JP2016206430A - Semiconductor light reception detection circuit and optical circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heat generated by reception of signal light.SOLUTION: A semiconductor light reception detection circuit F1 comprises a light reception detection part g1 made of a semiconductor which absorbs and converts at least part of signal light made incident when a reverse bias is applied into a current, and transmits the incident signal light when the reverse bias is no applied. The light reception detection part g1 comprises an optical waveguide structure including a lower clad layer Lyr-01, a core layer Lyr-02 and an upper clad layer Lyr-05, and a pad electrode Lyr-07 formed on the optical waveguide structure and configured to apply the reverse bias. A PL wavelength of the core layer Lyr-02 has a peak on a side which is a 100-200 nm wavelength shorter than a signal light wavelength λ.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor photodetection circuit for monitoring optical output power when adjusting an optical circuit such as a high-speed chaotic optical signal generation optical circuit or an optical signal buffer memory circuit, and an optical circuit including the semiconductor photodetection circuit It is about.

  Chaos signal generation technology includes random numbers used in calculators for device modeling, financial derivative calculations, weather simulations, random numbers used in secret key sharing cryptographic systems, and random numbers used in quantum cryptography communications. Is essential to generate In particular, there is a need for a simple and small high-speed chaotic optical signal generating optical circuit that generates a high-speed chaotic signal exceeding 10 Gb / s.

  FIG. 4 is a block diagram illustrating a configuration of a conventional high-speed chaotic optical signal generating optical circuit disclosed in Patent Document 1. In FIG. The high-speed chaos optical signal generation optical circuit of FIG. 4 is provided from a Mach-Zehnder interference type light intensity modulation unit MZ-1 and an optical output port P-MZ-1-cross described later of the Mach-Zehnder interference type light intensity modulation unit MZ-1. An optical demultiplexing unit SP-1 that demultiplexes the output RZ (Return to Zero) type clock signal light into two systems, and two systems of RZ type clock signal light demultiplexed by the optical demultiplexing unit SP-1. Two systems in which a delay corresponding to an optical propagation delay difference until reaching a later-described optical phase modulator R1, L1 in the Mach-Zehnder interference type optical intensity modulator MZ-1 is input to the optical phase modulator R1, L1 Of the RZ type clock signal light, the optical propagation delay difference providing unit DD-1 for applying to the RZ type clock signal light having a longer optical propagation delay until reaching the optical phase modulation units R1 and L1. Is done.

  The Mach-Zehnder interference type light intensity modulation unit MZ-1 includes an optical input port P-MZ-1-1 that receives an RZ type clock signal light having a constant peak light power output from a clock signal light source (not shown), Two optical interference arms that transmit the RZ type clock signal light input to the input port P-MZ-1-1, and two optical output ports P-MZ- provided at the ends of the two optical interference arms 1-cross, P-MZ-1-bar and two optical signals demultiplexed by the optical demultiplexing unit SP-1 are described later in two optical interference arms of the Mach-Zehnder interferometric light intensity modulating unit MZ-1. Optical phase modulation control optical input ports P-R1 and P-L1 for input to the optical phase modulation units R1 and L1, and one RZ provided for each of the two optical interference arms and transmitted by the optical interference arm Type clock signal light, And an optical phase modulating unit R1, L1 Metropolitan to phase modulation in accordance with the light intensity of the input ports P-R1, RZ type clock signal light input from the P-L1.

  In FIG. 4, 100 is an optical waveguide having one end connected to the optical input port P-MZ-1-1 and the other end connected to the input of the optical phase modulation unit L1, and 101 is disposed close to the optical waveguide 100. An optical waveguide having the other end connected to the input of the optical phase modulation unit R1, and an optical waveguide 102 having one end connected to the output of the optical phase modulation unit L1 and the other end connected to the optical output port P-MZ-1-bar , 103 is an optical waveguide having one end connected to the output of the optical phase modulation unit R1, the other end connected to the optical output port P-MZ-1-cross, and a part thereof arranged close to the optical waveguide 102.

  The optical waveguides 100 and 102 constitute one optical interference arm of the Mach-Zehnder interference type light intensity modulation unit MZ-1, and the optical waveguides 101 and 103 constitute the other optical interference arm of the Mach-Zehnder interference type light intensity modulation unit MZ-1. Is configured. An optical signal leaks between the optical waveguide 100 and the optical waveguide 101, and the optical signal input to the optical waveguide 100 is also input to the optical waveguide 101. The optical signal leaks between the optical waveguide 102 and the optical waveguide 103.

  An optical waveguide 104 has one end connected to the optical output port P-MZ-1-cross and the other end connected to the input of the optical demultiplexing unit SP-1, and 105 has one end connected to the optical demultiplexing unit SP-1. An optical waveguide connected to the first output and having the other end connected to the input of the optical propagation delay difference applying unit DD-1, and one end connected to the second output of the optical demultiplexing unit SP-1 An optical waveguide having one end connected to the optical input port P-R1, 109 is an optical waveguide having one end connected to the output of the optical propagation delay difference adding unit DD-1 and the other end connected to the optical input port P-L1 It is.

  FIG. 5 shows changes in the optical power of the clock signal light input to the optical input port P-MZ-1-1. Thus, the clock signal light input from the clock signal light source (not shown) to the optical input port P-MZ-1-1 is RZ type signal light having a constant peak light power.

  In a standard Mach-Zehnder interferometric light intensity modulation unit, a state in which no phase difference occurs when light propagates through the two optical interference arms constituting the interferometer is a state in which modulation driving is not performed. Sometimes, 100% of the optical signal is output from the optical output port of the optical interference arm on the different side with respect to the optical interference arm on the input side. In a state where the phase difference is π when light propagates through the two optical interference arms, 100% of the optical signal is output from the optical output port of the optical interference arm on the same side as the optical input port.

  Therefore, when the clock signal light is input from the optical input port P-MZ-1-1 to the high-speed chaotic optical signal generation optical circuit shown in FIG. 4, the first clock optical pulse p0 is the optical input port P-MZ- 100% is output from the optical output port P-MZ-1-cross of the optical interference arm on the side different from 1-1, and is divided into two of the clock optical pulses p0-1 and p0-2 by the optical demultiplexing unit SP-1. Then, after being delayed by the optical propagation delay difference adding unit DD-1, the signals are input from the optical input ports P-R1 and P-L1 to the optical phase modulating units R1 and L1, respectively.

6A shows the input timing of the input clock signal light to the optical input port P-MZ-1-1. FIG. 6B shows the input timing of the input signal light to the optical phase modulator R1. FIG. 6C is a diagram showing the input timing of the input signal light to the optical phase modulation unit L1.
As shown in FIG. 6B, the optical propagation delay difference is applied at the timing between the clock light pulse p0 input to the optical input port P-MZ-1-1 and the clock light pulse p1 of the next time step. The clock optical pulse p0-1 to which the optical propagation delay by the unit DD-1 is not given is input to the optical phase modulation unit R1. On the other hand, as shown in FIG. 6C, the optical propagation delay is applied by the optical propagation delay difference providing unit DD-1 at the timing between the clock optical pulse p1 and the clock optical pulse p2 of the next time step. The generated clock light pulse p0-2 is input to the optical phase modulator L1.

  In the optical phase modulation unit R1, the clock light pulse p0− is output from the optical input port P-R1 immediately before the clock light pulse p1 is input from the optical input port P-MZ-1-1 through the optical waveguides 100 and 101. When 1 is input, the refractive index changes according to the light intensity of the clock light pulse p0-1. Thus, the optical phase modulation unit R1 modulates the phase of the clock light pulse p1 according to the light intensity of the clock light pulse p0-1 (mutual phase modulation).

  On the other hand, in the optical phase modulation unit L1, the clock light pulse p0− is output from the optical input port P-L1 immediately after the clock light pulse p1 is input from the optical input port P-MZ-1-1 via the optical waveguide 100. When 2 is input, the refractive index changes according to the light intensity of the clock light pulse p0-2. Thus, the optical phase modulation unit L1 modulates the phase of the clock light pulse p2 in accordance with the light intensity of the clock light pulse p0-2 (mutual phase modulation).

  As a result, the Mach-Zehnder interferometric light intensity modulator MZ from when the clock light pulse p0-1 is input to the optical phase modulator R1 to when the clock light pulse p0-2 is input to the optical phase modulator L1. −1 causes a phase difference between the two optical interference arms, and the optical output intensity of the clock optical pulse p1 output from the optical output port P-MZ-1-cross is modulated.

  Similarly, it is demultiplexed by the optical demultiplexing unit SP-1 at the timing between the clock optical pulse p1 input to the optical input port P-MZ-1-1 and the clock optical pulse p2 of the next time step. Of the clock light pulses p1-1 and p1-2, the clock light pulse p1-1 to which the light propagation delay by the light propagation delay difference applying unit DD-1 is not applied is input to the optical phase modulation unit R1. . On the other hand, at the timing between the clock light pulse p2 and the clock light pulse p3 of the next time step, the clock light pulse p1-2 to which the light propagation delay is imparted by the light propagation delay difference imparting unit DD-1 is provided. Is input to the optical phase modulator L1.

  The optical phase modulation unit R1 receives a clock light pulse p1 that is a demultiplexed light of the clock light pulse p1 immediately before the clock light pulse p2 is input from the optical input port P-MZ-1-1 via the optical waveguides 100 and 101. When −1 is input from the optical input port P-R1, the phase of the clock light pulse p2 is modulated according to the light intensity of the clock light pulse p1-1.

