WO2010137458A1 - 半導体光変調器および半導体マッハツェンダー型光変調器 - Google Patents
半導体光変調器および半導体マッハツェンダー型光変調器 Download PDFInfo
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- 230000003287 optical effect Effects 0.000 title claims abstract description 227
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Images
Classifications
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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
- G02F1/015—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
- G02F1/225—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
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/06—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 integrated waveguide
- G02F2201/063—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 integrated waveguide ridge; rib; strip loaded
-
- 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
- G02F2202/00—Materials and properties
- G02F2202/06—Materials and properties dopant
Definitions
- the present invention relates to a semiconductor optical modulator and a semiconductor Mach-Zehnder optical modulator.
- a method for increasing the capacity of communication traffic for example, a method of multiplexing the wavelength of signal light and simultaneously increasing the number of channels for transmitting optical fibers (Wavelength Division Multiplexing (WDM)), and for each channel And a method for improving the transmission amount (transmission speed) per unit time.
- WDM Wavelength Division Multiplexing
- a method for improving the transmission amount (transmission speed) per unit time for example, a method of modulating signal light at high speed can be mentioned.
- Examples of a method for modulating the signal light at high speed include a method for directly modulating signal light from a semiconductor laser used as a light source and a method for indirectly (externally) modulating signal light from the semiconductor laser. .
- output light (signal light) of the semiconductor laser is directly modulated by modulating a drive current to the semiconductor laser.
- the direct modulation method is widely used because the device configuration can be simplified.
- the modulation speed of the signal light by the direct modulation method is limited by the response speed of the semiconductor laser. Therefore, the direct modulation method is not suitable for modulating signal light at a higher speed.
- the semiconductor laser is operated with a direct current, and the signal light is modulated by an external modulator which is another optical element in a state where the intensity of the signal light is kept constant.
- the external modulator include a Mach-Zehnder optical modulator (LN modulator) using a LiNbO 3 crystal as a material.
- LN modulator Mach-Zehnder optical modulator
- the LN modulator is suitable for a WDM system because it has a wavelength-independent modulation characteristic.
- the LN modulator has a problem that the drive voltage is high (for example, 5 V or more) and the device size is large (for example, 10 cm or more). Therefore, a semiconductor optical modulator capable of lowering the voltage and reducing the size has been developed.
- a semiconductor optical modulator for example, a multiple quantum well is used as a core layer, and a change in refractive index due to voltage application is utilized by a quantum confined Stark effect (QCSE).
- QCSE quantum confined Stark effect
- a material based on, for example, indium phosphide (InP) or gallium arsenide (GaAs) is used as a semiconductor material.
- a Mach-Zehnder type optical modulator (semiconductor MZM) using this semiconductor optical modulator has been put into practical use in recent years because it has a low driving voltage (for example, 2 V) and a small device size (for example, about 2 mm). Yes.
- the semiconductor optical modulator can be integrated with, for example, another optical element such as a semiconductor laser or an optical amplifier, an electronic circuit, or the like.
- a semiconductor optical modulator having a pin type layer structure shown in FIG. 12 is generally used (see, for example, Patent Document 1).
- the semiconductor optical modulator 120 a high mesa waveguide structure in which an n-type semiconductor layer 122, an optical modulation layer 123, and a p-type semiconductor layer 124 are stacked in the above order is formed on a substrate 121.
- An insulating protective film 129 is provided on the side surface of the high mesa waveguide structure.
- An arrow B indicates a boundary between the high mesa waveguide structure and the insulating protective film 129.
- FIG. 14A shows an example of a band diagram of the semiconductor optical modulator 120.
- band diagrams 124a, 123a and 122a respectively correspond to the p-type semiconductor layer 124, the light modulation layer 123 and the n-type semiconductor layer 122 of the semiconductor optical modulator 120 shown in FIG. It is a diagram.
- the optical modulation layer 123 is sandwiched between the n-type semiconductor layer 122 and the p-type semiconductor layer 124.
- Signal light is guided to the light modulation layer 123, and the guided signal light is subjected to refractive index modulation by a voltage applied to the light modulation layer 123.
- the light modulation layer 123 has a multiple quantum well as a core layer, and is usually an undoped layer (i layer).
- the impurity concentration of the n-type semiconductor layer 122 or the p-type semiconductor layer 124 is 10 17 cm ⁇ 3 or more, and the impurity concentration of the undoped layer (i layer) is 10 16 cm ⁇ 3 or less.
- the semiconductor MZM using the semiconductor optical modulator having the pin type layer structure has a problem that the optical propagation loss in the p-type semiconductor layer is larger than that of the LN modulator.
- a semiconductor MZM having a length on the order of millimeters may be used in the traveling direction of the signal light. Therefore, this light propagation loss is a problem that cannot be ignored.
- a semiconductor optical modulator having an nn type layer structure not including a p type semiconductor layer, or a semiconductor optical modulator having an n-SI-in type layer structure has been proposed (for example, a patent).
- Reference 2 The “SI layer” means a semi-insulated semiconductor layer, and the impurity concentration of the SI layer is negligibly small. With these structures, light propagation loss can be reduced. However, in these semiconductor optical modulators, the electric field applied to the undoped layer (i layer) is smaller than that of the semiconductor optical modulator having the above-described pin type layer structure.
- FIG. 13A is a perspective view of the semiconductor optical modulator
- FIG. 13B is a cross-sectional view of FIG. 13A viewed in the II direction.
- the same parts are denoted by the same reference numerals.
- a first n-InP cladding layer 132, an optical modulation layer (i layer) 133, an SI cladding layer 137, and a second n-InP are formed on a substrate 131.
- a high mesa waveguide structure in which the clad layer 135 is laminated in the above-described order is formed.
- a part of the second n-InP cladding layer 135 in a section having a certain length in the traveling direction of the signal light is a p-type semiconductor region 138.
- An insulating protective film 139 is provided on the side surface of the high mesa waveguide structure.
- An arrow C indicates a boundary between the high mesa waveguide structure and the insulating protective film 139. In FIG. 13A, illustration of the insulating protective film 139 is omitted.
- FIG. 14B shows an example of a band diagram of the semiconductor optical modulator 130.
- the band diagrams 135a, 138a, 137a, 133a, and 132a are respectively the second n-InP cladding layer 135, the p-type semiconductor region 138, and the like of the semiconductor optical modulator 130 shown in FIG. 4 is a band diagram corresponding to an SI clad layer 137, the light modulation layer (i layer) 133, and the first n-InP clad layer 132.
