasses with respect to the light propagation optical path. As the input-side optical path changer 35 and the output-side optical path changer 37, any suitable conventionally known total reflection mirror can be used.

  The optical clock signal S101 is bifurcated into a first clock signal S103-1 and a second clock signal S103-2 by the branching device 21. One of the two branched first clock signals S103-1 is sent to the first input multiplexer 26-1. Also, the other second clock signal S103-2 that has been bifurcated is sent to the second input multiplexer 26-2.

  The first optical data signal S111-1 input to the optical element integrated module via the first optical data signal input terminal 62-1 is sent to the first input multiplexer 26-1. In this embodiment, the first input multiplexer 26-1 is formed of a half mirror, and the component of the first clock signal S103-1 that is transmitted through the first input multiplexer 26-1 is After the optical path is changed by the first input side optical path changer 35-1, it is sent to the first modulator 31-1. In addition, after the component of the first optical data signal S111-1 reflected by the first input multiplexer 26-1 is changed in the optical path by the first input side optical path changer 35-1, It is sent to the first modulator 31-1.

  The second optical data signal S111-2 input to the optical element integrated module via the second optical data signal input terminal 62-2 is sent to the second input multiplexer 26-2. In this embodiment, the second input multiplexer 26-2 is formed of a half mirror, and the component of the second clock signal S103-2 that passes through the second input multiplexer 26-2 is After the optical path is changed by the second input-side optical path changer 35-2, it is sent to the second modulator 31-2. In addition, after the component of the second optical data signal S111-2 reflected by the second input multiplexer 26-2 is changed by the second input side optical path changer 35-2, It is sent to the second modulator 31-2.

  In the first modulator 31-1, the first optical modulation signal S107-1 is generated by mutual absorption intensity modulation (XAM) between the first optical clock signal S103-1 and the first optical data signal S111-1. Generated. In the second modulator 31-2, the second optical modulation signal S107-2 is generated by XAM of the second optical clock signal S103-2 and the second optical data signal S111-2.

  The first optical modulation signal S107-1 is sent to the multiplexer 51 after the optical path is changed by the first output side optical path changer 37-1 without receiving a predetermined delay by the delayer. On the other hand, the second optical modulation signal S107-2 is delayed by T / 2 [s] with respect to the first optical modulation signal S107-1 by the delay unit 41, and then the second output side optical path changer. At 37-2, the optical path is changed and then sent to the multiplexer 51.

  The multiplexer 51 multiplexes the first optical modulation signal S107-1 and the second optical modulation signal S107-2 to generate and output a doubled optical time division multiplexed signal S115.

  Here, an example in which the optical clock signal and the optical data signal are input to the modulator from the same direction has been described. However, the optical clock signal and the optical data signal may be input in synchronization, and the traveling direction thereof is not limited. Absent. That is, the optical clock signal and the optical data signal may be input to the modulator from different directions.

  In this case, the functions of the optical clock signal input terminal and the output terminal in the configuration example described with reference to FIG. 3 are switched, the optical clock signal is input from the output terminal, and the multiplexed signal is extracted from the optical clock signal input terminal. Can do.

  With reference to FIG. 4, a configuration example in which the optical clock signal and the optical data signal are input from different directions will be described. FIG. 4 is a schematic diagram of another configuration example of the OTDM module according to the first embodiment.

  An optical clock signal (indicated by an arrow S102 in the figure) input from the optical modulation signal output terminal 65 is sent to the first clock signal (indicated by an arrow S104-1 in the figure) and the second by the multiplexer 51. Two branches to a clock signal (indicated by an arrow S104-2 in the figure). One of the two branched first clock signals S104-1 is sent to the first modulator 31-1. Also, the other second clock signal S104-2 that has been branched in two is sent to the second modulator 31-2 after being delayed by the delay unit 41 by T / 2 [s].

  The first optical data signal S111-1 input to the optical element integrated module via the first optical data signal input terminal 62-1 is sent to the first input multiplexer 26-1. In this embodiment, since the first input multiplexer 26-1 is composed of a half mirror, it is reflected by the first input multiplexer 26-1 in the first optical data signal S111-1. The component is sent to the first modulator 31-1 after the optical path is changed by the first input side optical path changer 35-1.