  The optical phase modulation unit L1 receives a clock light pulse p1-2 that is a demultiplexed light of the clock light pulse p1 immediately after the clock light pulse p2 is input from the optical input port P-MZ-1-1 via the optical waveguide 100. Is input from the optical input port P-L1, the phase of the clock light pulse p3 is modulated in accordance with the light intensity of the clock light pulse p1-2. As a result, the optical output intensity of the clock optical pulse p2 output from the optical output port P-MZ-1-cross is modulated.

  As described above, at the timing between the clock light pulse p (t) (t = 0, 1, 2, 3,...) And the clock light pulse p (t + 1) of the next time step, One clock optical pulse p (t) output from the output port P-MZ-1-cross and demultiplexed by the optical demultiplexing unit SP-1 is input to the optical phase modulation unit R1, and the clock optical pulse p (t + 1) And the other optical clock pulse output from the optical output port P-MZ-1-cross and demultiplexed by the optical demultiplexing unit SP-1 at a timing between the optical optical pulse p (t + 2) of the next time step. p (t) is input to the optical phase modulator L1. As a result, the optical output intensity of the clock optical pulse p (t + 1) output from the optical output port P-MZ-1-cross is modulated. Thus, the modulation of the clock light pulses p1, p2, p3,.

  FIG. 7 is a diagram showing a normalized light output intensity obtained by normalizing the light intensity of the clock light pulse output from the light output port P-MZ-1-cross of the Mach-Zehnder interference type light intensity modulator MZ-1. This shows a case where the amount of phase modulation generated in the clock light pulse of the next time step by the clock light pulse output from the optical output port P-MZ-1-cross is 1.8261π.

  The clock output from the optical output port P-MZ-1-cross under the condition that the output is 100% from the optical output port P-MZ-1-cross of the Mach-Zehnder interference type optical intensity modulator MZ-1. By setting the optical phase modulators R1 and L1 so that the amount of phase modulation generated by the optical pulse in the clock optical pulse of the next time step is sufficient and appropriate, for example, as shown in FIG. The intensity of the clock light pulse output from the optical output port P-MZ-1-cross becomes a chaotic state in time series, and at the same time, the intensity of the clock light pulse output from the optical output port P-MZ-1-bar is also It becomes a chaotic state in time series.

  As described above, the conventional high-speed chaotic optical signal generation optical circuit can generate a high-speed chaotic signal. Further, the conventional high-speed chaotic optical signal generation circuit has the configuration shown in FIG. 8 in order to realize reproducibility and controllability that are essential in engineering.

  Here, FIG. 8 is a block diagram illustrating a configuration example of the optical phase modulation unit R1. The optical phase modulation unit R1 is a Mach-Zehnder interference circuit and is transmitted by the optical interference arm (101 in FIG. 4) of the Mach-Zehnder interference type optical intensity modulation unit MZ-1 and input to the optical input port 1007. RZ type clock signal light (hereinafter referred to as phase modulation) that is demultiplexed by the optical demultiplexing unit SP-1 and input to the optical input port 1008 (P-R1 in FIG. 4). Multimode interference coupler (MMI) b1, which is an optical interference type multiplexing / branching means for multiplexing the combined signal light into two systems, and outputting from the multimode interference coupler b1 Optical waveguide type that multiplexes two signal lights transmitted by two optical waveguide arms and demultiplexes the combined signal light into two systems Is a branching means A multi-mode interference coupler b2, optical phase modulation control units c1 and c2 that are provided one by one on two optical waveguide arms and phase-modulate the phase-modulated signal light according to the light intensity of the phase modulation control signal light, A phase adjustment unit d1 provided on one of the optical waveguide arms and capable of adjusting the phase of the signal light in accordance with the amount of injection current supplied from the outside, and one optical output port of the multimode interference coupler b2 It is comprised from the connected light-receiving part f1. In FIG. 8, reference numeral 1009 denotes an optical output port of the optical phase modulation unit R1 connected to the optical waveguide 103 shown in FIG. The configuration of the optical phase modulation unit L1 is the same as that of the optical phase modulation unit R1.

  The phase adjustment unit d1 can adjust the phase of the signal light according to the amount of injection current supplied from the outside. By adjusting the phase of the signal light output from the optical phase modulation control unit c1 by the phase adjustment unit d1, the phase-modulated signal light is connected to the second optical output port (connected to the optical waveguide 1019) of the multimode interference coupler b2. The phase modulation control signal light is selectively output from the first optical output port (optical output port connected to the optical waveguide 1018) of the multimode interference coupler b2. In addition, the phase difference between the two optical waveguide arms can be adjusted after manufacturing. As a result, sufficient optical phase modulation can be realized in the optical phase modulation units R1 and L1.

For the adjustment, the optical output power from the optical output port P-MZ-1-cross is measured and evaluated, and the optical output power detected by the light receiving unit f1 of the optical phase modulation unit R1 is evaluated to thereby adjust the phase output. The modulated signal light is selectively output from the second optical output port of the multimode interference coupler b2 of the optical phase modulator R1, and the phase modulation control signal light is output from the first of the multimode interference coupler b2 of the optical phase modulator R1. The phase adjustment unit d1 of the optical phase modulation unit R1 can be adjusted so as to be selectively output from the optical output port.
By adjusting in this way, the conventional high-speed chaotic optical signal generation circuit can realize reproducibility and controllability that are essential in engineering.

A high-speed optical signal buffer memory circuit that outputs a delayed optical signal is also an important technology in optical processing and optical computers.
FIG. 9 is a block diagram illustrating a configuration of a conventional optical signal buffer memory circuit disclosed in Patent Document 2, and FIG. 10 is a timing chart of various optical signal trains in the optical signal buffer memory circuit.

  In the optical signal buffer memory circuit shown in FIG. 9, P-OCLK-In is an external optical input port for the clock signal light CLK-1 as shown by “OC source” in FIG. The clock signal light CLK-1 is a clock light pulse output from the clock signal light source, and is RZ type clock signal light having a constant peak light power.

  P-Data-In is an external optical input port of the optical signal sequence Data-1 as shown by “OD source” in FIG. The optical signal string Data-1 is an optical signal string for data input for the purpose of storing in the optical signal buffer memory circuit.

  P-FF-In is an external optical input port of the optical signal sequence FF-1 as shown in “FF cntl.” In FIG. The optical signal sequence FF-1 is input when a so-called flip-flop operation is performed to invert all the information marks (1) and spaces (0) of the data optical signal sequence stored in the optical signal buffer memory circuit. This is an optical signal train for flip-flop control.

  P-ERS-In is an external optical input port of the optical signal train ERS-1 as shown by “ERS cntl.” In FIG. The optical signal string ERS-1 is an optical signal string for erasure control that is input when information stored in the optical signal buffer memory circuit is reset.

  C-2 has optical input ports P-C2-1 and P-C2-2 and optical output ports P-C2-3 and P-C2-4, and light is transmitted from the external optical input port P-Data-In. From the input optical signal string Data-1 input to the optical input port P-C2-1 through the waveguide 16 and the external optical input port P-ERS-In to the optical input port P-C2-2 through the optical waveguide 17. The inputted input optical signal train ERS-1 is output from the same optical output port P-C2-4, and then to one optical input port P-C1-1 of the subsequent 2 × 2 optical branching unit C-1. This is a 2 × 1 optical multiplexing part for coupling to the guiding optical waveguide 18.

  R1-1, R1-2, L1-1, and L1-2 are input from the external light input port P-OCLK-In to the Mach-Zehnder interference type light intensity modulation unit MZ-1, and the Mach-Zehnder interference type light intensity is input. Clock optical signal sequence propagating through the left and right optical interference arms of the modulation unit MZ-1 (the optical interference arm configured by the optical waveguides 11R, 12R, and 13R and the optical interference arm configured by the optical waveguides 11L, 12L, and 13L) It is an optical phase modulation part which modulates the phase of.

  The optical phase modulators R1-1, R1-2, L1-1, and L1-2 are disposed between the two directional couplers. Specifically, the optical phase modulator R1-1 includes the optical waveguide 11R. Between the optical waveguide 12R, the optical phase modulator R1-2 between the optical waveguide 12R and the optical waveguide 13R, and the optical phase modulator L1-1 between the optical waveguide 11L and the optical waveguide 12L. The phase modulation unit L1-2 is disposed between the optical waveguide 12L and the optical waveguide 13L. That is, the optical phase modulation unit R1-2 is located on the rear side of the optical phase modulation unit R1-1, and the optical phase modulation unit L1-2 is located on the rear side of the optical phase modulation unit L1-1.

  C-1 includes optical input ports P-C1-1 and P-C1-2 and optical output ports P-C1-3 and P-C1-4, and the optical output of the optical multiplexing unit C-2. The optical signal train from the port P-C2-4 is input from the optical input port P-C1-1 and branched through the optical waveguide 18, and is split into the optical output ports P-C1-3 and P-C1-4. The optical signal train from the optical output port P-MZ-1-bar of the Mach-Zehnder interference type optical intensity modulator MZ-1 is output via the optical waveguide 14 to the optical input port P-C1- 2 is an optical branching section for inputting and branching from 2 and outputting from the optical output ports P-C1-3 and P-C1-4.

  P-R1-1 and P-L1-1 transmit optical signal sequences output from the optical output ports P-C1-4 and P-C1-3 of the optical branching unit C-1 via the optical waveguides 15R and 15L. This is an optical input port for inputting to the optical phase modulators R1-1 and L1-1 in the two optical interference arms of the Mach-Zehnder interference type optical intensity modulator MZ-1.

  C-3 has optical input ports P-C3-1 and P-C3-2 and optical output ports P-C3-3 and P-C3-4, and light is transmitted from the external optical input port P-FF-In. This is an optical branching unit for branching an optical signal string input via the waveguide 21 and outputting it from the optical output ports P-C3-3 and P-C3-4.

