WO2022249283A1 - 半導体光位相変調器及びその検査方法 - Google Patents
半導体光位相変調器及びその検査方法 Download PDFInfo
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- WO2022249283A1 WO2022249283A1 PCT/JP2021/019813 JP2021019813W WO2022249283A1 WO 2022249283 A1 WO2022249283 A1 WO 2022249283A1 JP 2021019813 W JP2021019813 W JP 2021019813W WO 2022249283 A1 WO2022249283 A1 WO 2022249283A1
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- semiconductor optical
- optical amplifier
- optical
- semiconductor
- phase modulator
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference
- G02F1/225—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference in an optical waveguide structure
- G02F1/2257—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference in an optical waveguide structure the optical waveguides being made of semiconducting material
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/015—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction
- G02F1/025—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction in an optical waveguide structure
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference
- G02F1/212—Mach-Zehnder type
Definitions
- the present disclosure relates to a semiconductor optical phase modulator and an inspection method thereof.
- Patent Document 1 discloses an optical phase modulator.
- the optical phase modulator comprises a QPSK phase modulator, a first semiconductor optical amplifier arranged at the input of the QPSK phase modulator, and a second semiconductor optical amplifier arranged at the output of the QPSK phase modulator. ing.
- An optical input end of the optical phase modulator is optically coupled to an input optical fiber for inputting light into the optical phase modulator.
- An optical output end of the optical phase modulator is optically coupled to an output optical fiber for transmitting modulated signal light generated by the optical phase modulator.
- an input passive waveguide is formed between the optical input terminal of the optical phase modulator and the first semiconductor optical amplifier, and the optical phase modulator
- An output passive waveguide is formed between the optical output end and the second semiconductor optical amplifier.
- the optical confinement factor of each of the input passive waveguide and the output passive waveguide is greater than the optical confinement factor of the first semiconductor optical amplifier and greater than the optical confinement factor of the second semiconductor optical amplifier. Since the mode field diameter of light in each of the input passive waveguide and the output passive waveguide is small, the optical coupling loss between the optical phase modulator and the input optical fiber and between the optical phase modulator and the output optical fiber has a large optical coupling loss.
- the inspection of the optical phase modulator disclosed in Patent Document 1 is performed by the following method.
- An inspection light source and an input optical fiber are arranged at the optical input end of the optical phase modulator.
- An output optical fiber and a power meter are arranged at the optical output end of the optical phase modulator.
- Light emitted from a light source enters an optical phase modulator through an input optical fiber.
- the light output from the optical phase modulator is made incident on the power meter through the output optical fiber. If the output of the power meter is equal to or higher than the reference output, the optical phase modulator is determined to be non-defective. On the other hand, if the output of the power meter is less than the reference output, the optical phase modulator is determined to be defective.
- An object of the first aspect of the present disclosure is to provide a semiconductor optical phase modulator capable of reducing optical coupling loss with an optical fiber.
- An object of a second aspect of the present disclosure is to provide an inspection method for a semiconductor optical phase modulator capable of shortening the inspection time of the semiconductor optical phase modulator.
- a semiconductor optical phase modulator of the present disclosure includes an optical phase modulation element, a first semiconductor optical amplifier that amplifies light input to the optical phase modulation element, and a first semiconductor optical amplifier that amplifies modulated signal light output from the optical phase modulation element. and two semiconductor optical amplifiers.
- a first semiconductor optical amplifier includes a first core layer having a first multiple quantum well structure.
- the optical phase modulation element includes a second core layer having a second multiple quantum well structure.
- a second semiconductor optical amplifier includes a third core layer having a third multiple quantum well structure.
- the first thickness of the first core layer is less than the second thickness of the second core layer.
- the number of first well layers in the first multiple quantum well structure is less than the number of second well layers in the second multiple quantum well structure.
- the third thickness of the third core layer is less than the second thickness of the second core layer.
- the number of third well layers in the third multiple quantum well structure is smaller than the number of second well layers in the second multiple quantum well structure.
- the optical input end of the semiconductor optical phase modulator is the optical input end face of the first semiconductor optical amplifier.
- the optical output end of the semiconductor optical phase modulator is the optical output end face of the second semiconductor optical amplifier.
- a semiconductor optical phase modulator inspection method applies a forward bias voltage to one of the first semiconductor optical amplifier and the second semiconductor optical amplifier, and inspects the semiconductor optical phase modulator from one of the first semiconductor optical amplifier and the second semiconductor optical amplifier. emitting light; applying a reverse bias voltage to the other of the first semiconductor optical amplifier and the second semiconductor optical amplifier; Comparing the intensity and a reference light intensity.
- the optical confinement factor of the first semiconductor optical amplifier is smaller than the optical confinement factor of the optical phase modulation element
- the optical confinement factor of the second semiconductor optical amplifier is smaller than the optical confinement factor of the optical phase modulation element.
- the mode field diameter of light in each of the first semiconductor optical amplifier and the second semiconductor optical amplifier increases.
- the optical coupling loss between the semiconductor optical phase modulator and the input optical fiber and the optical coupling loss between the semiconductor optical phase modulator and the output optical fiber can be reduced.
- the inspection method of the semiconductor optical phase modulator of the present disclosure there is no need to prepare an inspection light source, an input optical fiber, an output optical fiber, and a power meter separately from the semiconductor optical phase modulator. There is no need to align the inspection light source, the input optical fiber, the output optical fiber and the power meter with respect to the instrument. Therefore, according to the inspection method of the semiconductor optical phase modulator of the present disclosure, the inspection time of the semiconductor optical phase modulator can be shortened.
- FIG. 2 is a schematic plan view of the semiconductor optical phase modulator of Embodiment 1;
- FIG. 2 is a schematic cross-sectional view of a passive waveguide of the semiconductor optical phase modulator of Embodiment 1;
- FIG. 2 is a schematic cross-sectional view of an optical splitter and an optical coupler of the semiconductor optical phase modulator of Embodiment 1;
- FIG. 3A and 3B are schematic cross-sectional views of a phase modulation section and a phase adjustment section of the semiconductor optical phase modulator of Embodiment 1;
- 2 is a schematic cross-sectional view of a first semiconductor optical amplifier of the semiconductor optical phase modulator of Embodiment 1;
- FIG. 4 is a schematic cross-sectional view of a second semiconductor optical amplifier of the semiconductor optical phase modulator of Embodiment 1;
- FIG. 2 is a control block diagram of the semiconductor optical phase modulation device of Embodiment 1.