- the optical propagation loss can be reduced by appropriately setting the thickness of the p-type semiconductor region 138 and a sufficient electric field can be applied to the optical modulation layer (i layer) 133. It is said that.
- FIG. 14C is a diagram comparing the band diagram 120a of the semiconductor optical modulator 120 and the band diagram 130a of the semiconductor optical modulator 130 described above.
- the same parts as those in FIGS. 14A and 14B are denoted by the same reference numerals.
- the band diagram 120a is indicated by a broken line
- the band diagram 130a is indicated by a solid line.
- the position of the band diagram 122a is matched with the position of the band diagram 132a
- the position of the band diagram 123a is matched with the position of the band diagram 133a
- the position of the band diagram 124a is changed to the band diagram 135a. 138a and 137a.
- the p-type semiconductor region 138 is set relatively thin (for example, 0.05 to 0.2 ⁇ m) for the purpose of reducing the optical propagation loss. Therefore, for example, even if the impurity concentration of the p-type semiconductor region 138 is set high (for example, 1 ⁇ 10 17 to 1 ⁇ 10 18 cm ⁇ 3 ), as compared with the p-type semiconductor layer 124 as shown in the figure. Thus, the amount of potential lift by the p-type semiconductor region 138 and the SI cladding layer 137 is reduced. As a result, the electric field applied to the light modulation layer (i layer) 133 is relatively lowered. For this reason, in the semiconductor optical modulator 130, it is necessary to increase the voltage required for modulation.
- FIG. 15 shows the electric field strength obtained by differentiating the potential in the band diagrams 120a and 130a.
- a layer direction coordinate X1 indicates a layer direction coordinate of the semiconductor optical modulator 120
- a layer direction coordinate X2 indicates a layer direction coordinate of the semiconductor optical modulator 130.
- a graph indicating the electric field of the semiconductor optical modulator 120 is indicated by a broken line
- a graph indicating the electric field of the semiconductor optical modulator 130 is indicated by a solid line.
- the same parts as those in FIGS. 12 and 13 are denoted by the same reference numerals.
- the graph indicated by reference numeral 151a is a graph showing the electric field when the impurity concentration of the p-type semiconductor region 138 of the semiconductor optical modulator 130 is 1 ⁇ 10 18 cm ⁇ 3, and the graph indicated by reference numeral 151b These are graphs showing the electric field when the impurity concentration of the p-type semiconductor region 138 of the semiconductor optical modulator 130 is set to 1 ⁇ 10 17 cm ⁇ 3 .
- the electric field 152 a applied to the light modulation layer (i layer) 133 of the semiconductor light modulator 130 is the light modulation layer (undoped layer (i layer)) 123 of the semiconductor light modulator 120. Is smaller than the electric field 152b applied to.
- the peak electric field 153a or 153b is applied to the junction between the second n-InP cladding layer 135 and the p-type semiconductor region 138 due to the steep potential. Is done.
- a particularly high electric field is applied from the central portion of the semiconductor layer, for example, the p-type
- the peak electric field reaches 200 to 400 kV / cm, for example, as shown in FIG.
- the dielectric breakdown may occur at, for example, 500 to 600 kV / cm. In this state, further application of the electric field may cause the electric field to ooze out and cause dielectric breakdown in the insulating protective film. There is sex. The possibility of such a dielectric breakdown, for example, significantly reduces the reliability of the device.
- An object of the present invention is to provide a semiconductor optical modulator and a semiconductor Mach-Zehnder optical modulator that are highly efficient and highly reliable.
- a semiconductor optical modulator of the present invention includes: A waveguide structure is formed by laminating the first n-type cladding layer, the semiconductor light modulation layer, the p-type cladding layer, and the second n-type cladding layer in the above order on the substrate.
- the insulating protective film is disposed on a side surface of the waveguide structure,
- the p-type cladding layer and the second n-type cladding layer are laminated via the electric field relaxation layer,
- the impurity concentration of the electric field relaxation layer is lower than the impurity concentration of the p-type cladding layer and the impurity concentration of the second n-type cladding layer.
- the semiconductor Mach-Zehnder optical modulator of the present invention is Optical demultiplexing means for demultiplexing input light, a first semiconductor optical modulator and a second semiconductor optical modulator for modulating the demultiplexed light, and the first semiconductor optical modulator on a substrate And a multiplexing means for multiplexing the light modulated by the second semiconductor optical modulator, At least one of the first semiconductor optical modulator and the second semiconductor optical modulator is the semiconductor optical modulator of the present invention.
- the semiconductor optical modulator of the present invention and the semiconductor Mach-Zehnder optical modulator of the present invention are highly efficient and highly reliable.
- FIG. 1 It is sectional drawing which shows the structure of an example in Embodiment 1 of the semiconductor optical modulator of this invention. It is a figure which shows an example band diagram in Embodiment 1 of the semiconductor optical modulator of this invention. It is a graph which shows the relationship between the layer direction coordinate of an example in Embodiment 1 of the semiconductor optical modulator of this invention, and an electric field. It is sectional drawing which shows the structure of the other example in Embodiment 1 of the semiconductor optical modulator of this invention. (A) is sectional drawing which shows the structure of an example in Embodiment 2 of the semiconductor optical modulator of this invention, (b) is a figure which shows the band diagram of an example in Embodiment 2. FIG.
- (A) is sectional drawing which shows the other structure in Embodiment 2 of the semiconductor optical modulator of this invention
- (b) is a figure which shows the band diagram of the other example in Embodiment 2.
- FIG. It is sectional drawing which shows the further another structure in Embodiment 2 of the semiconductor optical modulator of this invention.
- (A) is sectional drawing which shows the structure of an example in Embodiment 3 of the semiconductor optical modulator of this invention
- (b) is a figure which shows the relationship between the layer direction coordinate of an example in Embodiment 3, and impurity concentration. is there.
- FIG. (A) is sectional drawing which shows the structure of the other example in Embodiment 3 of the semiconductor optical modulator of this invention
- (b) is the relationship between the layer direction coordinate of other examples in Embodiment 3, and impurity concentration.
- FIG. (A) is sectional drawing which shows the structure of the further another example in Embodiment 3 of the semiconductor optical modulator of this invention
- (b) is a layer direction coordinate and impurity concentration of the other example in Embodiment 3.