  P-R1-2 and P-L1-2 pass the optical signal sequence output from the optical output ports P-C3-4 and P-C3-4 of the optical branching unit C-3 via the optical waveguides 22R and 22L. This is an optical input port for inputting to the optical phase modulation units R1-2 and L1-2 in the two optical interference arms of the Mach-Zehnder interference type optical intensity modulation unit MZ-1.

  D-D-1 is branched by the optical branching unit C-1, and optical phase modulation units R1-1 and R1-1 are respectively added to two optical signal sequences output from the optical output ports P-C1-3 and P-C1-4. An optical propagation delay difference providing unit for providing an optical propagation delay difference until reaching L1-1 so as to be “more than the pulse width of the clock optical signal CLK-1 and less than the pulse repetition period”. An optical waveguide portion having an optical path length that generates a light propagation delay difference is disposed in the optical waveguide 15L.

  The D-D-2 is branched by the optical branching unit C-3, and two optical signal sequences output from the optical output ports P-C3-3 and P-C3-4 are respectively added to the optical phase modulation units R1-2 and L1. -2 is an optical propagation delay difference providing unit for providing an optical propagation delay difference until reaching -2 so as to be "more than the pulse width of the clock optical signal CLK-1 and less than the pulse repetition period". An optical waveguide portion having an optical path length causing a propagation delay difference is arranged in the optical waveguide 22L.

Next, operations in the optical signal buffer memory circuit, specifically, data holding (buffering) operation will be described with reference to FIG.
When the clock signal light CLK-1 is input from the external optical input port P-OCLK-In to the optical signal buffer memory circuit, the clock optical signal CLK-1 is output from the 100% optical output port P-MZ-1-cross. Thus, no optical output can be obtained from the optical output port P-MZ-1-bar (empty state in which the optical signal buffer memory circuit does not hold any information: initial state).

  At this time, as shown in “OD source” of FIG. 10, when the optical signal sequence Data-1 synchronized with the clock signal light CLK-1 is input from the external optical input port P-Data-In, The phase modulators R1-1 and L1-1 are driven. The optical phase modulators R1-1 and L1-1 are the first clock optical signal train (clock signal light CLK-1) propagating through the two optical interference arms of the Mach-Zehnder interference type optical intensity modulator MZ-1. ) Is π-modulated according to the optical signal sequence Data-1, and each pulse of the first clock optical signal sequence is turned on or off.

  By such an operation, π phase modulation is applied only to the clock pulse of the first clock optical signal sequence corresponding to the pulse at the position of Mark (1) in the optical signal sequence Data-1, and the optical signal sequence Data Since the phase modulation is not applied to the clock pulse of the first clock optical signal sequence corresponding to the pulse at the position of −1 Space (0), the same data pattern as the optical signal sequence Data-1 has Mach-Zehnder interference. Is output from the light output port P-MZ-1-bar of the mold light intensity modulator MZ-1. In FIG. 10, an 8-bit optical signal string “10101010” is input as an example of the optical signal string Data-1.

  Then, the optical signal sequence CLK-1-out-DMZ1 having the same data pattern as the optical signal sequence Data-1 is transmitted from the optical output port P-MZ-1-bar of the Mach-Zehnder interference type optical intensity modulation unit MZ-1. The light is input to the optical phase modulators R1-1 and L1-1 via the branching unit C-1 to induce optical phase modulation.

  Therefore, also in the next round, the first clock optical signal sequence propagating through the two optical interference arms of the Mach-Zehnder interference type optical intensity modulation unit MZ-1 is the same data as the optical signal sequence Data-1. An optical output port of the Mach-Zehnder interferometric light intensity modulator MZ-1 is subjected to the optical phase modulation similar to the above by the optical signal sequence CLK-1-out-DMZ1 of the pattern, and the same data pattern as the optical signal sequence Data-1 Output from P-MZ-1-bar is repeated. As a result, as shown in “Buffering State” in FIG. 10, the same data pattern as the optical signal sequence Data-1 is held in the optical signal buffer memory circuit as a series of driving states.

  Here, the optical phase modulators R1-1, R1-2, L1-1, and L1-2 are formed on the compound semiconductor substrate. FIGS. 11A, 11B, and 11C are block diagrams illustrating a configuration example of the optical phase modulation unit R1-1. 11A, 11B, and 11C, a1 and a2 are two optical input / output ports on one side of the optical phase modulator R1-1, and a3 and a4 are optical phase modulators R1. -1 are two optical input / output ports on the other side, b1 and b2 are multimode interference couplers (first and second optical interference type branching means), and a9 and a10 are optical inputs of one of the multimode interference coupler b1. Output ports, a5 and a6 are the other optical input / output ports of the multimode interference coupler b1, a7 and a8 are the one optical input / output ports of the multimode interference coupler b2, and a11 and a12 are the other lights of the multimode interference coupler b2. Input / output ports, e1 and e2 are two optical input / output waveguides on one side of the optical phase modulator R1-1, e3 and e4 are two optical input / output waveguides on the other side of the optical phase modulator R1-1, c1 and c2 are two optical phase modulation control units, 1, d2 is a phase adjusting unit. The optical waveguides e5 and e7 constitute one optical waveguide arm in the optical phase modulation unit R1-1, and the optical waveguides e6 and e8 constitute the other optical waveguide arm in the optical phase modulation unit R1-1.

  The optical input / output ports a1 and a2 of the optical phase modulator R1-1 are connected to the optical input / output ports a9 and a10 of the multimode interference coupler b1 via optical input / output waveguides e1 and e2, respectively. The optical input / output ports a5 and a6 of the multimode interference coupler b1 are connected to one of the ports of the optical phase modulation controllers c1 and c2 via the optical waveguides e5 and e6, respectively. The other ports of the optical phase modulation controllers c1 and c2 are connected to optical input / output ports a7 and a8 of the multimode interference coupler b2 via optical waveguides e7 and e8, respectively. That is, the optical phase modulation control units c1 and c2 are provided in each of the two optical waveguide arms of the optical phase modulation unit R1-1. The optical input / output ports a11 and a12 of the multimode interference coupler b2 are connected to the optical input / output ports a3 and a4 of the optical phase modulator R1-1 via two optical input / output waveguides e3 and e4, respectively.

  The phase adjusters d1 and d2 can adjust the phase of the signal light according to the amount of injected current, and are provided on one or both of the two optical waveguide arms of the optical phase modulator R1-1. That is, in the configuration example of the optical phase modulation unit R1-1 illustrated in FIG. 11A, the phase adjustment unit d1 is provided in the optical waveguide e7, and another optical phase modulation unit R1-1 illustrated in FIG. In the configuration example, the phase adjustment unit d2 is provided in the optical waveguide e8. In another configuration example of the optical phase modulation unit R1-1 illustrated in FIG. 11C, the phase adjustment units d1 and d2 are provided in the optical waveguides e7 and e8. Each is provided.

  In the multimode interference coupler b1, the optical signal sequence Data-1 or the optical signal sequence CLK-1-out-DMZ1 which is the optical phase modulation control signal light is transmitted to the optical input / output port a1 (see FIG. 9) of the optical phase modulation unit R1-1. The clock signal light CLK-1 which is input to the optical input / output port a9 via the P-R1-1) and is the optical phase-modulated signal light is optically transmitted via the optical input / output port a2 of the optical phase modulator R1-1. When input to the input / output port a10, the optical phase modulation signal light and the optical phase modulation control signal light are branched, and one of the branched optical phase modulation signal light and one of the optical phase modulation control signal light is combined. And is output from the optical input / output port a5, and the other of the branched optical phase modulation signal light and the other of the optical phase modulation control signal light are combined and output from the optical input / output port a6.

  For example, when the two signal lights Sig-1 and Sig-2 output from the optical phase modulation controllers c1 and c2 are input to the optical input / output ports a7 and a8, respectively, the multimode interference coupler b2 receives the signal light Sig−. 1 and the signal light Sig-2 are respectively branched, one of the branched signal light Sig-1 and one of the signal light Sig-2 are combined and output from the optical input / output port a11, and the branched signal light Sig- 1 and the other of the signal light Sig-2 are combined and output from the optical input / output port a12. The signal light output from the optical input / output port a12 is output to the optical waveguide 12R via the optical input / output port a4 of the optical phase modulator R1-1.

  The optical phase modulation controllers c1 and c2 have an optical waveguide structure having a property that the refractive index changes according to the optical intensity of the optical phase modulation control signal light, and an optical semiconductor amplifier (SOA: Semiconductor Optical) having an optical waveguide structure. Amplifier), an optical waveguide structure including a quantum dot layer, or a semiconductor EA (Electro-Absorption) modulator in a constant voltage driving state. The optical phase modulation controller c1 is disposed between the optical waveguides e5 and e7, and the optical phase modulation controller c2 is disposed between the optical waveguides e6 and e8.

As described above, the optical phase modulation unit R1-1 includes a Mach-Zehnder interference circuit in which two multimode interference couplers (MMI) b1 and b2 are connected by two optical waveguide arms including the optical phase modulation control units c1 and c2. It is composed. The optical path lengths of the two optical waveguide arms of the Mach-Zehnder interference circuit are strictly adjusted at the time of use by using the phase adjusters d1 and d2.
The configuration of the optical phase modulators R1-2, L1-1, and L1-2 is the same as that of the optical phase modulator R1-1.