- FIG. 4 is a diagram showing a flowchart of an inspection method for the semiconductor optical phase modulator according to the first embodiment;
- FIG. FIG. 8 is a schematic plan view of a semiconductor optical phase modulator according to a second embodiment; 8 is a schematic cross-sectional view of a monitor photodiode of the semiconductor optical phase modulator of Embodiment 2;
- FIG. 8 is a schematic cross-sectional view of a monitor photodiode of the semiconductor optical phase modulator of Embodiment 2;
- FIG. 10 is a diagram showing a flowchart of an inspection method for a semiconductor optical phase modulator according to a second embodiment
- FIG. 11 is a schematic plan view of a semiconductor optical phase modulator according to Embodiment 3
- 11 is a schematic cross-sectional view of a third semiconductor optical amplifier of the semiconductor optical phase modulator of Embodiment 3
- FIG. 11 is a diagram showing a flowchart of a method for inspecting a semiconductor optical phase modulator according to Embodiment 3;
- Embodiment 1 A semiconductor optical phase modulator 1 according to a first embodiment will be described with reference to FIGS. 1 to 6.
- FIG. The semiconductor optical phase modulator 1 mainly includes an optical phase modulation element 3 , a first semiconductor optical amplifier 40 , a second semiconductor optical amplifier 50 and a substrate 9 .
- the substrate 9 is, for example, a semiconductor substrate such as an InP substrate.
- the substrate 9 includes a first end surface 9a and a second end surface 9b.
- the second end face 9b may be on the opposite side of the first end face 9a.
- the optical phase modulation element 3 , the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 are formed on the substrate 9 .
- the optical phase modulation element 3 is, for example, an IQ (In-phase Quadrature) optical modulation section capable of quadrature phase shift keying (QPSK).
- the optical phase modulation element 3 includes a parent Mach-Zehnder interferometer 10, two child Mach-Zehnder interferometers 20, phase modulation sections 25 and 26, parent phase adjustment sections 17 and 18, and child phase adjustment sections 27 and 28. .
- the parent Mach-Zehnder interferometer 10, the two child Mach-Zehnder interferometers 20, the phase modulation sections 25 and 26, the parent phase adjustment sections 17 and 18, and the child phase adjustment sections 27 and 28 have common materials and layer structures.
- a core layer core layers 32, 42, 52 may be included.
- the parent Mach-Zehnder interferometer 10 includes two first arm waveguides 11 and 12, an optical splitter 13, and an optical coupler 14.
- the first arm waveguides 11 and 12 each include a lower clad layer 31, a core layer 32, and an upper clad layer 33.
- the first arm waveguides 11 , 12 may further include an insulating protective layer 37 .
- the lower clad layer 31 is formed on the substrate 9 .
- the lower clad layer 31 is, for example, an n-type InP layer.
- a core layer 32 is formed on the lower clad layer 31 .
- the core layer 32 has a refractive index higher than that of the lower clad layer 31 and higher than that of the upper clad layer 33 .
- the core layer 32 is made of a semiconductor material such as AlGaInAs, for example.
- the core layer 32 has, for example, a multiple quantum well (MQW) structure.
- the upper clad layer 33 is formed on the core layer 32 .
- the upper clad layer 33 is, for example, an i-type InP layer.
- the first arm waveguides 11 and 12 each have a high mesa structure.
- An insulating protective layer 37 is formed on the high mesa structure. Specifically, the insulating protective layer 37 is formed on the top and side surfaces of the upper clad layer 33 , the side surfaces of the core layer 32 , and the lower clad layer 31 .
- the insulating protective layer 37 is made of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as benzocyclobutene (BCB).
- BCB benzocyclobutene
- the optical splitter 13 is formed between the two first arm waveguides 11 and 12 and the first semiconductor optical amplifier 40 .
- the optical splitter 13 splits the light amplified by the first semiconductor optical amplifier 40 and outputs it to the two first arm waveguides 11 and 12 .
- the optical splitter 13 includes a lower clad layer 31, a core layer 32 and an upper clad layer 33, similar to the first arm waveguides 11,12.
- the optical splitter 13 is made of the same material as the first arm waveguides 11 and 12 and has the same layer structure.
- Optical splitter 13 is, for example, a multimode interference (MMI) splitter.
- the optical splitter 13 is, for example, a 2 ⁇ 2 MMI splitter.
- the width of the core layer 32 of the optical splitter 13 is larger than the width of each core layer 32 of the two first arm waveguides 11 and 12 .
- Two output ports of the optical splitter 13 are connected to the two first arm waveguides 11 and 12 .
- One of the two input ports of optical splitter 13 is optically coupled to first semiconductor optical amplifier 40 .
- the optical waveguide 39 is connected to one of the two input ports of the optical splitter 13 and the first semiconductor optical amplifier 40 .
- the optical waveguide 39 has the same configuration as each of the first arm waveguides 11 and 12 .
- the optical coupler 14 is formed between the two first arm waveguides 11 and 12 and the second semiconductor optical amplifier 50 .
- the optical coupler 14 multiplexes the light propagating through the two first arm waveguides 11 and 12 and outputs the combined light toward the second semiconductor optical amplifier 50 .
- the optical coupler 14 is constructed similarly to the optical splitter 13 .
- the optical coupler 14 is made of the same material as the optical splitter 13 and the second arm waveguide, and has the same layer structure.
- the optical coupler 14 is, for example, an MMI coupler.
- Optical coupler 14 is, for example, a 2 ⁇ 2 MMI coupler.
- the width of the core layer 32 of the optical coupler 14 is larger than the width of each core layer 32 of the two first arm waveguides 11 and 12 .
- Two input ports of the optical coupler 14 are connected to the two first arm waveguides 11 and 12 .
- One of the two output ports of optical coupler 14 is optically coupled to second semiconductor optical amplifier 50 .
- the optical waveguide 49 is connected to one of the two output ports of the optical coupler 14 and the second semiconductor optical amplifier 50 .
- the optical waveguide 49 has the same configuration as each of the first arm waveguides 11 and 12 .
- the two child Mach-Zehnder interferometers 20 are connected to the two first arm waveguides 11 and 12, respectively.
- the child Mach-Zehnder interferometer 20 and the phase modulation units 25 and 26 connected to the first arm waveguide 11 constitute, for example, a Mach-Zehnder type optical phase modulator for the I channel.
- the secondary Mach-Zehnder interferometer 20 and the phase modulators 25 and 26 connected to the first arm waveguide 12 constitute, for example, a Q-channel Mach-Zehnder optical phase modulator.
- Each child Mach-Zehnder interferometer 20 includes two second arm waveguides 21, 22, an optical splitter 23, and an optical coupler 24. FIG.
- the second arm waveguides 21 and 22 each have the same configuration as the first arm waveguides 11 and 12 respectively.
- the second arm waveguides 21 and 22 are made of the same material as the first arm waveguides 11 and 12 and have the same layer structure.
- the optical splitter 23 is formed between the two second arm waveguides 21 and 22 and the optical splitter 13 .
- the optical splitter 23 further splits the light split by the optical splitter 13 and outputs the split light to the two second arm waveguides 21 and 22 .
- optical splitter 23 is configured similarly to optical splitter 13 .
- the optical splitter 23 is, for example, an MMI splitter.
- the optical splitter 23 is, for example, a 2 ⁇ 2 MMI splitter.
- Two output ports of the optical splitter 23 are connected to the two second arm waveguides 21 and 22 .
- One of the two input ports of the optical splitter 23 is connected to one of the two first arm waveguides 11,12.