  The second optical data signal S111-2 input to the optical element integrated module via the second optical data signal input terminal 62-2 is sent to the second input multiplexer 26-2. In this embodiment, the second input multiplexer 26-2 is formed of a half mirror, and the component reflected by the second input multiplexer 26-2 is included in the second optical data signal S111-2. After the optical path is changed by the second input side optical path changer 35-2, the optical signal is sent to the second modulator 31-2.

  In the first modulator 31-1, the first optical modulation signal (indicated by an arrow S108-1 in the figure) is obtained by XAM of the first optical clock signal S104-1 and the first optical data signal S111-1. .) Is generated. Further, in the second modulator 31-2, the second optical modulation signal (in the figure, the arrow S108-2) is obtained by XAM of the second optical clock signal S104-2 and the second optical data signal S111-2. Is generated).

  In the first optical modulation signal S108-1, after the optical path is changed by the first input side optical path changer 35-1, a component that passes through the first input multiplexer 26-1 is transmitted to the branching unit 21. Sent. On the other hand, the component of the second optical modulation signal S108-2 transmitted through the second input multiplexer 26-2 after the optical path is changed by the second input side optical path changer 35-2 is a branching device. 21.

  The branching device 21 multiplexes the first optical modulation signal S108-1 and the second optical modulation signal S108-2 to generate a doubled optical time division multiplexed signal (indicated by an arrow S116 in the figure). Then, the signal is output through the optical clock signal input terminal 61.

  Note that the optical element integrated module having the same function as that of the OTDM module shown in FIG. 3 can be realized by a so-called fiber coupling type module configured by using an optical fiber and an optical coupler.

  The fiber coupled module will be described with reference to FIG. In the fiber coupling type module, the branching unit 28, the first input multiplexer 29-1, the second input multiplexer 29-2, and the multiplexer 58 may be formed of any suitable conventionally known optical coupler. it can. Further, the optical components are coupled by optical fibers.

  The optical clock signal S101 is branched into two by the branching device 28, one first clock signal S103-1 is sent to the first input multiplexer 29-1, and the other second clock signal S103-2 is sent. It is sent to the second input multiplexer 29-2. The first optical data signal S111-1 is further input to the first input multiplexer 29-1. The first clock signal S103-1 and the first optical data signal S111-1 are combined by the first input multiplexer 29-1, and then sent to the first modulator 32-1. The second optical data signal S111-2 is further input to the second input multiplexer 29-2. The second clock signal S103-2 and the second optical data signal S111-2 are combined by the second input multiplexer 29-2 and then sent to the second modulator 32-2.

  The modulation by the first modulator 32-1 and the second modulator 32-2 is performed similarly to the first embodiment described with reference to FIG. The first optical modulation signal S107-1 modulated by the first modulator 32-1 is sent to the multiplexer 58. The second optical modulation signal S107-2 modulated by the second modulator 32-2 is sent to the multiplexer 58 after being delayed by T / 2 [s] by the delay unit. The multiplexer 58 multiplexes the first optical modulation signal S107-1 and the second optical modulation signal S107-2 and outputs the result as an optical time division multiplexed signal S115.

  Here, when an optical clock signal having a period T of 10 [GHz] is input into the optical fiber, the optical pulses are arranged approximately every 2 cm in the optical fiber. In order to make the delay amount uniform in order to perform optical time division multiplexing, it is necessary to fuse optical fibers with an accuracy of mm. Further, in the configuration using the optical fiber, it is very difficult to adjust the phase of the carrier wave of 0.1 μm or less.

  On the other hand, in the spatially coupled optical element integrated module, the adjustment can be performed by the phase level of the carrier wave as in the known OTDM module.

(Second Embodiment)
With reference to FIG. 6, the optical element integrated module of 2nd Embodiment is demonstrated.

  6A and 6B are schematic configuration diagrams of the optical element integrated module of the second embodiment. FIG. 6A is a plan view of the optical element integrated module of the second embodiment. FIG. 6B is a side view of the optical element integrated module according to the second embodiment, and particularly shows an enlarged view of the input multiplexer and the optical data signal input terminal.

  Here, an example where n is 2, that is, a 4-multiplex OTDM module will be described. Note that n is not limited to 2, and may be 1 or an integer of 3 or more.