- (A) is a perspective view showing a configuration of another example of a conventional semiconductor optical modulator
- (b) is a cross-sectional view of the semiconductor optical modulator shown in (a) as viewed in the II direction.
- It is a figure which shows the band diagram of the conventional semiconductor optical modulator.
- It is a graph which shows the relationship between the layer direction coordinate of the conventional semiconductor optical modulator, and an electric field.
- FIG. 1 shows a configuration of an example of a semiconductor optical modulator according to the present embodiment.
- a first n-InP clad layer 12 an undoped layer (i layer) 13 having a multiple quantum well structure, and a p-InP clad layer 14 are formed on an InP substrate 11.
- the second n-InP clad layer 15 are laminated in the above-described order to form a high mesa waveguide structure.
- the p-InP cladding layer 14 and the second n-InP cladding layer 15 are laminated via an electric field relaxation layer 16.
- the impurity concentration of the electric field relaxation layer 16 is set lower than the impurity concentration of the p-InP cladding layer 14 and the impurity concentration of the second n-InP cladding layer 15.
- An insulating protective film 19 is provided on the surface of the waveguide structure (left and right side surfaces in the figure).
- An arrow A indicates a boundary between the high mesa waveguide structure and the insulating protective film 19.
- the waveguide structure is a high mesa waveguide structure, and the substrate, the first n-type cladding layer, the p-type cladding layer, and the second n-type cladding layer are formed.
- the material is InP, and the semiconductor light modulation layer is an undoped layer (i layer) having a multiple quantum well structure.
- i layer an undoped layer having a multiple quantum well structure.
- an n-type InGaAs contact layer is provided on the second n-InP cladding layer 15 in order to reduce the electrical resistance at the junction with the electrode. It is omitted in the modulator 10.
- the impurity concentration of the p-InP cladding layer 14 is about 2 ⁇ 10 17 cm ⁇ 3, and the impurity concentration of the second n-InP cladding layer 15 is about 5 ⁇ 10 17 cm ⁇ 3.
- An example of the band diagram of the semiconductor optical modulator 10 of the present embodiment when the impurity concentration of the electric field relaxation layer 16 is about 2 ⁇ 10 16 cm ⁇ 3 is shown.
- band diagrams 15a, 16a, 14a, 13a and 12a are respectively the second n-InP clad layer 15, the electric field relaxation layer 16, the p-InP clad layer 14 shown in FIG. 3 is a band diagram corresponding to the undoped layer (i layer) 13 and the first n-InP clad layer 12.
- FIG. 3 shows the electric field strength obtained by differentiating the potential in the band diagram 10a.
- an electric field 32 applied between the p-InP cladding layer 14 and the second n-InP cladding layer 15 (the electrolytic relaxation layer 16) by the electric field relaxation layer 16 is about 100 kV / It is reduced to about cm.
- the electric field applied to the boundary between the high mesa waveguide structure indicated by the arrow A and the insulating protective film 19 in FIG. 1 can be reduced.
- dielectric breakdown of the insulating protective film 19 can be prevented, and the semiconductor optical modulator of this embodiment has high reliability.
- the applied electric field can be reduced, a large voltage can be applied.
- the electric field 31 applied to the undoped layer (i layer) 13 can be improved.
- the amount of light existing in the p-InP cladding layer standardized confinement rate of light
- the semiconductor optical modulator of this embodiment is highly efficient.
- the waveguide structure is a high-mesa waveguide structure, but the present invention is not limited to this.
- the waveguide structure include structures capable of guiding signal light, such as a ridge waveguide structure, a high mesa ridge waveguide structure, and a semiconductor buried waveguide, in addition to the high mesa waveguide structure.
- the impurity concentration of the electric field relaxation layer is lower than the impurity concentration of the p-InP cladding layer and the impurity concentration of the second n-InP cladding layer.
- the impurity concentration of the electric field relaxation layer is preferably as low as possible in view of improving the effect as the electric field relaxation layer.
- the impurity concentration of the electric field relaxation layer is, for example, in the range of about 1 ⁇ 10 15 to about 2 ⁇ 10 17 cm ⁇ 3 , and preferably in the range of about 1 ⁇ 10 15 to about 1 ⁇ 10 17 cm ⁇ 3 . More preferably, it is in the range of about 1 ⁇ 10 15 to about 5 ⁇ 10 16 cm ⁇ 3 .
- the electric field relaxation layer may be n-type or p-type, for example.
- the electric field relaxation layer is a single layer, but the present invention is not limited to this, and the electric field relaxation layer may be a multilayer.
- the impurities conventionally known impurities can be used.
- the first n-InP cladding layer and the second n-InP cladding layer include sulfur, silicon, tin, and the like.
- the p-InP cladding layer Then, zinc, beryllium, cadmium, etc. are mention
- the material of the substrate, the first n-type cladding layer, the p-type cladding layer, and the second n-type cladding layer is InP, but the present invention is not limited to this.
- the material include InP, for example, GaAs, InGaAsP, InAlAs, GaAlAs, and the like.
- the impurity concentration of the p-InP cladding layer only needs to be higher than the impurity of the electric field relaxation layer.
- the impurity concentration of the p-InP cladding layer is, for example, in the range of about 2 ⁇ 10 17 to about 5 ⁇ 10 19 cm ⁇ 3 , and preferably in the range of about 5 ⁇ 10 17 to about 5 ⁇ 10 18 cm ⁇ 3 . And more preferably in the range of about 5 ⁇ 10 17 to about 1 ⁇ 10 18 cm ⁇ 3 .
- the p-type cladding layer is formed of a material other than InP.
- the thickness of the p-InP clad layer is not particularly limited, but it is preferably thin as long as the effects of the present invention are not impaired. By reducing the thickness of the p-InP cladding layer, for example, light propagation loss can be further reduced.
- the thickness of the p-InP cladding layer is, for example, in the range of about 0.1 to about 0.5 ⁇ m, preferably in the range of about 0.15 to about 0.4 ⁇ m, and more preferably about 0.2. The range is about 0.3 ⁇ m. The same applies when the p-type cladding layer is formed of a material other than InP.
- the impurity concentration of the second n-InP cladding layer may be higher than the impurity concentration of the electric field relaxation layer.