- the optical coupler 24 is formed between the two second arm waveguides 21 and 22 and the optical coupler 14 .
- the optical coupler 24 multiplexes the light propagating through the two second arm waveguides 21 and 22 and outputs the combined light toward the optical coupler 14 .
- optical coupler 24 is configured similarly to optical coupler 14 .
- the optical coupler 24 is, for example, an MMI coupler.
- Optical coupler 24 is, for example, a 2 ⁇ 2 MMI coupler.
- Two input ports of the optical coupler 24 are connected to the two second arm waveguides 21 and 22 .
- One of the two output ports of the optical coupler 24 is connected to one of the two first arm waveguides 11,12.
- the phase modulating sections 25 and 26 are provided on the two second arm waveguides 21 and 22 .
- the phase modulating section 25 is provided in the second arm waveguide 21 .
- the phase modulating section 26 is provided in the second arm waveguide 22 .
- the phase modulation sections 25 and 26 each include a contact layer 34 and an electrode 36 in addition to the lower clad layer 31, core layer 32 and upper clad layer 33b.
- the phase modulating sections 25 and 26 may further include an insulating protective layer 37 .
- the upper clad layer 33b of the phase modulating sections 25 and 26 is, for example, a p-type InP layer.
- the contact layer 34 is, for example, a p-type InGaAs layer, AuZn layer or AuBe layer.
- the electrodes 36 are made of metal such as Ti, Au, Pt, Nb or Ni, for example.
- the phase modulating sections 25 and 26 have, for example, a high mesa structure.
- An insulating protective layer 37 is formed on the high mesa structure. Specifically, the insulating protective layer 37 is formed on the side surface of the contact layer 34 , the side surface of the upper clad layer 33 b , the side surface of the core layer 32 , and the lower clad layer 31 .
- the parent phase adjusters 17 and 18 are provided on the two first arm waveguides 11 and 12 .
- the parent phase adjuster 17 is provided in the first arm waveguide 11 .
- the parent phase adjuster 18 is provided in the first arm waveguide 12 .
- the parent phase adjusters 17 and 18 have the same configuration as the phase modulators 25 and 26 .
- the parent phase adjustment sections 17 and 18 are made of the same material as the phase modulation sections 25 and 26 and have the same layer structure.
- the phase difference between the I-channel optical signal output from the first arm waveguide 11 and the Q-channel optical signal output from the first arm waveguide 12 at the input port of the optical coupler 14 is ⁇ /2.
- the phases applied to the I-channel optical signal and the Q-channel optical signal are adjusted in the parent phase adjusters 17 and 18, respectively.
- the child phase adjusters 27 and 28 are provided on the two second arm waveguides 21 and 22 . Specifically, the child phase adjustment section 27 is provided in the second arm waveguide 21 . The child phase adjustment section 28 is provided in the second arm waveguide 22 . As shown in FIG. 4, child phase adjusters 27 and 28 have the same configuration as phase modulating sections 25 and 26 . The child phase adjustment sections 27 and 28 are made of the same material as the phase modulation sections 25 and 26 and have the same layer structure.
- the first semiconductor optical amplifier 40 is formed between the optical phase modulation element 3 and the first end face 9a of the substrate 9.
- the optical input end of the semiconductor optical phase modulator 1 is the optical input end surface 40 a of the first semiconductor optical amplifier 40 .
- a first semiconductor optical amplifier 40 is optically coupled to the input optical fiber 5a.
- the light input end face 40 a of the first semiconductor optical amplifier 40 may be flush with the first end face 9 a of the substrate 9 .
- the first semiconductor optical amplifier 40 amplifies light input to the optical phase modulation element 3 .
- the first semiconductor optical amplifier 40 includes a lower clad layer 41, a core layer 42, an upper clad layer 43, a current blocking layer 45, contact layers 44a and 44b, and electrodes 46a and 46b. including.
- the first semiconductor optical amplifier 40 may further include an insulating protective layer 37 .
- a lower clad layer 41 is formed on the substrate 9 .
- the lower clad layer 41 is, for example, an n-type InP layer.
- a core layer 42 is formed on the lower clad layer 41 .
- the core layer 42 has a refractive index higher than that of the lower clad layer 41 and higher than that of the upper clad layer 43 .
- the core layer 42 is made of a semiconductor material such as AlGaInAs, for example.
- the core layer 42 has, for example, a multiple quantum well (MQW) structure.
- the thickness of the core layer 42 of the first semiconductor optical amplifier 40 is smaller than the thickness of the core layer 32 of the optical phase modulation element 3 .
- the number of well layers in the core layer 42 of the first semiconductor optical amplifier 40 is smaller than the number of well layers in the core layer 32 of the optical phase modulation element 3 . Therefore, the optical confinement factor of the first semiconductor optical amplifier 40 is smaller than the optical confinement factor of the optical phase modulation element 3 .
- the upper clad layer 43 is, for example, a p-type InP layer.
- the first semiconductor optical amplifier 40 has, for example, a high mesa structure.
- the current blocking layers 45 are formed on both side surfaces of the core layer 42 .
- the current blocking layer 45 concentrates the current flowing between the electrodes 46a and 46b to the core layer 42.
- the current blocking layer 45 includes, for example, a p-type semiconductor layer 45a such as p-type InP and an n-type semiconductor layer 45b such as n-type InP.
- the current blocking layer 45 may be a semi-insulating layer such as an Fe-doped InP layer.
- the contact layers 44a and 44b are, for example, n-type InGaAs layers, AuZn layers or AuBe layers.
- the electrodes 46a, 46b are made of metal such as Ti, Au, Pt, Nb or Ni, for example.
- An insulating protective layer 37 is formed on the high mesa structure. Specifically, the insulating protective layer 37 is formed on the contact layers 44 a and 44 b , the side surfaces of the upper clad layer 43 , the side surface of the current blocking layer 45 and the lower clad layer 41 .
- the second semiconductor optical amplifier 50 is formed between the optical phase modulation element 3 and the second end face 9b of the substrate 9.
- the optical output end of the semiconductor optical phase modulator 1 is the optical output end surface 50 a of the second semiconductor optical amplifier 50 .
- a second semiconductor optical amplifier 50 is optically coupled to the output optical fiber 5b.
- the light output end face 50 a of the second semiconductor optical amplifier 50 may be flush with the second end face 9 b of the substrate 9 .
- the second semiconductor optical amplifier 50 amplifies the modulated signal light output from the optical phase modulation element 3 .
- the second semiconductor optical amplifier 50 is configured similarly to the first semiconductor optical amplifier 40 .
- the second semiconductor optical amplifier 50 includes a lower clad layer 51, a core layer 52, an upper clad layer 53, a current blocking layer 55, and contact layers 54a and 54b. , electrodes 56a and 56b.
- the current blocking layer 55 includes, for example, a p-type semiconductor layer 55a such as p-type InP and an n-type semiconductor layer 55b such as n-type InP.
- the current blocking layer 55 may be a semi-insulating layer such as an Fe-doped InP layer.
- the second semiconductor optical amplifier 50 may further include an insulating protective layer 37 .