  In the optical phase modulation unit R1-1, the optical signal sequence Data-1 or the optical signal sequence CLK-1-out-DMZ1 serving as the optical phase modulation control signal light is transmitted from the optical input / output port a1 (P-R1-1 in FIG. 9). ). The first clock optical signal sequence (CLK-1) that becomes the optical phase-modulated signal light is input to the optical input / output port a2 (optical input / output port connected to the optical waveguide 11R) of the optical phase modulator R1-1. Is done. By adjusting the phase adjusters d1 and d2, the first clock subjected to the optical phase modulation from the optical input / output port a4 (the optical input / output port connected to the optical waveguide 12R) of the optical phase modulator R1-1. Only the optical signal train is selectively output. Further, only the optical signal sequence Data-1 or the optical signal sequence CLK-1-out-DMZ1 which is the optical phase modulation control signal light is selectively output from the optical input / output port a3 of the optical phase modulation unit R1-1. .

  Similarly, in the optical phase modulation unit L1-1, the optical signal sequence Data-1 or the optical signal sequence CLK-1-out-DMZ1 serving as the optical phase modulation control signal light is transmitted to the optical input / output port a1 (P- in FIG. 9). L1-1). The first clock optical signal string (CLK-1) that is the optical phase-modulated signal light is input to the optical input / output port a2 (optical input / output port connected to the optical waveguide 11L) of the optical phase modulator L1-1. Is done. By adjusting the phase adjusters d1 and d2, the first clock subjected to the optical phase modulation from the optical input / output port a4 (the optical input / output port connected to the optical waveguide 12L) of the optical phase modulator L1-1. Only the optical signal train is selectively output. Further, only the optical signal sequence Data-1 or the optical signal sequence CLK-1-out-DMZ1 which is the optical phase modulation control signal light is selectively output from the optical input / output port a3 of the optical phase modulation unit L1-1. .

  In the optical phase modulation unit R1-2, the optical signal sequence FF-1 for flip-flop control, which is the optical phase modulation control signal light, is input to the optical input / output port a1 (P-R1-2 in FIG. 9). The optical phase-modulated signal light is a first clock optical signal sequence (second clock optical signal sequence) after being subjected to optical phase modulation by the optical phase modulation unit R1-1. The light phase modulated signal light is input to the optical input / output port a4 (optical input / output port connected to the optical waveguide 12R) of the optical phase modulator R1-2. By adjusting the phase adjusting units d1 and d2, the second clock light subjected to the optical phase modulation from the optical input / output port a2 (optical input / output connected to the optical waveguide 13R) of the optical phase modulating unit R1-2. Only the signal train is selectively output. Further, only the optical signal string FF-1 that is the optical phase modulation control signal light is selectively output from the optical input / output port a3 of the optical phase modulation unit R1-2.

  In the optical phase modulation unit L1-2, the optical signal sequence FF-1 for flip-flop control, which is the optical phase modulation control signal light, is input to the optical input / output port a1 (P-L1-2 in FIG. 9). The optical phase-modulated signal light is a first clock optical signal sequence (second clock optical signal sequence) after being subjected to optical phase modulation by the optical phase modulation unit L1-1. The light phase modulated signal light is input to the optical input / output port a4 (optical input / output port connected to the optical waveguide 12L) of the optical phase modulator L1-2. By adjusting the phase adjusting units d1 and d2, the second clock light subjected to the optical phase modulation from the optical input / output port a2 (optical input / output connected to the optical waveguide 13L) of the optical phase modulating unit L1-2. Only the signal train is selectively output. Further, only the optical signal sequence FF-1 that is the optical phase modulation control signal light is selectively output from the optical input / output port a3 of the optical phase modulation unit L1-2.

  Next, the light receiving part f1 provided in the optical phase modulation parts R1-1, R1-2, L1-1, and L1-2 will be described. Desired “signal light-control light separation operation” in the optical phase modulation units R1-1, R1-2, L1-1, and L1-2, for example, a received light such as a clock optical signal string input from the optical input / output port a2. The phase modulation signal light is selectively output from the optical input / output port a4, and the optical phase modulation control signal light such as the optical signal train CLK-1-out-DMZ1 input from the optical input port a1 is input to the optical input / output port a3. Therefore, the balance of the effective length of the two optical waveguide arms constituting the interference system with respect to the signal light needs to be precisely adjusted.

  Therefore, in the configuration shown in FIGS. 11A to 11C, an optical input that becomes an output port of the optical phase modulation control signal light such as the optical signal train CLK-1-out-DMZ1 subjected to the optical intensity modulation. A light receiving portion f1 is provided at the output port a3. Based on the optical power detected by the light receiving unit f1, it is possible to perform initial adjustment of the effective length of the optical waveguide arms of the optical phase modulation units R1-1, R1-2, L1-1, and L1-2. .

  As described above, both the high-speed chaotic optical signal generating optical circuit shown in FIG. 4 and the optical signal buffer memory circuit shown in FIG. 9 are optical phase modulators R1, L1, R1-1, R1- that are Mach-Zehnder interference circuits. 2, a light receiving section f1 is provided for adjusting the phase adjusting sections d1 and d2 in L1-1 and L1-2.

  As the light receiving unit f1, for example, when the operating wavelength region of the optical circuit is a 1.5 μm band that is an optical communication wavelength band, as shown in FIGS. 12B and 12C, the communication wavelength A light receiving section using an InGaAs crystal exhibiting light absorption characteristics in a light wavelength band as a light receiving layer is used (see Non-Patent Document 1). 12A is a plan view of a portion where the light receiving portion f1 of the optical phase modulation portion R1-1 is provided, FIG. 12B is a cross-sectional view taken along the line II of FIG. 12A, and FIG. ) Is a cross-sectional view taken along line II-II in FIG.

  As shown in FIG. 12B, the optical waveguide e3 includes a lower cladding layer Lyr-01 made of n-InP, a core layer Lyr-02 made of InGaAsP, an n-InP layer Lyr-03, and p-InP. The upper clad layer Lyr-05 made of and the contact layer Lyr-06 made of InGaAs.

  As shown in FIG. 12C, the light receiving portion f1 includes a light receiving layer Lyr-04 between the n-InP layer Lyr-03 and the upper clad layer Lyr-05, and is formed on the contact layer Lyr-06. A pad electrode Lyr-07 made of Au is formed.

JP 2014-052948 A JP 2014-174303 A

M. Kohtoku, H. Sanjoh, S. Oku, Y. Kadota, and Y. Yoshikuni, “Packaged Polarization-Insensitive WDM Monitor with Low Loss (7.3 dB) and Wide Tuning Range (4.5 nm)”, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL.10, NO.11, NOVEMBER 1998, pp.1614-1616

  However, if a light-receiving layer that exhibits efficient light absorption characteristics in the operating wavelength region of the optical circuit is used for the light-receiving unit, extremely good light-receiving characteristics can be obtained, but the optical circuit is driven not only during initial adjustment. In this case, the signal light that is desired to be discarded without affecting the driving operation is efficiently absorbed by the light receiving unit, and heat is generated in the light receiving unit due to the generation of current due to the absorption. It will be.

  In particular, when the signal light power during driving operation is large, this heat generation from the light receiving part induces thermal expansion and refractive index change with local and temporal variation in the optical circuit. Therefore, the balance of the optical phase modulation unit which is a Mach-Zehnder interference circuit is lost, the desired characteristics of the optical phase modulation unit are deteriorated, and thus a high-speed chaotic optical signal generation optical circuit or optical signal buffer that includes the optical phase modulation unit There has been a problem of deteriorating the desired operating characteristics of the memory circuit.

  The present invention has been made to solve the above problems, and an object thereof is to provide a semiconductor light receiving detection circuit and an optical circuit capable of reducing heat generated by receiving signal light.

The present invention is a semiconductor photodetection circuit that forms part of an optical circuit through which signal light of wavelength λ propagates, absorbs at least part of the incident signal light when a reverse bias is applied, and converts it into a current. A light receiving detector g1 made of a semiconductor that transmits incident signal light when no reverse bias is applied is provided. The light receiving detector g1 includes a lower cladding layer, a core layer formed on the lower cladding layer, and a core layer An optical waveguide structure including an upper clad layer formed thereon, and an electrode for applying the reverse bias formed on the optical waveguide structure, wherein the PL wavelength of the core layer is the wavelength λ Further, it has a peak on the short wavelength side of 100 to 200 nm.
Further, one configuration example of the semiconductor light reception detection circuit of the present invention further includes a first optical waveguide a3-in for guiding the signal light to the light reception detection unit g1, and the first optical waveguide a3-in. A second optical waveguide a3-out that is formed so as to be coupled to the end of the light receiving detection part g1 on the opposite side and guides the signal light that has passed through the light receiving detection part g1 to the end face of the optical circuit; The non-reflective coating film AR-1 formed on the end face of the optical circuit from which the signal light guided by the optical waveguide a3-out is emitted.

In one configuration example of the semiconductor photodetection circuit of the present invention, the core layer of the first optical waveguide a3-in, the core layer of the photodetection part g1, and the core layer of the second optical waveguide a3-out Are characterized by having the same composition.
In the configuration example of the semiconductor photodetection circuit of the present invention, the first optical waveguide a3-in, the optical waveguide structure of the photodetection part g1, and the second optical waveguide a3-out have the same composition. It is characterized by comprising.
Further, in one configuration example of the semiconductor light reception detection circuit of the present invention, the first optical waveguide a3-in and the optical waveguide structure of the light reception detection part g1 have the same waveguide width. It is.