  In the first embodiment, n is 1, and the optical data signal is input so as to propagate through the reference plane. On the other hand, in the second embodiment, n is 2, and the optical data signal is input at a right angle to the reference plane. Since the configuration other than this is the same between the first embodiment and the second embodiment, a duplicate description may be omitted.

  In the OTDM module of the second embodiment, the branching unit includes first to third branching units 22-1 to 23-1. Further, the input multiplexer is composed of first to fourth input multiplexers 26-1 to 26-4, and the modulator is composed of first to fourth modulators 31-1 to 31-4. Further, the delay unit includes first to third delay units 42-1 to 42-1, and the multiplexing unit includes first to third multiplexers 52-1 to 52-1.

  The OTDM module includes first to third branching units 22-1 to 23-1, first to fourth input multiplexers 26-1 to 26-4, and first to fourth modulators 31 on the bottom plate 8 of the support 6. Optical components of -1 to 4, first to third delay devices, and first to third multiplexers 52-1 to 52-3 are provided. Here, it is preferable that the support 6 has a structure in which, for example, the bottom plate 8 is formed in a hexagonal box shape, and an optical component can be detachably accommodated from the outside. In this configuration example, the bottom plate 8 of the support 6 is used as a surface plate, and a plane parallel to the surface plate is used as a reference plane.

  The OTDM module may include an optical path changer for changing the optical path of light propagating in the OTDM module in addition to the above-described optical components.

  FIG. 6 shows an example including first to fourth input-side optical path changers 35-1 to 35-4 and first to fourth output-side optical path changers 37-1 to 37-4. A first input-side optical path changer 35-1 is provided between the second branching device 22-2 and the first input multiplexer 26-1, and the third branching device 22-3 and the second input branching device 26-1. A second input side optical path changer 35-2 is provided between the input multiplexer 26-2, and between the second branching device 22-2 and the third input multiplexer 26-3. A third input side optical path changer 35-3 is provided, and a fourth input side optical path changer 35- is provided between the third branching unit 22-3 and the fourth input multiplexer 26-4. 4 is provided. Further, a first output side optical path changer 37-1 is provided between the first modulator 31-1 and the first multiplexer 52-1, and the second modulator 31-2 and the first multiplexer 52-1 are provided. A second output side optical path changer 37-2 is provided between the delay unit 42-1 and a third output side between the third modulator 31-3 and the second delay unit 42-2. An optical path changer 37-3 is provided, and a fourth output-side optical path changer 37-4 is provided between the fourth modulator 31-4 and the third delay unit 42-3.

  The support 6 of the OTDM module is provided with an optical clock signal input terminal 61, first to fourth optical data signal input terminals 63-1 to 63-4, and an optical modulation signal output terminal 65. In the plan view of FIG. 6A, the first to fourth optical data signal input terminals 63-1 to 63-4 are not shown, and in the side view of FIG. An optical data signal input terminal 63 is shown.

  The first to fourth optical data signal input terminals 63-1 to 63-4 are provided in one-to-one correspondence with the first to fourth input multiplexers 26-1 to 26-4.

  The optical clock signal input terminal 61 introduces the optical clock signal S101 in the reference plane. Each optical data signal input terminal 63 is attached to the bottom plate 6 or the top plate at a right angle to the reference plane. The optical data signal input terminal 63 introduces the optical data signal S111 from the direction perpendicular to the reference plane. This optical element integrated module is a so-called spatially coupled module in which an optical signal propagates through a space between required optical components.

  In order to realize spatial coupling between optical components, each optical component includes a lens at one or both of an input end and an output end, but description and illustration of the lens are omitted.

  The optical clock signal S101 is bifurcated into a first signal and a second signal by the first branching device 22-1. The second branching device 22-2 further branches the first signal that has been branched into two by the first branching device 22-1 into two, and outputs the first clock signal S103-1 and the third clock signal. S103-3 is generated. The third branching device 22-3 further branches the other second signal that has been branched into two by the first branching device 22-1 into two, and the second clock signal S103-2 and the fourth clock signal. S103-4 is generated.

  The first to fourth clock signals S103-1 to S103-4 are changed in optical path by the first to fourth input-side optical path changers 35-1 to 35-4, respectively, and then the first to fourth input multiplexers 26-1 are used. Sent to ~ 4.