- the core layer 42 of the first semiconductor optical amplifier 40 and the core layer 52 of the second semiconductor optical amplifier 50 are made of the same material and may have the same layer structure.
- the thickness of the core layer 52 of the second semiconductor optical amplifier 50 is smaller than the thickness of the core layer 32 of the optical phase modulation element 3 .
- the number of well layers in the core layer 52 of the second semiconductor optical amplifier 50 is smaller than the number of well layers in the core layer 32 of the optical phase modulation element 3 . Therefore, the optical confinement factor of the core layer 52 of the second semiconductor optical amplifier 50 is smaller than the optical confinement factor of the core layer 32 of the optical phase modulation element 3 .
- the second length of the second semiconductor optical amplifier 50 may be shorter than the first length of the first semiconductor optical amplifier 40 .
- the first length of the first semiconductor optical amplifier 40 means the length between the light input end surface 40a of the first semiconductor optical amplifier 40 and the light output end surface of the first semiconductor optical amplifier 40
- the second length of the second semiconductor optical amplifier 50 means the length between the light input end face of the second semiconductor optical amplifier 50 and the light output end face 50 a of the second semiconductor optical amplifier 50 .
- the carrier density in the semiconductor optical amplifier fluctuates depending on the intensity distribution of light incident on the semiconductor optical amplifier.
- the intensity distribution of light entering the semiconductor optical amplifier means the intensity distribution of the light in a cross section perpendicular to the traveling direction of the light. Fluctuations in carrier density within the semiconductor optical amplifier cause variations in the refractive index within the semiconductor optical amplifier, causing phase distortion in the light amplified by the semiconductor optical amplifier.
- optical phase modulation device 2 includes semiconductor optical phase modulator 1 and controller 7 .
- Semiconductor optical phase modulator 1 is connected to controller 7 .
- the controller 7 applies voltages to the phase modulation sections 25 and 26, voltages applied to the parent phase adjustment sections 17 and 18, voltages applied to the child phase adjustment sections 27 and 28, and injection to the first semiconductor optical amplifier 40.
- the current to be applied, the current to be injected into the second semiconductor optical amplifier 50, the voltage to be applied to the first semiconductor optical amplifier 40, and the voltage to be applied to the second semiconductor optical amplifier 50 can be controlled.
- the controller 7 compares the intensity of the inspection light detected by the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 with the reference light intensity to determine whether the semiconductor optical phase modulator 1 is non-defective. can determine whether Controller 7 is, for example, a microcomputer or electronic circuit including a processor.
- the operation of the semiconductor optical phase modulator 1 of this embodiment will be described.
- the first semiconductor optical amplifier 40 amplifies light input to the semiconductor optical phase modulator 1 .
- a high-frequency electrical signal is applied to the phase modulating portions 25 and 26 to change the refractive index of the core layer 32 of the phase modulating portions 25 and 26 .
- a secondary Mach-Zehnder interferometer 20 connected to the first arm waveguide 11 outputs an I-channel optical signal.
- a child Mach-Zehnder interferometer 20 connected to the first arm waveguide 12 outputs a Q-channel optical signal.
- the optical coupler 14 multiplexes the I-channel optical signal and the Q-channel optical signal.
- the optical phase modulation element 3 outputs modulated signal light toward the second semiconductor optical amplifier 50 .
- the second semiconductor optical amplifier 50 amplifies the modulated signal light.
- the semiconductor optical phase modulator 1 outputs modulated signal light.
- the inspection method of the semiconductor optical phase modulator 1 of the present embodiment consists of radiating inspection light from one of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 (S1), applying a reverse bias voltage to the other of the second semiconductor optical amplifiers 50 (S2), the intensity of the inspection light detected by the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50, and the reference light intensity; and (S5).
- the inspection method of the semiconductor optical phase modulator 1 according to the present embodiment includes the child phase adjusters. It further comprises adjusting the voltage applied to the units 27 and 28 (S3) and adjusting the voltage applied to the parent phase adjustment units 17 and 18 (S4).
- step S1 a forward bias voltage is applied to one of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50, for example.
- One of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 emits amplified spontaneous emission light (ASE light). This ASE light is used as inspection light, and one of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 functions as a light source for the inspection light.
- ASE light amplified spontaneous emission light
- step S2 a reverse bias voltage is applied to the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50.
- the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 functions as a photodiode that detects the intensity of inspection light. Either step S2 or step S1 may be performed first.
- step S3 the voltage applied to the child phase adjusters 27 and 28 is adjusted.
- the controller 7 adjusts the voltage applied to the child phase adjusters 27 and 28 so that the intensity of the inspection light detected by the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 is maximized. .
- step S4 the voltage applied to the parent phase adjusters 17 and 18 is adjusted.
- the controller 7 adjusts the voltage applied to the parent phase adjusters 17 and 18 so that the intensity of the inspection light detected by the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 is maximized.
- Steps S3 and S4 may be performed repeatedly.
- step S5 the controller 7 compares the intensity of the inspection light detected by the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 with the reference light intensity. For example, when the intensity of the inspection light is greater than or equal to the reference light intensity, the controller 7 determines that the semiconductor optical phase modulator 1 is non-defective. On the other hand, when the intensity of the inspection light is less than the reference light intensity, the controller 7 determines that the semiconductor optical phase modulator 1 is defective.
- the semiconductor optical phase modulator 1 of the present embodiment includes the optical phase modulation element 3, the first semiconductor optical amplifier 40 that amplifies the light input to the optical phase modulation element 3, and the light output from the optical phase modulation element 3. and a second semiconductor optical amplifier 50 for amplifying the modulated signal light.
- the first semiconductor optical amplifier 40 includes a first core layer (core layer 42) having a first multiple quantum well structure.
- the optical phase modulation element 3 includes a second core layer (core layer 32) having a second multiple quantum well structure.
- the second semiconductor optical amplifier 50 includes a third core layer (core layer 52) having a third multiple quantum well structure.
- the first thickness of the first core layer is less than the second thickness of the second core layer.
- the number of first well layers in the first multiple quantum well structure is less than the number of second well layers in the second multiple quantum well structure.
- the third thickness of the third core layer is less than the second thickness of the second core layer.
- the number of third well layers in the third multiple quantum well structure is smaller than the number of second well layers in the second multiple quantum well structure.
- the optical input end of the semiconductor optical phase modulator 1 is the optical input end surface 40 a of the first semiconductor optical amplifier 40 .
- the optical output end of the semiconductor optical phase modulator 1 is the optical output end surface 50 a of the second semiconductor optical amplifier 50 .
- the optical confinement factor of the first semiconductor optical amplifier 40 is smaller than the optical confinement factor of the optical phase modulation element 3
- the optical confinement factor of the second semiconductor optical amplifier 50 is smaller than the optical confinement factor of the optical phase modulation element 3. small.
- the mode field diameter of light in each of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 increases.
- the optical coupling loss between the semiconductor optical phase modulator 1 and the input optical fiber 5a and the optical coupling loss between the semiconductor optical phase modulator 1 and the output optical fiber 5b can be reduced.