The optical circuit of the present invention includes a semiconductor light receiving detection circuit.
Also, one configuration example of the optical circuit according to the present invention includes two lights, a Mach-Zehnder interference type light intensity modulating unit MZ-1 for inputting the RZ type clock signal light and the Mach-Zehnder interference type light intensity modulating unit MZ-1. Optical demultiplexing means SP-1 for demultiplexing the RZ-type clock signal light output from any one of the output ports P-MZ-1-cross and P-MZ-1-bar into two systems, and this light Two systems of RZ type clock signal light demultiplexed by the demultiplexing means SP-1 are guided to the optical phase modulation means in the Mach-Zehnder interference light intensity modulation means MZ-1 as clock signal lights for phase modulation control. The Mach-Zehnder interference type optical intensity modulation means MZ-1 includes an optical input port P-MZ-1-1 for receiving the RZ type clock signal light, and the optical input port P-MZ. 1-1 Two optical interference arms that transmit the applied RZ type clock signal light, and the two optical output ports P-MZ-1-cross, P-MZ-1 provided at the ends of the two optical interference arms -Bar and the RZ type clock signal light provided by the two optical interference arms and transmitted by the optical interference arm, and the light intensity of the RZ type clock signal light input from the third optical waveguide. The optical phase modulation means R1 and L1 that perform phase modulation in accordance with the optical phase modulation means R1 and L1, respectively. A first optical interference type multiplexing / branching unit that multiplexes the light and splits the combined signal light into two systems, and two systems of signal light output from the first optical interference type multiplexing / branching unit Two lights that transmit A second optical interference type multiplexing / branching unit that multiplexes two systems of signal light transmitted by the two optical waveguide arms and demultiplexes the combined signal light into two systems; An optical phase modulation control means for phase-modulating the clock signal light transmitted by the optical interference arm according to the light intensity of the clock signal light for phase modulation control, provided one by one on one optical waveguide arm; Phase adjusting means provided on at least one of the two optical waveguide arms and capable of adjusting the phase of the signal light in accordance with the amount of injected current supplied from the outside; and the second optical interference type coupling / branching The semiconductor light receiving detection circuit for receiving the signal light output from the one not connected to the optical interference arm among the two optical output ports of the means, and further provided in the third optical waveguide , The optical demultiplexing A delay corresponding to the difference in optical propagation delay until the two systems of RZ type clock signal light demultiplexed by the means SP-1 reach the optical phase modulation means R1, L1 is given to the optical phase modulation means R1, L1. Of the two input RZ type clock signal lights, the optical propagation delay difference providing means D− provided to the RZ type clock signal light having the longer optical propagation delay until reaching the optical phase modulation means R1, L1. Among the two optical output ports of the second optical interference type coupling / branching unit provided in each of the optical phase modulation units R1 and L1, which is not connected to the semiconductor light receiving detection circuit The phase-modulated clock signal light is output, and one of the two optical output ports P-MZ-1-cross and P-MZ-1-bar of the Mach-Zehnder interference type optical intensity modulation means MZ-1 Output signal light from one side It is characterized in that functions as a high-speed chaotic optical signal generating optical circuit obtained.

  Also, one configuration example of the optical circuit of the present invention includes an external optical input port P-OCLK-In for inputting the clock signal light CLK-1 output from the clock signal light source, and the external optical input port P-OCLK. Two optical interference arms having an optical output port P-MZ-1-bar located on the bar side with respect to In and an optical output port P-MZ-1-cross located on the cross side, and one of the lights An optical phase modulation means L1-1 for modulating the phase of an optical signal train that is positioned on the optical waveguide of the interference arm and propagates in the optical interference arm, and positioned on the optical waveguide of the other optical interference arm Mach-Zehnder interference type optical intensity having optical phase modulation means R1-1 for modulating the phase of the optical signal train propagating in the same optical interference arm and functioning as a Mach-Zehnder type interferometer It is directly or indirectly connected to the adjusting means MZ-1 and the external optical input port P-Data-In for inputting the optical signal sequence Data-1 having information to be stored, and leads the optical signal sequence Data-1. 3 optical waveguides 18 and the optical input port P-C1-1 connected to the third optical waveguide 18 to which the optical signal string Data-1 from the external optical input port P-Data-In is input, An optical output port P-C1-3 and an optical output port P-C1-3 to which an optical signal train from either the optical output port P-MZ-1-bar or the optical output port P-MZ-1-cross is input; P-C1-4, and the optical signal train input from the optical input ports P-C1-2 and P-C1-1 is branched to the optical output ports P-C1-3 and P-C1-4 Optical branching means C-1 for outputting, and A fourth optical waveguide 14 for guiding an optical signal train from either the output port P-MZ-1-bar or the optical output port P-MZ-1-cross to the optical input port P-C1-2; The optical signal train for inducing the optical phase modulation action is connected to the optical input port P-R1-1 for inputting the optical phase modulation means R1-1 to the optical output port P-C1-4. A fifth optical waveguide 15R for guiding the optical signal train and an optical input port P-L1-1 for inputting the optical signal train for inducing the optical phase modulation action to the optical phase modulator L1-1 are connected. A sixth optical waveguide 15L for guiding an optical signal train from the optical output port P-C1-3, and the sixth optical waveguide 15L or the fifth optical waveguide 15R, and the optical output port P Same as -C1-3 and P-C1-4 The timing at which the optical signal train output at times reaches the optical input ports P-L1-1 and P-R1-1 is set to be not less than the pulse width of the clock signal light CLK-1 and less than the pulse repetition period. Optical propagation delay difference providing means DD-1 for generating an optical delay for adjustment, and RZ type signal light is input from the external optical input port P-OCLK-In as the clock signal light CLK-1. When the optical signal sequence Data-1 synchronized with the clock of the clock signal light CLK-1 is input from the external optical input port P-Data-In, the input optical signal sequence is initially set. Data-1 is used to drive the optical phase modulators R1-1 and L1-1 to generate a phase difference in the clock signal light CLK-1 propagating through the two optical interference arms. By turning on or off each pulse of the clock signal light CLK-1, the optical output port P-MZ-1-bar or the optical output port P-MZ-1-cross can be used. The output optical signal sequence CLK-1-out-DMZ1 is circulated to the optical branching means C-1 as the same data pattern as the data pattern of the optical signal sequence Data-1, and the subsequent cycles are performed by the optical signal sequence CLK-1. The optical signal train CLK-1-out-DMZ1 of the previous round output from either the output port P-MZ-1-bar or the optical output port P-MZ-1-cross is used to generate the optical signal. The phase modulation means R1-1 and L1-1 are driven to cause a phase difference in the clock signal light CLK-1 propagating through the two optical interference arms, and the clock signal By turning each pulse of CLK-1 on or off, the circuit of the circuit output from one of the optical output port P-MZ-1-bar and the optical output port P-MZ-1-cross The optical signal train CLK-1-out-DMZ1 is circulated to the optical branching means C-1 as the same data pattern as the data pattern of the optical signal train Data-1, and the data pattern is maintained in the circuit. The optical phase modulation means R1-1 and L1-1 are respectively configured to receive an optical signal sequence Data-1 or an optical signal sequence CLK-1-out-DMZ1 which is an optical phase modulation control signal light, and an optical phase. A first optical interference type multiplexing / branching unit for multiplexing the clock signal light CLK-1 that is the modulated signal light and demultiplexing the combined signal light into two systems; Out of the means Two optical waveguide arms that transmit the two signal light beams that have been applied, and the two signal light signals that are transmitted by the two optical waveguide arms are combined, and the combined signal light is split into two systems. A second optical interference type merging / branching unit that performs phase modulation of the optical phase-modulated signal light according to the light intensity of the optical phase-modulation control signal light. A phase modulation control means, a phase adjustment means provided on at least one of the two optical waveguide arms and capable of adjusting the phase of the signal light in accordance with the amount of injected current supplied from the outside; An optical signal buffer comprising the semiconductor light receiving detection circuit for receiving signal light output from one of the two optical output ports of the second optical interference type branching means that is not connected to the optical interference arm. To function as a memory circuit The one in which the features.

  According to the present invention, during the initial adjustment of the optical circuit, it is possible to receive the adjustment monitor light in the signal light wavelength region by applying a reverse bias to the light receiving detector g1 and evaluate the increase or decrease in the optical power intensity. At the time of driving the optical circuit, the electrode of the light receiving detector g1 is opened or grounded to the ground so that the light receiving detector g1 is transparent to the light in the signal light wavelength region. It becomes possible to function as. In the present invention, the light receiving detection part g1 is composed of an optical waveguide structure including a lower clad layer, a core layer, and an upper clad layer, and an electrode, thereby using a light receiving layer exhibiting efficient light absorption characteristics. Therefore, it is possible to reduce the heat generated in the light receiving detection part g1 by receiving the signal light.

  Further, in the present invention, the second optical waveguide a3-out is formed so as to be coupled to the end of the light receiving detector g1 on the opposite side to the first optical waveguide a3-in, and is received by the light receiving detector g1. The signal light that does not exist is guided to the end face of the optical circuit by the second optical waveguide a3-out, and is emitted from the end face to the outside. In the present invention, since the non-reflective coating film AR-1 is formed on the end face of the optical circuit from which the signal light is emitted, the signal light that has not been received by the light receiving detector g1 is reflected on the end face of the optical circuit. It can be emitted (discarded) out of the circuit, and it is possible to suppress the signal light from being reflected and returning to the optical circuit to deteriorate the characteristics of the optical circuit.

  Further, in the present invention, the manufacturing process is performed by setting the core layer of the first optical waveguide a3-in, the core layer of the light receiving detection unit g1, and the core layer of the second optical waveguide a3-out to the same composition. It can be simplified.

  In the present invention, the first optical waveguide a3-in, the optical waveguide structure of the light receiving detector g1, and the second optical waveguide a3-out have the same composition, thereby simplifying the manufacturing process. it can.

  Further, in the present invention, by making the waveguide widths of the optical waveguide structures of the first optical waveguide a3-in and the light receiving detection portion g1 the same, the manufacturing process is facilitated and light reflection can be prevented. .