- the impurity concentration of the second n-InP cladding layer is, for example, in the range of about 5 ⁇ 10 17 to about 5 ⁇ 10 19 cm ⁇ 3 , and preferably about 1 ⁇ 10 18 to about 2 ⁇ 10 19 cm ⁇ . 3 , more preferably from about 2 ⁇ 10 18 to about 1 ⁇ 10 19 cm ⁇ 3 .
- the thickness of the second n-InP cladding layer is not particularly limited. The same applies to the case where the second n-type cladding layer is formed of a material other than InP.
- the material of the undoped layer (i layer) examples include InGaAsP, InGaAlAs, InAlAs, GaAlAs, GaInNAs, InGaAlAsP, and the like.
- the impurity concentration of the undoped layer (i layer) is, for example, less than about 1 ⁇ 10 17 cm ⁇ 3 .
- the semiconductor optical modulation layer is an undoped layer (i layer) having a multiple quantum well structure, but the present invention is not limited to this.
- the semiconductor optical modulator of the present invention When the semiconductor optical modulator of the present invention is used for a phase modulator of a semiconductor Mach-Zehnder optical modulator, for example, the band gap of the optical modulation layer, the number of quantum well layers, the quantum well width, etc. operate as the phase modulator. What is necessary is just to set so that it becomes possible.
- the active layer (light modulation layer) in the phase modulation region preferably has a band gap that does not cause amplification or light loss at the wavelength of the signal light.
- the material of the insulating protective film for example, various conventionally known materials can be used as long as they have insulating properties.
- the material for the insulating protective film include silicon oxide (SiO 2 ), silicon nitride (SiN), and silicon nitride oxide (SiON).
- the semiconductor optical modulator of the present embodiment can be manufactured, for example, as follows. That is, first, the first n-InP cladding layer is formed on the entire surface of one surface of the InP substrate in order from the bottom by a crystal growth technique such as metal organic vapor phase epitaxy (MOVPE: Metal-Organic Vapor Phase Epitaxy). An undoped layer (i layer) including a multiple quantum well structure, a p-InP cladding layer, an electric field relaxation layer, and a second n-InP cladding layer are formed.
- MOVPE Metal-Organic Vapor Phase Epitaxy
- the electric field relaxation layer is doped with an impurity concentration lower than the impurity concentration of the p-InP cladding layer stacked above and below the impurity concentration of the second n-InP cladding layer.
- the impurity concentration of each layer can be set by a conventionally known method.
- an unnecessary InP layer is removed by a semiconductor etching technique and etched down to the bottom of the undoped layer (i layer). Processed into a high mesa waveguide structure.
- an electrode is formed on the back surface of the InP substrate and a contact layer provided on the second n-InP clad layer.
- an insulating protective film such as SiO 2 or SiN is provided on the entire top.
- a semiconductor optical modulator is formed by opening an upper portion of a region where the semiconductor optical modulator is to be formed and depositing a metal film on the opening. In this way, the semiconductor optical modulator of this embodiment can be manufactured.
- the method for manufacturing the semiconductor optical modulator of the present embodiment is not limited to this example.
- the waveguide structure may be a ridge waveguide structure.
- FIG. 4 shows a configuration of an example of the semiconductor optical modulator of this form. In this figure, the same parts as those in FIG. As shown in the figure, in this semiconductor optical modulator 40, a first n-InP cladding layer 42, an undoped layer (i layer) 43, a p-InP cladding layer 14, and a second n-type layer are formed on an InP substrate 11.
- the InP clad layer 15 is laminated in the above order and has a ridge waveguide structure.
- An insulating protective film 49 is provided on the surface of the waveguide structure (left and right side surfaces in FIG. 4).
- Other configurations are the same as those of the semiconductor optical modulator 10 described above. Even with such a configuration, it is possible to achieve the same effects as the semiconductor optical modulator 10 described above.
- FIG. 5A shows an exemplary configuration of the semiconductor optical modulator according to the present embodiment.
- a first n-InP clad layer 12, an undoped layer (i layer) 13, a p-InP clad layer 14, and a second n-type are formed on an InP substrate 11.
- the InP clad layer 15 is laminated in the above order and has a high mesa waveguide structure.
- the p-InP clad layer 14 and the second n-InP clad layer 15 are laminated via an electric field relaxation layer 56.
- the electric field relaxation layer 56 is an n-InP clad layer (n ⁇ -InP clad layer) having an impurity concentration lower than that of the second n-InP clad layer 15.
- the impurity concentration of the n ⁇ -InP cladding layer 56 is set lower than the impurity concentration of the p-InP cladding layer 14.
- An insulating protective film 59 is provided on the surface of the waveguide structure (left and right side surfaces in FIG. 5A). The rest is the same as the semiconductor optical modulator of the first embodiment.
- the impurity concentration of the p-InP cladding layer 14 is about 1 ⁇ 10 18 cm ⁇ 3
- the impurity concentration of the second n-InP cladding layer 15 is about 5 ⁇ 10 18 cm 3.
- 3 is an example of a band diagram of the semiconductor optical modulator 50 of the present embodiment when the impurity concentration of the n ⁇ -InP cladding layer 56 is about 2 ⁇ 10 17 cm ⁇ 3 .
- the band diagrams 15a, 56a, 14a, 13a and 12a are respectively the second n-InP cladding layer 15, the n ⁇ -InP cladding layer 56 and the p shown in FIG. FIG.
- FIG. 4 is a band diagram corresponding to the InP cladding layer 14, the undoped layer (i layer) 13, and the first n-InP cladding layer 12.
- the semiconductor optical modulator of this embodiment in addition to the effects exhibited by the semiconductor optical modulator of Embodiment 1, it is possible to set the impurity concentration of the second n-InP cladding layer high, The element resistance can be reduced.
- the impurity concentration of the n ⁇ -InP cladding layer is, for example, in the range of about 1 ⁇ 10 17 to about 2 ⁇ 10 17 cm ⁇ 3 .
- the impurity concentration of the second n-InP cladding layer is, for example, in the range of about 5 ⁇ 10 18 to about 5 ⁇ 10 19 cm ⁇ 3 .
- this semiconductor optical modulator is not limited to this example.
- the semiconductor optical modulator of the present embodiment includes, for example, the p-InP cladding layer, the n ⁇ -InP cladding layer, and the second n-InP cladding in the lamination of each layer on the InP substrate by the MOVPE method or the like.
- the layer can be manufactured in the same manner as the semiconductor optical modulator of the first embodiment except that the impurity concentration of the layer is set to the predetermined concentration.