- the semiconductor optical phase modulator 1 of this embodiment further includes a substrate 9 on which the optical phase modulation element 3, the first semiconductor optical amplifier 40, and the second semiconductor optical amplifier 50 are mounted.
- the light input end face 40 a of the first semiconductor optical amplifier 40 is flush with the first end face 9 a of the substrate 9 .
- the light output end face 50a of the second semiconductor optical amplifier 50 is flush with the second end face 9b of the substrate 9, which is different from the first end face 9a. Therefore, the optical coupling loss between the semiconductor optical phase modulator 1 and the input optical fiber 5a and the optical coupling loss between the semiconductor optical phase modulator 1 and the output optical fiber 5b can be reduced.
- the second length of the second semiconductor optical amplifier 50 is shorter than the first length of the first semiconductor optical amplifier 40 . Therefore, the phase distortion that the second semiconductor optical amplifier 50 gives to the modulated signal light output from the optical phase modulation element 3 can be reduced.
- the semiconductor optical phase modulator 1 can output phase-modulated signal light of higher quality.
- the first core layer (core layer 42) and the third core layer (core layer 52) are made of the same material and have the same layer structure. have. Therefore, the core layer of the semiconductor optical phase modulator 1 is made of two kinds of core materials. Since the types of core layers of the semiconductor optical phase modulator 1 are reduced, the cost of the semiconductor optical phase modulator 1 can be reduced.
- the optical phase modulation element 3 includes a parent Mach-Zehnder interferometer 10, two child Mach-Zehnder interferometers 20, and phase modulation sections 25 and 26.
- the parent Mach-Zehnder interferometer 10 includes two first arm waveguides 11,12.
- the two child Mach-Zehnder interferometers 20 are connected to the two first arm waveguides 11 and 12 respectively, and the two child Mach-Zehnder interferometers 20 are each connected to the two second arm waveguides 21 , 22.
- the phase modulating sections 25 and 26 are provided on the two second arm waveguides 21 and 22, respectively. Therefore, the semiconductor optical phase modulator 1 can output a multilevel phase modulated signal such as QPSK.
- the optical phase modulation element 3 further includes parent phase adjusters 17 and 18 and child phase adjusters 27 and 28 .
- the parent phase adjusters 17 and 18 are provided on the two first arm waveguides 11 and 12 .
- the secondary phase adjusting sections 27 and 28 are provided on the two second arm waveguides 21 and 22 . Therefore, the semiconductor optical phase modulator 1 can output a higher quality multilevel phase modulated signal.
- a forward bias voltage is applied to one of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50, and the first semiconductor optical amplifier 40 and the second semiconductor emitting inspection light from one of the optical amplifiers 50 (S1); applying a reverse bias voltage to the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 (S2); 40 and comparing the intensity of the inspection light detected by the other of the second semiconductor optical amplifier 50 with the reference light intensity (S5).
- the inspection method of the semiconductor optical phase modulator 1 of the present embodiment there is no need to prepare an inspection light source, an input optical fiber, an output optical fiber, and a power meter separately from the semiconductor optical phase modulator 1. It is not necessary to align the inspection light source, the input optical fiber, the output optical fiber, and the power meter with respect to the semiconductor optical phase modulator 1 . Therefore, the inspection time of the semiconductor optical phase modulator 1 can be shortened.
- Embodiment 2 A semiconductor optical phase modulator 1b according to a second embodiment will be described with reference to FIGS. 9 to 12.
- FIG. The semiconductor optical phase modulator 1b of the present embodiment has the same configuration as the semiconductor optical phase modulator 1 of the first embodiment, but differs mainly in the following points.
- the semiconductor optical phase modulator 1b further includes a monitor photodiode 60 and a monitor photodiode .
- a monitor photodiode 60 is optically coupled to the other of the two output ports of the optical coupler 14 .
- a monitoring photodiode 70 is optically coupled to the other of the two output ports of the optical coupler 24 .
- a monitor photodiode 60 includes a lower clad layer 61, a light absorption layer 62, an upper clad layer 63, contact layers 64a and 64b, and electrodes 66a and 66b.
- the monitor photodiode 60 may further include an insulating protective layer 37 .
- a lower clad layer 61 is formed on the substrate 9 .
- the lower clad layer 61 is, for example, an n-type InP layer.
- the refractive index of the light absorption layer 62 is higher than the refractive index of the lower clad layer 61 and higher than the refractive index of the upper clad layer 63 .
- the light absorbing layer 62 is made of a semiconductor material such as AlGaInAs, for example.
- the light absorption layer 62 has, for example, a multiple quantum well (MQW) structure.
- the light absorption layer 62 of the monitor photodiode 60 is made of the same material as the core layer 42 of the first semiconductor optical amplifier 40 and the core layer 52 of the second semiconductor optical amplifier 50, and has the same layer structure. You may
- the upper clad layer 63 is, for example, a p-type InP layer.
- the monitor photodiode 60 has, for example, a high mesa structure.
- the contact layers 64a and 64b are, for example, n-type InGaAs layers, AuZn layers or AuBe layers.
- the electrodes 66a, 66b are made of metal such as Ti, Au, Pt, Nb or Ni, for example.
- An insulating protective layer 37 is formed on the high mesa structure. Specifically, the insulating protective layer 37 is formed on the contact layers 64 a and 64 b, the side surfaces of the upper clad layer 63 and the lower clad layer 61 .
- monitor photodiode 70 has the same configuration as monitor photodiode 60 .
- the monitor photodiodes 70 each include a lower clad layer 71, a light absorption layer 72, an upper clad layer 73, contact layers 74a and 74b, and electrodes 76a and 76b.
- the monitor photodiode 70 may further include an insulating protective layer 37 .
- the light absorption layer 72 of the monitor photodiode 70 is made of the same material and has the same layer structure as the light absorption layer 62 of the monitor photodiode 60 .
- the light absorption layer 72 of the monitor photodiode 70 is made of the same material as the core layer 42 of the first semiconductor optical amplifier 40 and the core layer 52 of the second semiconductor optical amplifier 50, and has the same layer structure. You may
- an optical phase modulating device 2 of the present embodiment is similar to the optical phase modulating device 2 of the first embodiment, but instead of semiconductor optical phase modulator 1, a semiconductor optical phase modulator 1b.
- the controller 7 may receive signals regarding the intensity of the interrogation light from the monitoring photodiodes 60,70.
- the method for inspecting semiconductor optical phase modulator 1b of the present embodiment includes the same steps as the method for inspecting semiconductor optical phase modulator 1 of Embodiment 1, but differs mainly in the following points.
- the method for inspecting semiconductor optical phase modulator 1b of the present embodiment further comprises applying a reverse bias voltage to monitor photodiodes 60 and 70 (S12).
- S4 the voltages applied to the parent phase adjusters 17 and 18
- S4 the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50
- a reverse bias voltage is applied (S2) to the other of the .
- step S1 of the present embodiment is the same as step S1 of the embodiment.