  The first optical data signal S111-1 is input to the first input multiplexer 26-1 of the optical element integrated module through the first optical data signal input terminal 63-1 at a right angle to the reference plane. The second optical data signal S111-2 is input to the second input multiplexer 26-2 of the optical element integrated module through the second optical data signal input terminal 63-2 at a right angle to the reference plane. The third optical data signal S111-3 is input to the third input multiplexer 26-3 of the optical element integrated module through the third optical data signal input terminal 63-3 at a right angle to the reference plane. The fourth optical data signal S111-4 is input to the fourth input multiplexer 26-4 of the optical element integrated module through the fourth optical data signal input terminal 63-4 at a right angle to the reference plane.

  Of the first to fourth optical data signals S111-1 to S111-1 to 4 input to the first to fourth input multiplexers 26-1 to 26-4, they are reflected by the first to fourth input multiplexers 26-1 to 26-4. The component to be transmitted propagates in the reference plane and is sent to the first to fourth modulators 31-1 to 31-4. On the other hand, of the first to fourth optical clock signals S103-1 to S103-1 to 4 input to the first to fourth input multiplexers 26-1 to 26-4, the first to fourth input multiplexers 26-1 to 26-4. The component that passes through the light propagates in the reference plane and is sent to the first to fourth modulators 31-1 to 31-4.

  The first to fourth modulators 31-1 to 31-4 modulate the intensity of the first to fourth optical clock signals S103-1 to S103-1 to generate the first to fourth optical modulation signals S107-1 to S107-4, respectively. . Since the intensity modulation in the first to fourth modulators 31-1 to 31-4 is performed in the same manner as in the first embodiment described above, description thereof is omitted.

  The first optical modulation signal S107-1 is not subjected to a predetermined delay by the delay unit, and the optical path is changed by the first output side optical path changer 37-1, and then to the first multiplexer 52-1. Sent. The second optical modulation signal S107-2 is delayed by T / 4 [s] by the first delay unit 42-1, after the optical path is changed by the second output side optical path changer 37-2. After that, it is sent to the second multiplexer 52-2. The third optical modulation signal S107-3 is delayed by T / 2 [s] by the second delay unit 42-2 after the optical path is changed by the third output side optical path changer 37-3. Thereafter, it is sent to the first multiplexer 52-1. The fourth optical modulation signal S107-4 is subjected to a delay of 3T / 4 [s] by the third delay unit 42-3 after the optical path is changed by the fourth output side optical path changer 37-4. After that, it is sent to the second multiplexer 52-2.

  As a result, a time difference of T / 4 [s] is given between the sequential optical modulation signals of the first to fourth optical modulation signals S107-1 to S107-1.

  The first multiplexer 52-1 multiplexes the first optical modulation signal S107-1 and the third optical modulation signal S107-3 to generate a third signal. The second multiplexer 52-2 multiplexes the second optical modulation signal S107-2 and the fourth optical modulation signal S107-4 to generate a fourth signal. The third multiplexer 52-3 multiplexes the third signal and the fourth signal. As a result, the third multiplexer 52-3 outputs a quadruple OTDM signal S115 obtained by multiplexing the first to fourth optical modulation signals S107-1 to S107-4.

  According to the OTDM module of the second embodiment, when the optical data signal is incident from the direction perpendicular to the reference plane, that is, from the upper surface or the lower surface of the optical element module, the number of multiplexing increases. However, it can be formed compactly without increasing the size of the optical element module.

(Third embodiment)
With reference to FIG. 7, the optical element integrated module of 3rd Embodiment is demonstrated.

  FIG. 7 is a schematic configuration diagram of an optical element integrated module according to the third embodiment, and particularly an enlarged view of an input multiplexer and an optical data signal input terminal.

  The optical element integrated module according to the third embodiment is different from the optical element integrated module according to the second embodiment described with reference to FIG. 6 in that a band-pass filter is used as an input multiplexer, and an optical data signal input terminal The mounting angle to the bottom plate is different. Since the other configuration is the same as that of the second embodiment, a duplicate description is omitted.

  In the optical element integrated module (OTDM module) of the third embodiment, a bandpass filter is used as the input multiplexer 27. Here, the band-pass filter has a boundary wavelength, and either transmission or reflection is performed depending on whether the wavelength of the optical signal is longer or shorter than the boundary wavelength. As the bandpass filter, for example, a conventionally known dielectric multilayer filter can be used. As a band filter, a filter that transmits only a certain wavelength band and reflects other wavelength bands, or a filter that reflects only a certain wavelength band and transmits other wavelength bands may be used.