- the electric field relaxation layer may be a p-InP cladding layer having an impurity concentration lower than that of the p-InP cladding layer.
- FIG. 6A shows an example of the configuration of this semiconductor optical modulator. In this figure, the same parts as those in FIG. As shown in the figure, in the semiconductor optical modulator 60, the p-InP cladding layer 14 and the second n-InP cladding layer 15 are laminated via an electric field relaxation layer 66.
- the electric field relaxation layer 66 is a p-InP cladding layer (p ⁇ -InP cladding layer) having an impurity concentration lower than that of the p-InP cladding layer 14.
- the impurity concentration of the p ⁇ —InP cladding layer 66 is set lower than the impurity concentration of the second n-InP cladding layer 15. The rest is the same as the semiconductor optical modulator 50 described above.
- the impurity concentration of the p-InP cladding layer 14 is about 2 ⁇ 10 18 cm ⁇ 3
- the impurity concentration of the second n-InP cladding layer 15 is about 5 ⁇ 10 18 cm 3.
- 3 is an example of a band diagram of the semiconductor optical modulator 60 of the present embodiment when the impurity concentration of the p ⁇ -InP cladding layer 66 is about 2 ⁇ 10 17 cm ⁇ 3 .
- the band diagrams 15a, 66a, 14a, 13a and 12a are respectively the second n-InP cladding layer 15, the p ⁇ -InP cladding layer 66, the p shown in FIG. FIG.
- the impurity concentration of the p-InP cladding layer can be set high in addition to the effects exhibited by the semiconductor optical modulator of the first embodiment.
- the electric field applied to the layer (i layer) can be improved, and as a result, the modulation efficiency can be improved.
- the impurity concentration of the p ⁇ -InP cladding layer is, for example, in the range of about 1 ⁇ 10 17 to about 2 ⁇ 10 17 cm ⁇ 3 .
- the impurity concentration of the p-InP cladding layer is, for example, in the range of about 5 ⁇ 10 18 to about 5 ⁇ 10 19 cm ⁇ 3 .
- this semiconductor optical modulator is not limited to this example.
- the semiconductor optical modulator of the present embodiment for example, the electric field relaxation layer, the n on the second n-InP cladding layer side - comprises -InP cladding layer, wherein on the p-InP cladding layer side p - -An InP cladding layer may be included.
- FIG. 7 shows a configuration of an example of this semiconductor optical modulator. In this figure, the same parts as those in FIG. As shown in the figure, in the semiconductor optical modulator 70, the p-InP cladding layer 14 and the second n-InP cladding layer 15 are laminated via an electric field relaxation layer 76.
- an n ⁇ —InP cladding layer 76 a and a p ⁇ —InP cladding layer 76 b are stacked, and the n ⁇ —InP cladding layer 76 a is disposed on the second n-InP cladding layer 15 side.
- the p ⁇ -InP clad layer 76b is disposed on the p-InP clad layer 14 side.
- the rest is the same as the semiconductor optical modulators 50 and 60 described above. In this semiconductor optical modulator, in addition to the effects achieved by the semiconductor optical modulator of the first embodiment, it is possible to obtain both effects achieved by the above-described semiconductor optical modulators 50 and 60.
- FIG. 8A shows a configuration of an example of the semiconductor optical modulator of the present embodiment.
- the semiconductor optical modulator of the present embodiment has an electric field relaxation region at the interface portion between the p-InP cladding layer and the second n-InP cladding layer instead of the electric field relaxation layer described above.
- a region including the interface portion of the n-InP clad layer 2 is the electric field relaxation region.
- this semiconductor optical modulator 80 a first n-InP clad layer 12, an undoped layer (i layer) 13, a p-InP clad layer 14, and a second n-type are formed on an InP substrate 11.
- the InP clad layer 85 is laminated in the above order and has a high mesa waveguide structure.
- An insulating protective film 89 is provided on the surface of the waveguide structure (left and right side surfaces in FIG. 8A).
- a region including the interface portion of the second n-InP cladding layer 85 is an electric field relaxation region 86.
- the impurity concentration of the electric field relaxation region 86 has a gradient that decreases toward the p-InP cladding layer 14 side. Further, the impurity concentration is lower than the impurity concentration of the p-InP cladding layer 14 near the middle of the electric field relaxation region 86.
- the rest is the same as the semiconductor optical modulator of the first or second embodiment.
- FIG. 8B the same parts as those in FIG. In the semiconductor optical modulator according to the present embodiment, in addition to the effects exhibited by the semiconductor optical modulator according to the first embodiment, it is possible to obtain the same effects as those of the semiconductor optical modulator 50 described above.
- the semiconductor optical modulator of the present embodiment almost the entire region including the interface portion of the second n-InP cladding layer is an electric field relaxation region.
- the region including at least the interface portion of the second n-InP cladding layer may be an electric field relaxation region.
- the impurity concentration of the electric field relaxation region is linearly decreased with respect to the layer direction coordinates, but the present invention is not limited to this.
- the impurity concentration may be decreased stepwise, for example.
- the impurity concentration in the electric field relaxation region is lower than the impurity concentration in the p-InP cladding layer in the vicinity of the middle of the electric field relaxation region.
- the present invention is not limited to this. For example, it is sufficient that the minimum value of the impurity concentration in the electric field relaxation region is lower than the impurity concentration in the p-InP cladding layer.
- the semiconductor optical modulator of the present embodiment for example, in the lamination of each layer on the InP substrate by the MOVPE method or the like, from the p-InP cladding layer side when the second n-InP cladding layer is laminated.
- the semiconductor optical modulator can be manufactured in the same manner as in the first or second embodiment except that the second n-InP cladding layer is formed so that the impurity concentration is increased based on the concentration gradient.
- the region including the interface portion of the p-InP cladding layer may be an electric field relaxation region.
- FIG. 9A shows an example of the configuration of this semiconductor optical modulator. In this figure, the same parts as those in FIG. As shown in the figure, in this semiconductor optical modulator 90, a first n-InP clad layer 12, an undoped layer (i layer) 13, a p-InP clad layer 94, and a second n-type are formed on an InP substrate 11.
- the InP clad layer 15 is laminated in the above order and has a high mesa waveguide structure.
- a region including the interface portion of the p-InP cladding layer 94 is an electric field relaxation region 96.