- One of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 functions as a light source for inspection light.
- step S12 a reverse bias voltage is applied to the photodiodes 60 and 70 for monitoring.
- the monitoring photodiodes 60 and 70 can detect inspection light emitted from one of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 .
- step S3 the voltage applied to the child phase adjusters 27 and 28 is adjusted.
- the controller 7 adjusts the voltage applied to the child phase adjusters 27 and 28 so that the intensity of the inspection light detected by the monitor photodiode 70 is maximized.
- step S4 the voltage applied to the parent phase adjusters 17 and 18 is adjusted.
- the controller 7 adjusts the voltage applied to the parent phase adjusters 17 and 18 so that the intensity of the inspection light detected by the monitor photodiode 60 is maximized.
- Step S2 is performed after step S4.
- step S2 a reverse bias voltage is applied to the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50.
- FIG. Therefore, the other of the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 functions as a photodiode that detects inspection light.
- Step S5 is performed following step S2.
- Step S5 of this embodiment is the same as step S5 of the embodiment.
- the semiconductor optical phase modulator 1b of this embodiment further includes a first monitor photodiode (monitor photodiode 60) and a second monitor photodiode (monitor photodiode 70).
- Parent Mach-Zehnder interferometer 10 includes a first 2 ⁇ 2 optical coupler (optical coupler 14) that includes a first optical output port and a second optical output port. The first optical output port is optically coupled to a second semiconductor optical amplifier 50 . The second optical output port is optically coupled to the first monitoring photodiode.
- Two child Mach-Zehnder interferometers 20 each include a second 2 ⁇ 2 optical coupler (optical coupler 24) including a third optical output port and a fourth optical output port.
- a third optical output port is connected to one of the two first arm waveguides 11 , 12 of the parent Mach-Zehnder interferometer 10 .
- the fourth optical output port is optically coupled to the second monitor photodiode.
- the parent phase adjusters 17 and 18 can be adjusted based on the intensity of the detected light detected by the first monitor photodiode (monitor photodiode 60).
- the child phase adjusters 27 and 28 can be adjusted based on the intensity of the detected light detected by the second monitor photodiode (monitor photodiode 70).
- the parent phase adjusters 17, 18 and the child phase adjusters 27, 28 can be adjusted independently of each other.
- the parent phase adjustment units 17 and 18 can more accurately adjust the optical path lengths of the two first arm waveguides 11 and 12, and the child phase adjustment units 27 and 28 can adjust the optical path lengths of the two second arm waveguides 21 and 21. , 22 can be adjusted more accurately.
- the semiconductor optical phase modulator 1b can output phase-modulated signal light of higher quality.
- the first monitor photodiode (monitoring photodiode 60) includes a first light absorption layer (light absorption layer 62) having a fourth multiple quantum well structure.
- the second monitor photodiode (monitor photodiode 70) includes a second light absorption layer (light absorption layer 72) having a fifth multiple quantum well structure.
- the first core layer (core layer 42), the third core layer (core layer 52), the first light absorption layer, and the second light absorption layer are made of the same material and have the same layer structure. have. Therefore, the types of core layers and light absorption layers of the semiconductor optical phase modulator 1b are reduced. The cost of the semiconductor optical phase modulator 1b can be reduced.
- Embodiment 3 The semiconductor optical phase modulator 1c of Embodiment 3 will be described with reference to FIGS. 13 and 14.
- FIG. The semiconductor optical phase modulator 1c of the present embodiment has the same configuration as the semiconductor optical phase modulator 1 of the first embodiment, but differs mainly in the following points.
- the semiconductor optical phase modulator 1 c further includes a third semiconductor optical amplifier 80 .
- the other of the two input ports of optical splitter 23 is optically coupled to third semiconductor optical amplifier 80 .
- the third semiconductor optical amplifier 80 is configured similarly to the first semiconductor optical amplifier 40 and the second semiconductor optical amplifier 50 .
- the third semiconductor optical amplifier 80 includes a lower clad layer 81, a core layer 82, an upper clad layer 83, a current blocking layer 85, and contact layers 84a and 84b. , electrodes 86a and 86b.
- the current blocking layer 85 includes, for example, a p-type semiconductor layer 85a such as p-type InP and an n-type semiconductor layer 85b such as n-type InP.
- the current blocking layer 85 may be a semi-insulating layer such as an Fe-doped InP layer.
- the third semiconductor optical amplifier 80 may further include an insulating protective layer 37 .
- the core layer 82 of the third semiconductor optical amplifier 80 is made of the same material as the core layer 42 of the first semiconductor optical amplifier 40 and the core layer 52 of the second semiconductor optical amplifier 50, and has the same layer structure. You may
- a method for inspecting the semiconductor optical phase modulator 1c of the third embodiment will be described with reference to FIG.
- the method for inspecting the semiconductor optical phase modulator 1c of the present embodiment includes the same steps as the method for inspecting the semiconductor optical phase modulator 1 of the first embodiment, but differs mainly in the following points.
- an optical phase modulating device 2 of the present embodiment is similar to the optical phase modulating device 2 of the first embodiment, but instead of semiconductor optical phase modulator 1, a semiconductor optical phase modulator 1c.
- the controller 7 can also control the current injected into the third semiconductor optical amplifier 80 .
- the method for inspecting the semiconductor optical phase modulator 1c of the present embodiment comprises emitting first inspection light from the first semiconductor optical amplifier 40 and emitting second inspection light from the third semiconductor optical amplifier 80 (S21). , applying a reverse bias voltage to the second semiconductor optical amplifier 50 (S22), and comparing the intensity of the inspection light detected by the second semiconductor optical amplifier 50 with the reference light intensity (S25). Prepare.
- the intensity of the inspection light is the sum of the first intensity of the first inspection light and the second intensity of the second inspection light.
- the inspection method of the semiconductor optical phase modulator 1c according to the present embodiment includes the child phase adjusters. It further comprises adjusting the voltage applied to the units 27 and 28 (S3) and adjusting the voltage applied to the parent phase adjustment units 17 and 18 (S4).
- a forward bias voltage is applied to the first semiconductor optical amplifier 40 and the third semiconductor optical amplifier 80.
- the first semiconductor optical amplifier 40 and the third semiconductor optical amplifier 80 output ASE light.
- ASE light emitted from the first semiconductor optical amplifier 40 is used as first inspection light, and the first semiconductor optical amplifier 40 functions as a first light source for the first inspection light.
- ASE light emitted from the third semiconductor optical amplifier 80 is used as second inspection light, and the third semiconductor optical amplifier 80 functions as a second light source for the second inspection light.
- a reverse bias voltage is applied to the second semiconductor optical amplifier 50.
- the second semiconductor optical amplifier 50 functions as a photodiode that detects the intensity of inspection light.
- the intensity of the inspection light is the sum of the first intensity of the first inspection light and the second intensity of the second inspection light.
- step S3 the voltage applied to the child phase adjusters 27 and 28 is adjusted. Specifically, the controller 7 adjusts the voltage applied to the child phase adjusters 27 and 28 so that the intensity of the inspection light detected by the second semiconductor optical amplifier 50 is maximized.