The wavelength lambda _cl optical clock signal, between the wavelength lambda _d of the optical data signal, there are boundary wavelength lambda _th, transmitted through the optical clock signal of wavelength lambda _cl, the configuration of reflecting optical data signal having a wavelength lambda _d Then, the bandpass filter functions as an input multiplexer. Here, if the optical axis of the bandpass filter is arranged parallel to the optical path of the optical clock signal, the modulator 31 and the optical data signal input terminal cannot be arranged, so the optical axis of the input multiplexer 27 is set to the reference plane. Is tilted at an angle θ.

Similar to the OTDM module of the second embodiment, when an optical data signal is incident from a direction perpendicular to the reference plane, in order to propagate the optical signal reflected by the input wave separator 27 in the reference plane, the optical axis Needs to be inclined 45 degrees with respect to the reference plane. In this case, the band-pass filter of a commercially available 1.5 [mu] m band, a boundary wavelength lambda _th is becomes to 2.1μm (= 1.5μm / cos45 °) , is not practical.

Therefore, the reflection / transmission boundary wavelength λ _th (= λ _th0 / cos θ) of the bandpass filters constituting the first to ²ⁿ input multiplexers is set to about 1.5 μm.

For example, when a band filter of a 1.5 μm band, for example, a band filter having an intrinsic boundary wavelength λ _th0 of 1.52 μm is used, when θ is set to 15 °, the boundary wavelength λ _th is 1.57 μm (= 1.52 μm / cos15 °) and included in the wavelength band used in 1.5 μm band optical communication. Therefore, when using a 1.5 μm band filter, θ should be 15 ° or less.

  Further, when a band filter in the 1.3 μm band is used, when θ is set to 30 °, 1.3 μm / cos 30 ° = 1.5 μm. Accordingly, when using a 1.3 μm band filter, θ should be set to about 30 °.

  At this time, in order to propagate the optical data signal S111 reflected by the bandpass filter in the reference plane, the optical data signal input terminal 64 is provided at an angle of 2 × θ with respect to the reference plane.

  As described above, when the optical multiplexer is configured using the band filter and the reflection and transmission characteristics of the band filter are used, the optical loss in the optical multiplexer can be reduced as compared with the case of using the half mirror. it can. For example, when a half mirror is used for the input multiplexer, only one of the optical data signal and the optical clock signal that is divided into the transmission component and the reflection component is used. For this reason, the optical signal input to the modulator via the input multiplexer has approximately half the intensity of the optical signal input to the module. On the other hand, when the band filter is used, either transmission or reflection is dominant before and after the boundary wavelength. For this reason, the optical signal input to the modulator via the input multiplexer has the same strength as the optical signal input to the module.

  The conditions under which the OTDM module operates are that the bias voltage is −1.2 V, the intensity of the optical clock signal is 17 dBm, and the intensity of the optical data signal is 21 dBm. On the other hand, when the band filter is used, the bias voltage is −1.2 V, the intensity of the optical clock signal is 14 dBm, and the intensity of the optical data signal is 18 dBm. Thus, since the optical intensity of the optical data signal and the optical clock signal is reduced, the power consumed by the optical amplifier can be reduced, leading to lower power consumption.

It is a schematic diagram of signal processing in the optical element integrated module of the present invention. It is a timing chart of the signal processing in the optical element integrated module of this invention. It is a schematic block diagram of the optical element integrated module of 1st Embodiment. It is a schematic block diagram of the other structural example of the optical element integrated module of 1st Embodiment. It is a schematic block diagram of a fiber coupling type optical element integrated module. It is a schematic block diagram of the optical element integrated module of 2nd Embodiment. It is a schematic block diagram of the optical element integrated module of 3rd Embodiment. It is a schematic block diagram of the prior art example of an optical element integrated module.