- the impurity concentration of the electric field relaxation region 96 has a gradient that decreases toward the second n-InP cladding layer 15 side.
- the rest is the same as the semiconductor optical modulator 80 described above.
- the same parts as those in FIG. 9A are denoted by the same reference numerals.
- this semiconductor optical modulator in addition to the effects exhibited by the semiconductor optical modulator of the first embodiment, it is possible to obtain the same effects as those of the semiconductor optical modulator 60 described above.
- the region including the interface portion of the second n-InP cladding layer and the region including the interface portion of the p-InP cladding layer are electric field relaxation regions.
- FIG. 10A shows an example of the configuration of this semiconductor optical modulator. In this figure, the same parts as those in FIG. As shown in the figure, in this semiconductor optical modulator 100, a first n-InP clad layer 12, an undoped layer (i layer) 13, a p-InP clad layer 104, and a second n-type are formed on an InP substrate 11.
- the InP clad layer 105 is laminated in the above order and has a high mesa waveguide structure.
- the region 106 a including the interface portion of the second n-InP cladding layer 105 and the region 106 b including the interface portion of the p-InP cladding layer 104 are electric field relaxation regions 106.
- the impurity concentration of the region 106a has a gradient that decreases toward the p-InP cladding layer 104 side.
- the impurity concentration of the region 106b has a gradient that decreases toward the second n-InP cladding layer 105 side.
- the rest is the same as the semiconductor optical modulator 80 described above. 10B, the same parts as those in FIG. 10A are denoted by the same reference numerals.
- this semiconductor optical modulator in addition to the effects exhibited by the semiconductor optical modulator of the first embodiment, it is possible to obtain the same effects as those of the semiconductor optical modulators 50 and 60 described above.
- FIG. 11 shows a configuration of an example of the semiconductor Mach-Zehnder optical modulator according to this embodiment.
- the semiconductor Mach-Zehnder optical modulator 110 includes a first phase modulation waveguide 112 and a second phase modulation waveguide 113 and optical multiplexers / demultiplexers 114 and 115 on a semiconductor substrate 111.
- At least one of the first phase modulation waveguide 112 and the second phase modulation waveguide 113 is the semiconductor optical modulator of the present invention.
- the first phase modulation waveguide 112 is connected to the optical multiplexer / demultiplexer 114 via a waveguide 116a, and is connected to the optical multiplexer / demultiplexer 115 via a waveguide 116b.
- the second phase modulation waveguide 113 is connected to the optical multiplexer / demultiplexer 114 via a waveguide 116c, and is connected to the optical multiplexer / demultiplexer 115 via a waveguide 116d.
- Upper electrodes are provided on the second n-type cladding layers of the first phase modulation waveguide 112 and the second phase modulation waveguide 113 (not shown).
- the first n-type cladding layer formed on the semiconductor substrate 111 is provided with electrodes (not shown).
- the substrate is a semiconductor substrate
- the first semiconductor optical modulator and the second semiconductor optical modulator are the first phase modulation waveguide and the second phase modulation.
- a waveguide is used
- the demultiplexing unit and the multiplexing unit are optical multiplexers / demultiplexers.
- the optical multiplexer / demultiplexer include an MMI coupler, a directional coupler, a Y-branch waveguide, and the like.
- the upper electrode include a traveling wave electrode and a lumped constant electrode.
- the semiconductor Mach-Zehnder optical modulator of this embodiment operates as follows. That is, first, when input light is input to the input end of the optical multiplexer / demultiplexer 114, the input light is demultiplexed and branched into two lights by the optical multiplexer / demultiplexer 114. The branched lights are introduced into the first phase modulation waveguide 112 and the second phase modulation waveguide 113, respectively. At this time, the phase of the branched light is changed based on the voltage applied to the first phase modulation waveguide 112 and the second phase modulation waveguide 113 by the upper electrode and the electrode (not shown). Modulated. The two modulated lights are multiplexed by the optical multiplexer / demultiplexer 115 and output from the output terminal of the optical multiplexer / demultiplexer 115.
- the semiconductor Mach-Zehnder optical modulator 110 of this embodiment at least one of the first phase modulation waveguide 112 and the second phase modulation waveguide 113 is the semiconductor optical modulator of the present invention.
- Light propagation loss of input light can be reduced, and the electric field strength to the light modulation layer can be improved.
- the semiconductor Mach-Zehnder type optical modulator of this embodiment is highly efficient.
- at least one of the first phase modulation waveguide 112 and the second phase modulation waveguide 113 is the semiconductor optical modulator of the present invention.
- the semiconductor Mach-Zehnder optical modulator of this embodiment has high reliability.
- the semiconductor optical modulator of the present invention and the semiconductor Mach-Zehnder optical modulator of the present invention are highly efficient and highly reliable. Accordingly, the use of the semiconductor optical modulator of the present invention and the semiconductor Mach-Zehnder type optical modulator of the present invention includes, for example, an optical modulator of a transmitter for optical communication used in a trunk line system, a metro system, an access system, etc.
- the application is not limited, and it can be applied to a wide range of fields.