- step S4 the voltage applied to the parent phase adjusters 17 and 18 is adjusted. Specifically, the controller 7 adjusts the voltage applied to the parent phase adjusters 17 and 18 so that the intensity of the inspection light detected by the second semiconductor optical amplifier 50 is maximized. Steps S3 and S4 may be performed repeatedly.
- the controller 7 compares the intensity of the inspection light detected by the second semiconductor optical amplifier 50 with the reference light intensity. For example, when the intensity of the inspection light is greater than or equal to the reference light intensity, the controller 7 determines that the semiconductor optical phase modulator 1c is non-defective. On the other hand, when the intensity of the inspection light is less than the reference light intensity, the controller 7 determines that the semiconductor optical phase modulator 1c is defective.
- the semiconductor optical phase modulator 1c of this embodiment further includes a third semiconductor optical amplifier 80.
- FIG. Two child Mach-Zehnder interferometers 20 each include a second 2 ⁇ 2 optical splitter (optical splitter 23) including a third optical input port and a fourth optical input port.
- a third optical input port is connected to one of the two first arm waveguides 11 , 12 of the parent Mach-Zehnder interferometer 10 .
- a fourth optical input port is optically coupled to a third semiconductor optical amplifier 80 .
- the inspection light is supplied not only from the first semiconductor optical amplifier 40 but also from the third semiconductor optical amplifier 80.
- the light intensity of the inspection light detected at the second semiconductor optical amplifier 50, which can function as a photodiode, is increased.
- the semiconductor optical phase modulator 1c can be inspected with higher accuracy.
- a forward bias voltage is applied to the first semiconductor optical amplifier 40 and the third semiconductor optical amplifier 80, and the first inspection light is emitted from the first semiconductor optical amplifier 40.
- emitting second inspection light from the third semiconductor optical amplifier 80 (S21); applying a reverse bias voltage to the second semiconductor optical amplifier 50 (S22); Comparing (S25) the intensity of the detected inspection light and a reference light intensity.
- the intensity of the inspection light is the sum of the first intensity of the first inspection light and the second intensity of the second inspection light.
- the inspection light is supplied not only from the first semiconductor optical amplifier 40 but also from the third semiconductor optical amplifier 80.
- the light intensity of the inspection light detected at the second semiconductor optical amplifier 50, which can function as a photodiode, is increased.
- the semiconductor optical phase modulator 1c can be inspected with higher accuracy.
- Embodiments 1 to 3 disclosed this time are examples in all respects and are not restrictive. As long as there is no contradiction, at least two of Embodiments 1 to 3 disclosed this time may be combined.
- the scope of the present disclosure is indicated by the scope of claims rather than the above description, and is intended to include all changes within the meaning and scope of equivalence to the scope of claims.
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Abstract
Description
図1から図6を参照して、実施の形態1の半導体光位相変調器1を説明する。半導体光位相変調器1は、光位相変調素子3と、第一半導体光増幅器40と、第二半導体光増幅器50と、基板9とを主に備える。
第一半導体光増幅器40は、半導体光位相変調器1に入力される光を増幅する。位相変調部25,26に高周波電気信号を印加して、位相変調部25,26のコア層32の屈折率を変化させる。第一アーム導波路11に接続されている子マッハツェンダ干渉計20は、Iチャネル光信号を出力する。第一アーム導波路12に接続されている子マッハツェンダ干渉計20は、Qチャネル光信号を出力する。光カプラ14は、Iチャネル光信号とQチャネル光信号とを合波する。光位相変調素子3は、変調信号光を第二半導体光増幅器50に向けて出力する。第二半導体光増幅器50は、変調信号光を増幅する。こうして、半導体光位相変調器1は、変調信号光を出力する。
本実施の形態の半導体光位相変調器1の検査方法は、第一半導体光増幅器40及び第二半導体光増幅器50の一方から検査光を放射させること(S1)と、第一半導体光増幅器40及び第二半導体光増幅器50の他方に逆バイアス電圧を印加すること(S2)と、第一半導体光増幅器40及び第二半導体光増幅器50の他方において検出される検査光の強度と、基準光強度とを比較することと(S5)を備える。半導体光位相変調器1が親位相調整部17,18と子位相調整部27,28とを備えている場合には、本実施の形態の半導体光位相変調器1の検査方法は、子位相調整部27,28に印加する電圧を調整すること(S3)と、親位相調整部17,18に印加する電圧を調整すること(S4)とをさらに備える。