  Further, in the present invention, during the driving operation of the high-speed chaotic optical signal generation optical circuit or the optical signal buffer memory circuit, the heat generation due to the absorption of the discard signal light in the light reception detection unit g1 and the heat generation from the light reception detection unit g1 For this reason, the thermal expansion and refractive index change accompanied by local and temporal fluctuations are induced in the optical circuit, so that the balance of the optical phase modulation means of the Mach-Zehnder interference type in the optical circuit is impaired, and the optical phase It is possible to solve the problem that the desired characteristic of the modulation means is deteriorated and, consequently, the desired operation characteristic of the optical circuit including the optical phase modulation means is deteriorated.

It is a block diagram which shows the structural example of the optical phase modulation part which concerns on embodiment of this invention. It is the top view and sectional drawing of the part in which the semiconductor light reception detection circuit of the optical phase modulation part which concerns on embodiment of this invention is provided. It is a figure which shows the spectrum of the light radiate | emitted from an optical phase modulation part in embodiment of this invention. It is a block diagram explaining the structure of the conventional high-speed chaotic optical signal production | generation optical circuit. It is a schematic diagram of the optical power change of the clock signal light in the conventional high-speed chaos optical signal generation optical circuit. It is a figure which shows the input timing of the input clock signal light to the optical input port in the conventional high-speed chaotic optical signal generation optical circuit, and the input timing of the input signal light to the phase modulator. It is a figure which shows the example of the normalization optical output intensity | strength of the clock light pulse output from the optical output port in the conventional high-speed chaotic optical signal production | generation optical circuit. It is a block diagram which shows the structural example of the phase modulation part in the conventional high-speed chaotic optical signal production | generation optical circuit. It is a block diagram explaining the structure of the conventional optical signal buffer memory circuit. 10 is a timing chart of various optical signal trains in a conventional optical signal buffer memory circuit. It is a block diagram which shows the structural example of the phase modulation part in the conventional optical signal buffer memory circuit. It is the top view and sectional drawing of the part in which the light-receiving part of the phase modulation part in the conventional optical signal buffer memory circuit is provided.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. 1A, FIG. 1B, and FIG. 1C are block diagrams illustrating a configuration example of the optical phase modulation unit according to the embodiment of the present invention. FIG. 11A and FIG. ), The same components as those in FIG. 11C are denoted by the same reference numerals.

  In the following description, the configuration shown in FIGS. 1A, 1B, and 1C is used for the optical phase modulation unit R1-1 used in the optical signal buffer memory circuit shown in FIG. Although described as a configuration, the configuration of the optical phase modulation units R1-2, L1-1, and L1-2 is the same as that of the optical phase modulation unit R1-1. Although the optical waveguide and the optical input / output port are different from those in FIG. 8, the configuration shown in FIGS. 1 (A), 1 (B), and 1 (C) is the same as the high-speed chaotic optical signal shown in FIG. It can also be applied as the optical phase modulators R1 and L1 of the generation optical circuit.

  In FIGS. 1A, 1B, and 1C, a1, a2, and a4 are optical input / output ports of the optical phase modulator R1-1, and b1 and b2 are 3 dB branch type multimode interference couplers. (First and second optical interference type coupling / branching means), a5, a6, a9 and a10 are optical input / output ports of the multimode interference coupler b1, and a7, a8, a11 and a12 are optical inputs of the multimode interference coupler b2. Output ports, a3-in, a3-out, e1, e2, e3, e4, e5, e6, e7, e8 are optical waveguides, c1, c2 are optical phase modulation control units, d1, d2 are phase adjustment units, and F1 is A semiconductor light reception detection circuit, g1 is a light reception detection unit, and AR-1 is a non-reflection coating film. The optical waveguides e5 and e7 constitute one optical interference arm in the optical phase modulation unit R1-1, and the optical waveguides e6 and e8 constitute the other optical interference arm in the optical phase modulation unit R1-1.

  The optical input / output ports a1 and a2 of the optical phase modulator R1-1 are connected to the optical input / output ports a9 and a10 of the multimode interference coupler b1 via optical waveguides e1 and e2, respectively. The optical input / output ports a5 and a6 of the multimode interference coupler b1 are connected to one of the ports of the optical phase modulation controllers c1 and c2 via the optical waveguides e5 and e6, respectively. The other ports of the optical phase modulation controllers c1 and c2 are connected to optical input / output ports a7 and a8 of the multimode interference coupler b2 via optical waveguides e7 and e8, respectively. The optical input / output port a11 of the multimode interference coupler b2 is connected to the optical waveguide e3. This optical waveguide e3 is formed integrally with an optical waveguide a3-in of a semiconductor light receiving detection circuit F1 described later. The optical input / output port a12 of the multimode interference coupler b2 is connected to the optical input / output port a4 of the optical phase modulator R1-1 via the optical waveguide e4.

  1A, 1B, and 1C is used as the optical phase modulator R1-1, the optical input / output port a1 (P-R1-1 in FIG. 9) is used. ) Is connected to the optical waveguide 15R of FIG. 9, the optical input / output port a2 is connected to the optical waveguide 11R, and the optical input / output port a4 is connected to the optical waveguide 12R. 1A, 1B, and 1C is used as the optical phase modulation unit L1-1, the optical input / output port a1 (P-L1-1 in FIG. 9) is used. ) Is connected to the optical waveguide 15L, the optical input / output port a2 is connected to the optical waveguide 11L, and the optical input / output port a4 is connected to the optical waveguide 12L.

  1A, 1B, and 1C is used as the optical phase modulation unit R1-2, the optical input / output port a1 (P-R1-2 in FIG. 9) is used. ) Is connected to the optical waveguide 22R, the optical input / output port a2 is connected to the optical waveguide 13R, and the optical input / output port a4 is connected to the optical waveguide 12R. 1A, 1B, and 1C is used as the optical phase modulation unit L1-2, the optical input / output port a1 (PL-1-2 in FIG. 9) is used. ) Is connected to the optical waveguide 22L, the optical input / output port a2 is connected to the optical waveguide 13L, and the optical input / output port a4 is connected to the optical waveguide 12L.

  1A, 1B, and 1C is used as the optical phase modulation unit R1, the optical input / output port a1 is connected to the optical waveguide 101 of FIG. The optical input / output port a2 (PR1 in FIG. 4) is connected to the optical waveguide 106, and the optical input / output port a4 is connected to the optical waveguide 103. 1A, 1B, or 1C is used as the optical phase modulation unit L1, the optical input / output port a1 is connected to the optical waveguide 100, and the optical input / output is connected. The port a2 (PL1 in FIG. 4) is connected to the optical waveguide 109, and the optical input / output port a4 is connected to the optical waveguide 102.

  The phase adjustment units d1 and d2 are provided on one or both of the two optical interference arms of the optical phase modulation unit R1-1. In the configuration example of the optical phase modulation unit R1-1 illustrated in FIG. 1A, the phase adjustment unit d1 is provided in the optical waveguide e7, and another configuration example of the optical phase modulation unit R1-1 illustrated in FIG. Then, the phase adjustment unit d2 is provided in the optical waveguide e8. In another configuration example of the optical phase modulation unit R1-1 shown in FIG. 1C, the phase adjustment units d1 and d2 are provided in the optical waveguides e7 and e8, respectively. It has been.

  The optical phase modulation controllers c1 and c2 are of an optical waveguide structure having a property that the refractive index changes according to the light intensity of the optical phase modulation control signal light. The optical phase modulation controllers c1 and c2 are optical semiconductor amplifiers (SOA) having an optical waveguide structure, optical waveguide structures including quantum dot layers, or semiconductor EA modulators in a constant voltage drive state. Either.

Since the other configuration excluding the semiconductor light reception detection circuit F1 is as described with reference to FIGS.
Next, the semiconductor photodetection circuit F1 that is a feature of the present embodiment will be described. FIG. 2A is a plan view of a portion of the optical phase modulation unit R1-1 of the present embodiment where the semiconductor light receiving detection circuit F1 is provided, and FIG. 2B is a II line in FIG. 2C is a cross-sectional view taken along the line II-II in FIG. 2A, and FIG. 2D is a cross-sectional view taken along the line III-III in FIG.

  The semiconductor light reception detection circuit F1 includes an optical waveguide a3-in that guides signal light, a light reception detection unit g1 formed so as to be coupled to the optical waveguide a3-in, and light reception detection on the opposite side of the optical waveguide a3-in. An optical waveguide a3-out that is formed so as to be coupled to the end of the portion g1 and guides the signal light that has passed through the light receiving detection portion g1 to the end face of the optical circuit, and the signal light guided by the optical waveguide a3-out The non-reflective coating film AR-1 formed on the end face of the outgoing optical circuit.

  As shown in FIG. 2B, the optical waveguide a3-in is formed on the lower cladding layer Lyr-01 (compound semiconductor substrate) made of n-InP and the lower cladding layer Lyr-01. Photo Luminescence) A core layer Lyr-02 composed of InGaAsP (PL wavelength is 1.4 μm in this embodiment) having a wavelength characteristic with a wavelength shorter than the signal light wavelength λ by about 100 nm to 200 nm, and a core layer Lyr− The upper clad layer Lyr-05 made of p-InP formed on 02 and the contact layer Lyr-06 made of InGaAs formed on the upper clad layer Lyr-05. In the present embodiment, the PL wavelength of the core layer Lyr-02 is shorter than the signal light wavelength λ = 1.5 μm by about 100 nm to 200 nm, that is, the PL wavelength of the core layer Lyr-02 is 1.3 to 1.4 μm. As a result, an optical waveguide with a sufficiently small loss can be realized, and at the same time, light absorption / reception of signal light having a wavelength λ = 1.5 μm can be realized in the light receiving detection portion g1 at the time of reverse bias.