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Abstract
Description
基板上に、第1のn型クラッド層と、半導体光変調層と、p型クラッド層と、第2のn型クラッド層とが、前記順序で積層されることにより、導波路構造が形成され、
さらに、絶縁保護膜および電界緩和層を有し、
前記導波路構造の側面には、前記絶縁保護膜が配置され、
前記p型クラッド層と前記第2のn型クラッド層とが、前記電界緩和層を介して積層されており、
前記電界緩和層の不純物濃度が、前記p型クラッド層の不純物濃度および前記第2のn型クラッド層の不純物濃度より低いことを特徴とする。
基板上に、入力光を分波する光分波手段と、前記分波された光を変調する第1の半導体光変調器および第2の半導体光変調器と、前記第1の半導体光変調器および前記第2の半導体光変調器により変調された光を合波する合波手段とを備え、
前記第1の半導体光変調器および前記第2の半導体光変調器の少なくとも一方が、前記本発明の半導体光変調器であることを特徴とする。
図1に、本実施形態の半導体光変調器の一例の構成を示す。図示のとおり、この半導体光変調器10では、InP基板11上に、第1のn-InPクラッド層12と、多重量子井戸構造を有するアンドープ層(i層)13と、p-InPクラッド層14と、第2のn-InPクラッド層15とが、前記順序で積層され、ハイメサ導波路構造が形成されている。前記p-InPクラッド層14と前記第2のn-InPクラッド層15とが、電界緩和層16を介して積層されている。前記電界緩和層16の不純物濃度は、前記p-InPクラッド層14の不純物濃度、および前記第2のn-InPクラッド層15の不純物濃度より低く設定されている。前記導波路構造の表面(同図においては、左右の側面等)には、絶縁保護膜19が設けられている。矢印Aは、前記ハイメサ型導波路構造と前記絶縁保護膜19との境界を示す。本実施形態の半導体光変調器では、前記導波路構造を、ハイメサ型導波路構造とし、前記基板、前記第1のn型クラッド層、前記p型クラッド層および前記第2のn型クラッド層の材料を、InPとし、前記半導体光変調層を、多重量子井戸構造を有するアンドープ層(i層)としている。なお、前記第2のn-InPクラッド層15の上部には、電極との接合部における電気抵抗を低減するために、例えば、n型のInGaAsコンタクト層が設けられるが、本実施形態の半導体光変調器10では省略している。
図5(a)に、本実施形態の半導体光変調器の一例の構成を示す。同図において、図1と同一部分には、同一符号を付している。図示のとおり、この半導体光変調器50では、InP基板11上に、第1のn-InPクラッド層12と、アンドープ層(i層)13と、p-InPクラッド層14と、第2のn-InPクラッド層15とが、前記順序で積層され、ハイメサ導波路構造を有している。前記p-InPクラッド層14と前記第2のn-InPクラッド層15とが、電界緩和層56を介して積層されている。前記電界緩和層56は、前記第2のn-InPクラッド層15の不純物濃度より、不純物濃度が低いn-InPクラッド層(n--InPクラッド層)である。前記n--InPクラッド層56の不純物濃度は、前記p-InPクラッド層14の不純物濃度より低く設定されている。前記導波路構造の表面(図5(a)においては、左右の側面等)には、絶縁保護膜59が設けられている。これら以外は、実施形態1の半導体光変調器と同様である。
図8(a)に、本実施形態の半導体光変調器の一例の構成を示す。本実施形態の半導体光変調器は、前述の電界緩和層に代えて、前記p-InPクラッド層と前記第2のn-InPクラッド層との界面部分に、電界緩和領域を有し、前記第2のn-InPクラッド層の前記界面部分を含む領域が、前記電界緩和領域である。同図において、図1と同一部分には、同一符号を付している。図示のとおり、この半導体光変調器80では、InP基板11上に、第1のn-InPクラッド層12と、アンドープ層(i層)13と、p-InPクラッド層14と、第2のn-InPクラッド層85とが、前記順序で積層され、ハイメサ導波路構造を有している。前記導波路構造の表面(図8(a)においては、左右の側面等)には、絶縁保護膜89が設けられている。前記第2のn-InPクラッド層85の前記界面部分を含む領域が、電界緩和領域86である。図8(b)に示すように、前記電界緩和領域86の不純物濃度は、前記p-InPクラッド層14側に向かって低くなる勾配を有している。さらに、前記電界緩和領域86の半ば付近で、その不純物濃度が前記p-InPクラッド層14の不純物濃度より低くなっている。これら以外は、実施形態1または2の半導体光変調器と同様である。図8(b)において、図8(a)と同一部分には、同一符号を付している。本実施形態の半導体光変調器では、実施形態1の半導体光変調器により奏される効果に加えて、前述の半導体光変調器50と同様の効果を得ることが可能である。
図11に、本実施形態の半導体マッハツェンダー型光変調器の一例の構成を示す。図示のとおり、この半導体マッハツェンダー型光変調器110は、半導体基板111上に、第1の位相変調導波路112および第2の位相変調導波路113と、光合分波器114および115とを備える。前記第1の位相変調導波路112および前記第2の位相変調導波路113の少なくとも一方が、前記本発明の半導体光変調器である。前記第1の位相変調導波路112は、導波路116aを介して前記光合分波器114に接続され、導波路116bを介して前記光合分波器115に接続されている。前記第2の位相変調導波路113は、導波路116cを介して前記光合分波器114に接続され、導波路116dを介して前記光合分波器115に接続されている。前記第1の位相変調導波路112および前記第2の位相変調導波路113の第2のn型クラッド層には、上部電極が設けられている(図示せず)。前記半導体基板111に形成された第1のn型クラッド層には、電極が設けられている(図示せず)。本実施形態の半導体マッハツェンダー型光変調器では、基板を、半導体基板とし、第1の半導体光変調器および第2の半導体光変調器を、第1の位相変調導波路および第2の位相変調導波路とし、前記分波手段および前記合波手段を、光合分波器としている。前記光合分波器としては、例えば、MMIカプラ、方向性結合器、Y分岐導波路等があげられる。前記上部電極としては、例えば、進行波電極、集中定数型電極等があげられる。
10a、50a、60a 半導体光変調器のバンドダイアグラム
11 InP基板(基板)
12、42 第1のn-InPクラッド層(第1のn型クラッド層)
12a 第1のn-InPクラッド層のバンドダイアグラム
13、43 多重量子井戸構造を有するアンドープ層(i層:半導体光変調層)
13a アンドープ層(i層)のバンドダイアグラム
14、94、104 p-InPクラッド層(p型クラッド層)
14a p-InPクラッド層のバンドダイアグラム
15、85、105 第2のn-InPクラッド層(第2のn型クラッド層)
15a 第2のn-InPクラッド層のバンドダイアグラム
16 電界緩和層
16a 電界緩和層のバンドダイアグラム
19、49、59、89 絶縁保護膜
31 半導体光変調層に印加される電界
32 p-InPクラッド層と第2のn-InPクラッド層との間(電界緩和層)に印加される電界
56 電界緩和層(n--InPクラッド層)
56a n--InPクラッド層のバンドダイアグラム
66 電界緩和層(p--InPクラッド層)
66a p--InPクラッド層のバンドダイアグラム
76 電界緩和層
76a n--InPクラッド層
76b p--InPクラッド層
86、96、106 電界緩和領域
106a 第2のn-InPクラッド層の界面部分を含む領域
106b p-InPクラッド層の界面部分を含む領域
110 半導体マッハツェンダー型光変調器