本実施の形態の半導体光位相変調器1は、光位相変調素子3と、光位相変調素子3に入力される光を増幅する第一半導体光増幅器40と、光位相変調素子3から出力される変調信号光を増幅する第二半導体光増幅器50とを備える。第一半導体光増幅器40は、第一多重量子井戸構造を有する第一コア層(コア層42)を含む。光位相変調素子3は、第二多重量子井戸構造を有する第二コア層(コア層32)を含む。第二半導体光増幅器50は、第三多重量子井戸構造を有する第三コア層(コア層52)を含む。第一コア層の第一厚さは、第二コア層の第二厚さより小さい。第一多重量子井戸構造の第一の井戸層数は、第二多重量子井戸構造の第二の井戸層数より少ない。第三コア層の第三厚さは、第二コア層の第二厚さより小さい。第三多重量子井戸構造の第三の井戸層数は、第二多重量子井戸構造の第二の井戸層数より少ない。半導体光位相変調器1の光入力端は、第一半導体光増幅器40の光入力端面40aである。半導体光位相変調器1の光出力端は、第二半導体光増幅器50の光出力端面50aである。
図9から図12を参照して、実施の形態2の半導体光位相変調器1bを説明する。本実施の形態の半導体光位相変調器1bは、実施の形態1の半導体光位相変調器1と同様の構成を備えるが、主に、以下の点で異なる。
本実施の形態の半導体光位相変調器1bは、第一のモニタ用フォトダイオード(モニタ用フォトダイオード60)と、第二のモニタ用フォトダイオード(モニタ用フォトダイオード70)とをさらに備える。親マッハツェンダ干渉計10は、第一光出力ポートと第二光出力ポートとを含む第一の2×2光カプラ(光カプラ14)を含む。第一光出力ポートは、第二半導体光増幅器50に光学的に結合されている。第二光出力ポートは、第一のモニタ用フォトダイオードに光学的に結合されている。二つの子マッハツェンダ干渉計20は、各々、第三光出力ポートと第四光出力ポートとを含む第二の2×2光カプラ(光カプラ24)を含む。第三光出力ポートは、親マッハツェンダ干渉計10の二本の第一アーム導波路11,12のうちの一つに接続されている。第四光出力ポートは、第二のモニタ用フォトダイオードに光学的に結合されている。
図13及び図14を参照して、実施の形態3の半導体光位相変調器1cを説明する。本実施の形態の半導体光位相変調器1cは、実施の形態1の半導体光位相変調器1と同様の構成を備えるが、主に、以下の点で異なる。
本実施の形態の半導体光位相変調器1cは、第三半導体光増幅器80をさらに備える。二つの子マッハツェンダ干渉計20は、各々、第三光入力ポートと第四光入力ポートとを含む第二の2×2光スプリッタ(光スプリッタ23)を含む。第三光入力ポートは、親マッハツェンダ干渉計10の二本の第一アーム導波路11,12のうちの一つに接続されている。第四光入力ポートは、第三半導体光増幅器80に光学的に結合されている。
32,42,52,82 コア層、33,33b,43,53,63,73,83 上部クラッド層、34,44a,44b,54a,54b,64a,64b,74a,74b,84a,84b コンタクト層、36,46a,46b,56a,56b,66a,66b,76a,76b,86a,86b 電極、37 絶縁保護層、39,49 光導波路、40 第一半導体光増幅器、40a 光入力端面、45,55,65,75,85 電流ブロック層、45a,55a,85a p型半導体層、45b,55b,85b n型半導体層、50 第二半導体光増幅器、50a 光出力端面、60,70 モニタ用フォトダイオード、62,72 光吸収層、80 第三半導体光増幅器。
Claims (11)
- 光位相変調素子と、
前記光位相変調素子に入力される光を増幅する第一半導体光増幅器と、
前記光位相変調素子から出力される変調信号光を増幅する第二半導体光増幅器とを備える半導体光位相変調器において、
前記第一半導体光増幅器は、第一多重量子井戸構造を有する第一コア層を含み、
前記光位相変調素子は、第二多重量子井戸構造を有する第二コア層を含み、
前記第二半導体光増幅器は、第三多重量子井戸構造を有する第三コア層を含み、
前記第一コア層の第一厚さは、前記第二コア層の第二厚さより小さく、
前記第一多重量子井戸構造の第一の井戸層数は、前記第二多重量子井戸構造の第二の井戸層数より少なく、
前記第三コア層の第三厚さは、前記第二コア層の前記第二厚さより小さく、
前記第三多重量子井戸構造の第三の井戸層数は、前記第二多重量子井戸構造の前記第二の井戸層数より少なく、
前記半導体光位相変調器の光入力端は、前記第一半導体光増幅器の光入力端面であり、
前記半導体光位相変調器の光出力端は、前記第二半導体光増幅器の光出力端面である、半導体光位相変調器。 - 前記光位相変調素子と前記第一半導体光増幅器と前記第二半導体光増幅器とが搭載されている基板をさらに備え、
前記第一半導体光増幅器の前記光入力端面は、前記基板の第一端面に面一であり、
前記第二半導体光増幅器の前記光出力端面は、前記第一端面とは異なる前記基板の第二端面に面一である、請求項1に記載の半導体光位相変調器。 - 前記第二半導体光増幅器の長さは、前記第一半導体光増幅器の長さより短い、請求項1または請求項2に記載の半導体光位相変調器。
- 前記第一コア層及び前記第三コア層は、互いに同じ材料で形成されており、かつ、互いに同じ層構造を有している、請求項1から請求項3のいずれか一項に記載の半導体光位相変調器。
- 前記光位相変調素子は、親マッハツェンダ干渉計と、二つの子マッハツェンダ干渉計と、位相変調部とを含み、
前記親マッハツェンダ干渉計は、二本の第一アーム導波路を含み、
前記二つの子マッハツェンダ干渉計は、それぞれ、前記二本の第一アーム導波路に接続されており、かつ、前記二つの子マッハツェンダ干渉計は、各々、二本の第二アーム導波路を含み、
前記位相変調部は、前記二本の第二アーム導波路に設けられている、請求項1から請求項4のいずれか一項に記載の半導体光位相変調器。 - 前記光位相変調素子は、親位相調整部と、子位相調整部とをさらに含み、
前記親位相調整部は、前記二本の第一アーム導波路に設けられており、
前記子位相調整部は、前記二本の第二アーム導波路に設けられている、請求項5に記載の半導体光位相変調器。 - 第一のモニタ用フォトダイオードと、
第二のモニタ用フォトダイオードとをさらに備え、
前記親マッハツェンダ干渉計は、第一光出力ポートと第二光出力ポートとを含む第一の2×2光カプラを含み、
前記第一光出力ポートは、前記第二半導体光増幅器に光学的に結合されており、
前記第二光出力ポートは、前記第一のモニタ用フォトダイオードに光学的に結合されており、
前記二つの子マッハツェンダ干渉計は、各々、第三光出力ポートと第四光出力ポートとを含む第二の2×2光カプラを含み、
前記第三光出力ポートは、前記親マッハツェンダ干渉計の前記二本の第一アーム導波路のうちの一つに接続されており、
前記第四光出力ポートは、前記第二のモニタ用フォトダイオードに光学的に結合されている、請求項6に記載の半導体光位相変調器。 - 前記第一のモニタ用フォトダイオードは、第四多重量子井戸構造を有する第一光吸収層を含み、
前記第二のモニタ用フォトダイオードは、第五多重量子井戸構造を有する第二光吸収層を含み、
前記第一コア層、前記第三コア層、前記第一光吸収層及び前記第二光吸収層は、互いに、同じ材料で形成されており、かつ、互いに同じ層構造を有している、請求項7に記載の半導体光位相変調器。 - 第三半導体光増幅器をさらに備え、
前記二つの子マッハツェンダ干渉計は、各々、第三光入力ポートと第四光入力ポートとを含む第二の2×2光スプリッタを含み、
前記第三光入力ポートは、前記親マッハツェンダ干渉計の前記二本の第一アーム導波路のうちの一つに光学的に結合されており、
前記第四光入力ポートは、前記第三半導体光増幅器に光学的に結合されている、請求項5から請求項8のいずれか一項に記載の半導体光位相変調器。 - 前記第一半導体光増幅器及び前記第二半導体光増幅器の一方に順バイアス電圧を印加して、前記第一半導体光増幅器及び前記第二半導体光増幅器の前記一方から検査光を放射させることと、
前記第一半導体光増幅器及び前記第二半導体光増幅器の他方に逆バイアス電圧を印加することと、
前記第一半導体光増幅器及び前記第二半導体光増幅器の前記他方において検出される前記検査光の強度と、基準光強度とを比較することとを備える、請求項1から請求項9のいずれか一項に記載の半導体光位相変調器の検査方法。 - 前記第一半導体光増幅器及び前記第三半導体光増幅器に順バイアス電圧を印加して、前記第一半導体光増幅器から第一検査光を放射させるとともに、前記第三半導体光増幅器から第二検査光を放射させることと、
前記第二半導体光増幅器に逆バイアス電圧を印加することと、
前記第二半導体光増幅器において検出される検査光の強度と、基準光強度とを比較することとを備え、前記検査光の前記強度は、前記第一検査光の第一強度と前記第二検査光の第二強度との和である、請求項9に記載の半導体光位相変調器の検査方法。
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JPH10319454A (ja) * | 1997-04-10 | 1998-12-04 | Alcatel Alsthom Co General Electricite | 二進光信号の波長変換器 |
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