  The light reception detection part g1 has an optical waveguide structure, and is a planar substrate type optical circuit (optical phase modulation parts R1, L1, R1-1, R1-2, L1-1, L1--) in which the semiconductor light reception detection circuit F1 is used. Only when a reverse bias is applied during initial adjustment of the high-speed chaotic optical signal generation optical circuit or optical signal buffer memory circuit including 2), the signal light input from the optical waveguide a3-in is received and the light reception intensity is It can output current and functions as a transparent optical waveguide when no reverse bias is applied except during initial adjustment.

  As shown in FIG. 2C, the light receiving detector g1 includes a lower cladding layer Lyr-01 (compound semiconductor substrate), a core layer Lyr-02 formed on the lower cladding layer Lyr-01, a core An upper cladding layer Lyr-05 formed on the layer Lyr-02, a contact layer Lyr-06 formed on the upper cladding layer Lyr-05, and Au formed on the contact layer Lyr-06. Pad electrode Lyr-07. During the initial adjustment of the optical circuit, a reverse bias is applied between the pad electrode Lyr-07 and the lower cladding layer Lyr-01, and a current corresponding to the received light intensity can be taken out from the pad electrode Lyr-07.

  The optical waveguide a3-out is not absorbed when the reverse bias is applied to the light reception detection unit g1, but is not absorbed, or the light reception detection unit g1 when the reverse bias is not applied to the light reception detection unit g1. Is transmitted to the end face of the optical circuit. The cross-sectional structure of the optical waveguide a3-out is the same as that of the optical waveguide a3-in as shown in FIG.

  When the signal light guided by the optical waveguide a3-out is emitted from the end face of the optical circuit, the non-reflective coating film AR-1 suppresses reflection at the end face to become reflected return light to the optical circuit. Therefore, it is formed on the end face (including the end face of the optical waveguide a3-out) of the optical circuit from which the signal light is emitted.

  Thus, in the present embodiment, the light reception characteristic of the light reception detection unit g1 appears only when a reverse bias is applied to the light reception detection unit g1 during initial adjustment of the planar substrate type optical circuit, and no reverse bias is applied to the light reception detection unit g1. In the normal driving operation of the planar substrate type optical circuit, the light receiving detector g1 can be made to function as an optical waveguide transparent to the signal light.

  FIG. 3B shows a spectrum of light emitted from the end face of the optical phase modulation unit when the configuration shown in FIG. 1C is used as the optical phase modulation unit in which the semiconductor light receiving detection circuit F1 is used. FIG. FIG. 3B shows a light spectrum when the reverse bias applied to the light receiving detector g1 is changed in the range of 0V to −10V.

  Here, an optical spectrum analyzer generates a spectrum of light that is generated by passing current through optical phase modulation control units c1 and c2 made of SOA, propagates through the optical waveguide a3-out, and is emitted to the outside of the optical phase modulation unit. Measured with FIG. 3A shows an ASE (Amplified Sponteneous Emission) spectrum of the optical phase modulation controllers c1 and c2 (SOA). As for SOA, for example, the document “Ikuo Ogawa et al.,“ PLC hybrid integrated semiconductor optical amplifier module ”, IEICE technical report. EMD 102 (283), 7-11, 2002-08-22, The Institute of Electronics, Information and Communication Engineers ”.

  According to the actual measurement evaluation result shown in FIG. 3B, the ASE spectrum of the optical phase modulation control units c1 and c2 (SOA) in the state where the reverse bias is not applied to the light receiving detection unit g1 (reverse bias 0 V) Since the same emission light spectrum is observed, it can be confirmed that the light reception detection part g1 functions as an optical waveguide transparent to the signal light.

  Further, as the reverse bias is applied to the light receiving detector g1, the light absorption in the light receiving detector g1 expands from the short wavelength component to the long wavelength component, and the SOA of the SOA matching the signal light wavelength region of the planar substrate type optical circuit is increased. It has been experimentally confirmed that a sufficient light absorption effect can be obtained in the gain wavelength region (that is, the ASE spectral wavelength region).

  When the light reception detection unit has a termination structure as shown in Non-Patent Document 1, for example, the light reception detection unit is transparent to signal light during a normal driving operation in which a reverse bias is not applied to the light reception detection unit. Since it functions as a waveguide, the signal light is reflected at the boundary surface between the light receiving detection unit located on the extension of the incident direction of the signal light and the other region, and this signal light is mixed into the optical circuit body as reflected return light. To do. The reflected return light generated in this way acts as turbulent light for the optical circuit body, and greatly impairs the characteristics of the optical circuit.

  On the other hand, in the present embodiment, the optical waveguide a3-out is formed so as to be coupled to the end of the light reception detection part g1 on the opposite side to the optical waveguide a3-in, and is not received by the light reception detection part g1. The transmitted signal light is guided to the end face of the optical circuit by the optical waveguide a3-out, and is emitted from the end face to the outside. Furthermore, in the present embodiment, by forming the non-reflective coating film AR-1 on the end face of the optical circuit from which the signal light is emitted (end face of the optical waveguide a3-out), the signal that has not been received by the light receiving detector g1. It can be suppressed that the light is reflected from the end face of the optical circuit and is returned to the optical circuit to deteriorate the characteristics of the optical circuit.

  The structure of the semiconductor light reception detection circuit F1 is as described with reference to FIGS. 2A to 2D, but in this embodiment, the optical waveguide a3-in, the light reception detection unit g1, and the optical waveguide a3-out are included. By making the composition the same except for the pad electrode Lyr-07, the manufacturing process can be simplified.

  In this embodiment, the material of the upper cladding layer Lyr-05 is p-InP. However, when it is desired to reduce the optical loss of the upper cladding layer Lyr-05, n-InP is used as the upper cladding layer Lyr-05. Alternatively, i-InP may be used.

  Further, in the present embodiment, the waveguide widths (the vertical dimension in FIG. 2A) of the optical waveguide a3-in, the light receiving detector g1, and the optical waveguide a3-out are all made the same. This facilitates the manufacturing process and prevents light reflection. However, it is not essential that the waveguide widths are the same, and the waveguide widths of the light receiving detector g1 and the optical waveguide a3-out may be increased or decreased. Further, the light receiving detection part g1 and the optical waveguide a3-out may be a single mode waveguide or a multimode waveguide.

  In addition, the contact layer Lyr-06 is provided not only in the light receiving detection part g1, but also in the optical waveguide a3-in and the optical waveguide a3-out. The contact layer Lyr-06 of the waveguide a3-out may be eliminated.

  In the present embodiment, the material of the core layer Lyr-02 is InGaAsP. However, the material is not limited to this. InGaAs, InAlAs, InGaAlAs, InAlAsP, GaAlP, AlGaAs, AlGaAsSb, InAlGaN, InGaNAs, InGaNP, AlGaNAs, AlGaNP, AlInNAs, AlInNP, or the like may be used.

  In the example shown in FIG. 2B to FIG. 2D, the waveguide structure of the optical waveguide a3-in, the light receiving detection unit g1, and the optical waveguide a3-out is deeper than the core layer Lyr-02. Is described as a high-mesa (deep ridge) type waveguide structure, but a ridge-type waveguide structure whose mesa is shallower than the core layer Lyr-02, or a buried-type waveguide structure embedded around the ridge It doesn't matter.

  Usually, only the optical phase modulators R1, L1, R1-1, R1-2, L1-1, and L1-2 including the semiconductor light receiving detection circuit F1 are formed on the compound semiconductor substrate, and the optical phase modulators R1, The optical circuit (high-speed chaos optical signal generation optical circuit or optical signal buffer memory circuit) excluding L1, R1-1, R1-2, L1-1, and L1-2 is a quartz-based planar lightwave circuit (PLC). Circuit) or a silicon planar substrate, but the entire optical circuit may be fabricated on a compound semiconductor substrate. The silicon planar substrate is described in the document “Seiichi Itabashi,“ Research and Development Trend of Silicon Photonics ”, NTT Technical Journal, pp. 12-15, 2009.12.

  In the present embodiment, as an example of the optical circuit to which the semiconductor light reception detection circuit F1 is applied, the high-speed chaos optical signal generation optical circuit shown in FIG. 4 and the optical signal buffer memory circuit shown in FIG. 9 are given as examples. However, the present invention is not limited to this, and it is necessary to measure the power of the signal light by the semiconductor light receiving detection circuit F1 at the time of adjusting the optical circuit, and it is not necessary to measure during the normal operation of the optical circuit. The present embodiment can be applied to any optical circuit in which it is desirable to discard the signal light incident on the detection circuit F1.

  The present invention can be applied to an optical circuit.

  a1 to a12 ... optical input / output ports, b1, b2 ... multimode interference couplers, c1, c2 ... optical phase modulation control unit, d1, d2 ... phase adjustment unit, a3-in, a3-out, e1-e8 ... optical waveguide , F1... Semiconductor light reception detection circuit, g1... Light reception detection part, AR-1 ..Non-reflective coating film, Lyr-01 .. Lower cladding layer, Lyr-02... Core layer, Lyr-05. Contact layer, Lyr-07... Pad electrode, R1, L1, R1-1, R1-2, L1-1, L1-2.