Explanation of symbols

5, 6 Support body 7, 8 Bottom plate 10, 11, 11a, 12, 13 Optical element integrated module 15 Fiber coupling type optical element integrated module 20 Branching part 21, 22, 28 Branching unit 25 Input multiplexing part 26, 27, 29 Input multiplexer 30 Modulator 31, 32 Modulator 35 Input side optical path changer 37 Output side optical path changer 40 Delay part 41, 42 Delayer 50 Multiplexer 51, 52, 58 Multiplexer 61 Optical clock signal input terminal 62, 63, 64 Optical data signal input terminal 65 Optical modulation signal output terminal 70, 75 Optical amplifier 80 Band pass filter

Claims (7)

A branching unit that branches an optical clock signal having a period T into first to ²ⁿ clock signals (n is an integer of 1 or more);
A modulation unit for generating first to ²ⁿ optical modulation signals by applying intensity modulation to each of the first to ²ⁿ clock signals;
An input multiplexer for sending the first to ²ⁿ optical data signals to the modulator;
A multiplexing unit that combines the first to ²ⁿ optical modulation signals to generate an optical time division multiplexed signal;
An optical element integrated module comprising a delay unit that gives a time difference of T / ²ⁿ between sequential optical modulation signals of the first to ²ⁿ optical modulation signals,
The modulation unit includes first to ²ⁿ modulators, and a kth modulator (k is an integer of 1 to ²ⁿ ) includes a kth clock signal and the kth optical data. A k-th optical modulation signal is generated by the mutual absorption modulation effect with the signal;
The input multiplexer includes first to ²ⁿ input multiplexers, and the kth input multiplexer combines the kth optical data signal and the kth clock signal to generate the first. An optical element integrated module, wherein the optical element integrated module is sent to a modulator of k. Each of the first to ²ⁿ input multiplexers is composed of a half mirror,
The kth input multiplexer reflects the kth optical data signal and sends it to the kth modulator, and transmits the kth clock signal and sends it to the kth modulator. The optical element integrated module according to claim 1. The optical axes of the first to ²ⁿ modulators are provided in the same reference plane,
3. The first to ²ⁿ optical data signals are respectively input to the input multiplexing unit from first to ²ⁿ optical data signal input terminals provided in the reference plane. An optical device integrated module according to 1. The optical axes of the first to ²ⁿ modulators are provided in the same reference plane,
The first to ²ⁿ optical data signals are respectively input to the input multiplexing unit from first to ²ⁿ optical data signal input terminals provided at right angles to the reference plane. The optical element integrated module according to claim 2. The optical axes of the first to ²ⁿ modulators are provided in the same reference plane,
The first to second ⁿ input multiplexers are each composed of a band-pass filter having a natural boundary wavelength λ _th0 of reflection and transmission with respect to light incident along the optical axis,
The optical axes of the first to ²ⁿ input multiplexers are inclined at an angle θ with respect to the reference plane,
The boundary wavelength λ _th (= λ _th0 / cos θ) of reflection and transmission with respect to the light propagating in the reference plane of the band pass filter constituting the first to ²ⁿ input multiplexers is the wavelength λ _{cl of the} optical clock signal. And a value between the wavelength λ _d of the optical data signal,
The first to ²ⁿ optical data signals are input to the input multiplexing unit from first to ²ⁿ optical data signal input terminals provided at an angle of 2 × θ with respect to the reference plane. The optical element integrated module according to claim 1, wherein: A branching unit that branches an optical clock signal having a period T into first to ²ⁿ clock signals (n is an integer of 1 or more);
A modulation unit for generating first to ²ⁿ optical modulation signals by applying intensity modulation to each of the first to ²ⁿ clock signals;
An input multiplexer for sending the first to ²ⁿ optical data signals to the modulator;
A multiplexing unit that combines the first to ²ⁿ optical modulation signals to generate an optical time division multiplexed signal;
An optical element integrated module comprising a delay unit that gives a time difference of T / ²ⁿ between sequential optical modulation signals of the first to ²ⁿ optical modulation signals,
The modulation unit includes first to ²ⁿ modulators, and a kth modulator (k is an integer of 1 to ²ⁿ ) includes a kth clock signal and the kth optical data. A k-th optical modulation signal is generated by the mutual absorption modulation effect with the signal;
The input multiplexing unit includes first to ²ⁿ input multiplexers, and the kth input multiplexer sends the kth optical data signal to the kth modulator. An optical device integrated module. Each of the first to ²ⁿ input multiplexers is composed of a half mirror,
The k-th input multiplexer reflects the k-th optical data signal and sends it to the k-th modulator, and transmits the k-th optical modulation signal to the multiplexing unit. The optical element integrated module according to claim 6.

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