Claims (8)

In a semiconductor photodetection circuit that forms part of an optical circuit through which signal light of wavelength λ propagates,
A light receiving detector g1 made of a semiconductor that absorbs at least part of the incident signal light when a reverse bias is applied and converts it into a current, and transmits the incident signal light when no reverse bias is applied;
The light receiving detector g1
An optical waveguide structure including a lower cladding layer, a core layer formed on the lower cladding layer, and an upper cladding layer formed on the core layer;
An electrode for applying the reverse bias formed on the optical waveguide structure;
The semiconductor photodetection circuit according to claim 1, wherein the PL wavelength of the core layer has a peak at a wavelength shorter by 100 to 200 nm than the wavelength λ. The semiconductor light receiving detection circuit according to claim 1,
Further, a first optical waveguide a3-in that guides the signal light to the light receiving detection unit g1,
The second optical waveguide is formed so as to be coupled to the end of the light receiving detector g1 opposite to the first optical waveguide a3-in, and guides the signal light that has passed through the light receiving detector g1 to the end face of the optical circuit. Optical waveguide a3-out;
And a non-reflective coating film AR-1 formed on the end face of the optical circuit from which the signal light guided by the second optical waveguide a3-out is emitted. The semiconductor light receiving detection circuit according to claim 2,
The semiconductor photodetection detection, wherein the core layer of the first optical waveguide a3-in, the core layer of the light receiving detection part g1, and the core layer of the second optical waveguide a3-out have the same composition. circuit. In the semiconductor light reception detection circuit according to claim 2 or 3,
The semiconductor light receiving detection circuit, wherein the first optical waveguide a3-in, the optical waveguide structure of the light receiving detection unit g1, and the second optical waveguide a3-out have the same composition. In the semiconductor light reception detection circuit according to any one of claims 2 to 4,
A semiconductor photodetection circuit according to claim 1, wherein the first optical waveguide a3-in and the optical waveguide structure of the photodetection part g1 have the same waveguide width.   An optical circuit comprising the semiconductor photodetection circuit according to any one of claims 1 to 5. The optical circuit according to claim 6, wherein
Mach-Zehnder interference type light intensity modulation means MZ-1 for inputting RZ type clock signal light;
RZ type clock signal light output from either one of the two optical output ports P-MZ-1-cross and P-MZ-1-bar of the Mach-Zehnder interference type optical intensity modulation means MZ-1 An optical demultiplexing means SP-1 for demultiplexing into the system;
The two systems of RZ type clock signal light demultiplexed by the optical demultiplexing means SP-1 are used as clock signal lights for phase modulation control to the optical phase modulation means in the Mach-Zehnder interference type optical intensity modulation means MZ-1. A third optical waveguide leading to
The Mach-Zehnder interference type light intensity modulating means MZ-1
An optical input port P-MZ-1-1 for receiving the RZ type clock signal light;
Two optical interference arms that transmit the RZ-type clock signal light input to the optical input port P-MZ-1-1;
The two optical output ports P-MZ-1-cross, P-MZ-1-bar provided at the ends of the two optical interference arms;
One RZ type clock signal light provided on each of the two optical interference arms and transmitted by the optical interference arm is phased according to the light intensity of the RZ type clock signal light input from the third optical waveguide. The optical phase modulation means R1, L1 for modulating,
The optical phase modulation means R1, L1 are
A first optical interference type multiplexing / branching unit that multiplexes the clock signal light transmitted by the optical interference arm and the clock signal light for phase modulation control, respectively, and demultiplexes the combined signal light into two systems. When,
Two optical waveguide arms for transmitting two systems of signal light output from the first optical interference type combining / branching means;
A second optical interference type multiplexing / branching unit that multiplexes two systems of signal light transmitted by the two optical waveguide arms and demultiplexes the combined signal light into two systems;
An optical phase modulation control means for phase-modulating the clock signal light provided by the two optical waveguide arms and transmitted by the optical interference arm according to the light intensity of the clock signal light for phase modulation control;
Phase adjusting means provided on at least one of the two optical waveguide arms and capable of adjusting the phase of the signal light in accordance with the amount of injected current supplied from the outside;
Of the two optical output ports of the second optical interference type merging / branching means, the semiconductor light receiving detection circuit configured to receive signal light output from the one not connected to the optical interference arm,
Further, an optical propagation delay until the two systems of RZ type clock signal lights provided in the third optical waveguide and demultiplexed by the optical demultiplexing means SP-1 reach the optical phase modulation means R1 and L1. The delay corresponding to the difference is longer in the optical propagation delay until reaching the optical phase modulation means R1 and L1 out of the two systems of RZ type clock signal light input to the optical phase modulation means R1 and L1. Optical propagation delay difference providing means DD-1 for applying to the RZ type clock signal light,
Of the two optical output ports of the second optical interference type coupling / branching unit provided in each of the optical phase modulation units R1 and L1, the phase-modulated clock from the one not connected to the semiconductor light receiving detection circuit Signal light is output, and output signal light is output from one of the two optical output ports P-MZ-1-cross and P-MZ-1-bar of the Mach-Zehnder interference type optical intensity modulation means MZ-1. An optical circuit that functions as an optical circuit for generating a high-speed chaotic optical signal. The optical circuit according to claim 6, wherein
An external optical input port P-OCLK-In for inputting the clock signal light CLK-1 output from the clock signal light source, and an optical output port located on the bar side with respect to the external optical input port P-OCLK-In Two optical interference arms having P-MZ-1-bar and an optical output port P-MZ-1-cross located on the cross side, and the optical interference arm located on the optical waveguide of one of the optical interference arms Optical phase modulation means L1-1 for modulating the phase of the optical signal train propagating through the inside, and the phase of the optical signal train propagating through the optical interference arm located on the optical waveguide of the other optical interference arm A Mach-Zehnder interference type light intensity modulation unit MZ-1 that functions as a Mach-Zehnder type interferometer,
A third optical waveguide 18 that is directly or indirectly connected to an external optical input port P-Data-In for inputting an optical signal sequence Data-1 having information to be stored and guides the optical signal sequence Data-1.
An optical input port P-C1-1 that is connected to the third optical waveguide 18 and receives an optical signal string Data-1 from the external optical input port P-Data-In, and the optical output port P-MZ- 1-bar or P-C1-2 to which an optical signal train from one of the optical output ports P-MZ-1-cross is input, and optical output ports P-C1-3, P-C1-4 Optical branching means for branching and outputting the optical signal train input from the optical input ports P-C1-2 and P-C1-1 to the optical output ports P-C1-3 and P-C1-4 C-1,
A fourth optical waveguide that guides an optical signal train from either the optical output port P-MZ-1-bar or the optical output port P-MZ-1-cross to the optical input port P-C1-2. 14 and
The light from the optical output port P-C1-4 connected to the optical input port P-R1-1 for inputting the optical signal sequence for inducing the optical phase modulation action to the optical phase modulation means R1-1. A fifth optical waveguide 15R for guiding the signal train;
Light from the optical output port P-C1-3 connected to the optical input port P-L1-1 for inputting the optical signal sequence for inducing the optical phase modulation action to the optical phase modulation means L1-1. A sixth optical waveguide 15L for guiding the signal train;
An optical signal sequence provided on the sixth optical waveguide 15L or the fifth optical waveguide 15R and simultaneously output from the optical output ports P-C1-3 and P-C1-4 is the optical input port P-. Light propagation delay difference providing means for generating an optical delay for adjusting the timing to reach L1-1 and P-R1-1 so as to be not less than the pulse width of the clock signal light CLK-1 and less than the pulse repetition period. D-D-1 and
As the clock signal light CLK-1, RZ type signal light is inputted from the external light input port P-OCLK-In,
When the optical signal string Data-1 synchronized with the clock of the clock signal light CLK-1 is input from the external optical input port P-Data-In, first, the input optical signal string Data-1 is changed. The optical phase modulation means R1-1 and L1-1 are driven to cause a phase difference in the clock signal light CLK-1 propagating through the two optical interference arms, and the clock signal An optical signal sequence output from either the optical output port P-MZ-1-bar or the optical output port P-MZ-1-cross by turning on or off each pulse of the optical CLK-1. CLK-1-out-DMZ1 is circulated to the optical branching means C-1 as the same data pattern as the data pattern of the optical signal sequence Data-1,
Subsequent rounds are the previous rounds of the optical signal train CLK-1-out- output from either the optical output port P-MZ-1-bar or the optical output port P-MZ-1-cross. Using DMZ1, the optical phase modulation means R1-1 and L1-1 are driven to cause a phase difference in the clock signal light CLK-1 propagating through the two optical interference arms, and By turning on or off each pulse of the clock signal light CLK-1, the light output port P-MZ-1-bar or the light output port P-MZ-1-cross is output from the one. The circulating optical signal sequence CLK-1-out-DMZ1 is circulated to the optical branching means C-1 as the same data pattern as the data pattern of the optical signal sequence Data-1, and the data The turn be configured to maintain in the circuit,
The optical phase modulation means R1-1 and L1-1 are
The optical signal sequence Data-1 or the optical signal sequence CLK-1-out-DMZ1 that is the optical phase modulation control signal light and the clock signal light CLK-1 that is the optical phase modulation signal light are combined and combined. First optical interference type branching and splitting means for branching the signal light into two systems;
Two optical waveguide arms for transmitting two systems of signal light output from the first optical interference type combining / branching means;
A second optical interference type multiplexing / branching unit that multiplexes two systems of signal light transmitted by the two optical waveguide arms and demultiplexes the combined signal light into two systems;
Optical phase modulation control means provided on the two optical waveguide arms one by one, and phase-modulating the light phase modulation signal light in accordance with the light intensity of the optical phase modulation control signal light;
Phase adjusting means provided on at least one of the two optical waveguide arms and capable of adjusting the phase of the signal light in accordance with the amount of injected current supplied from the outside;
Of the two optical output ports of the second optical interference type merging / branching means, the semiconductor light receiving detection circuit configured to receive signal light output from the one not connected to the optical interference arm,
An optical circuit which functions as an optical signal buffer memory circuit.