111 半導体基板(基板)
112 第1の位相変調導波路(第1の半導体光変調器)
113 第2の位相変調導波路(第2の半導体光変調器)
114 光合分波器(光分波手段)
115 光合分波器(合波手段)
116a、116b、116c、116d 導波路
120、130 従来の半導体光変調器
120a、130a 従来の半導体光変調器のバンドダイアグラム
121、131 基板
122 n型半導体層
122a n型半導体層のバンドダイアグラム
123 光変調層(アンドープ層(i層))
123a 光変調層(アンドープ層(i層))のバンドダイアグラム
124 p型半導体層
124a p型半導体層のバンドダイアグラム
129 絶縁保護膜
132 第1のn-InPクラッド層
132a 第1のn-InPクラッド層のバンドダイアグラム
133 光変調層(i層)
133a 光変調層(i層)のバンドダイアグラム
135 第2のn-InPクラッド層
135a 第2のn-InPクラッド層のバンドダイアグラム
137 SIクラッド層
137a SIクラッド層のバンドダイアグラム
138 p型半導体領域
138a p型半導体領域のバンドダイアグラム
139 絶縁保護膜
151a、151b 電界のグラフ
152a、152b 光変調層に印加される電界
153a、153b ピーク電界
A、B、C 矢印
X1、X2 層方向座標
Claims (11)
- 基板上に、第1のn型クラッド層と、半導体光変調層と、p型クラッド層と、第2のn型クラッド層とが、前記順序で積層されることにより、導波路構造が形成され、
さらに、絶縁保護膜および電界緩和層を有し、
前記導波路構造の側面には、前記絶縁保護膜が配置され、
前記p型クラッド層と前記第2のn型クラッド層とが、前記電界緩和層を介して積層されており、
前記電界緩和層の不純物濃度が、前記p型クラッド層の不純物濃度および前記第2のn型クラッド層の不純物濃度より低いことを特徴とする半導体光変調器。 - 前記電界緩和層の不純物濃度が、1×1015~2×1017cm-3であることを特徴とする請求の範囲1記載の半導体光変調器。
- 前記電界緩和層が、前記p型クラッド層および前記第2のn型クラッド層より、不純物濃度の低いn型半導体層またはp型半導体層であることを特徴とする請求の範囲1または2記載の半導体光変調器。
- 前記電界緩和層の前記第2のn型クラッド層側が、前記p型クラッド層および前記第2のn型クラッド層より、不純物濃度の低いn型半導体層であり、
前記電界緩和層の前記p型クラッド層側が、前記p型クラッド層および前記第2のn型クラッド層より、不純物濃度の低いp型半導体層であることを特徴とする請求の範囲1または2記載の半導体光変調器。 - 前記電界緩和層に代えて、前記p型クラッド層と前記第2のn型クラッド層との界面部分に、電界緩和領域を有し、
前記電界緩和領域の不純物濃度が、前記p型クラッド層の不純物濃度の最高値および前記第2のn型クラッド層の不純物濃度の最高値より低いことを特徴とする請求の範囲1または2記載の半導体光変調器。 - 前記第2のn型クラッド層における前記電界緩和領域の不純物濃度が、前記p型クラッド層側に向かって低くなる勾配を有し、かつ、その最低値が、前記p型クラッド層の不純物濃度より低いことを特徴とする請求の範囲5記載の半導体光変調器。
- 前記p型クラッド層における前記電界緩和領域の不純物濃度が、前記第2のn型クラッド層側に向かって低くなる勾配を有し、かつ、その最低値が、前記n型クラッド層の不純物濃度より低いことを特徴とする請求の範囲5記載の半導体光変調器。
- 前記第2のn型クラッド層における前記電界緩和領域の不純物濃度が、前記p型クラッド層側に向かって低くなる勾配を有し、かつ、その最低値が、前記p型クラッド層の不純物濃度より低く、
前記p型クラッド層における前記電界緩和領域の不純物濃度が、前記第2のn型クラッド層側に向かって低くなる勾配を有し、かつ、その最低値が、前記n型クラッド層の不純物濃度より低いことを特徴とする請求の範囲5記載の半導体光変調器。 - 前記導波路構造が、ハイメサ導波路構造またはリッジ導波路構造であることを特徴とする請求の範囲1から8のいずれか一項に記載の半導体光変調器。
- 基板上に、入力光を分波する光分波手段と、前記分波された光を変調する第1の半導体光変調器および第2の半導体光変調器と、前記第1の半導体光変調器および前記第2の半導体光変調器により変調された光を合波する合波手段とを備え、
前記第1の半導体光変調器および前記第2の半導体光変調器の少なくとも一方が、請求の範囲1から9のいずれか一項に記載の半導体光変調器であることを特徴とする半導体マッハツェンダー型光変調器。 - さらに、上部電極を備え、
前記上部電極が、進行波電極であることを特徴とする請求の範囲10記載の半導体マッハツェンダー型光変調器。
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JP5747004B2 (ja) * | 2012-08-22 | 2015-07-08 | 株式会社フジクラ | 光導波路素子 |
US20160036532A1 (en) * | 2013-03-15 | 2016-02-04 | Nec Corporation | Optical modulator, optical transmitter, optical transmission/reception system, and control method for optical modulator |
WO2021013960A1 (en) * | 2019-07-24 | 2021-01-28 | Rockley Photonics Limited | Electro-optic modulator |
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JPH02272785A (ja) * | 1989-03-03 | 1990-11-07 | American Teleph & Telegr Co <Att> | 半導体デバイス |
JP2000066156A (ja) * | 1998-08-25 | 2000-03-03 | Mitsubishi Electric Corp | マッハツェンダ型光変調器 |
WO2004081638A1 (ja) * | 2003-03-11 | 2004-09-23 | Nippon Telegraph And Telephone Corporation | 半導体光変調器 |
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JP2751802B2 (ja) | 1993-09-30 | 1998-05-18 | 日本電気株式会社 | 半導体光変調装置 |
JP2002174801A (ja) * | 2000-12-07 | 2002-06-21 | Oki Electric Ind Co Ltd | 半導体光機能装置 |
US20090050933A1 (en) * | 2005-01-28 | 2009-02-26 | Nec Corporation | Semiconductor light-receiving device and method for manufacturing the same |
JP4141451B2 (ja) | 2005-03-08 | 2008-08-27 | 日本電信電話株式会社 | 半導体光変調器 |
WO2008029915A1 (fr) * | 2006-09-08 | 2008-03-13 | The Furukawa Electric Co., Ltd. | Dispositif d'émission de lumière à semiconducteur et son procédé de fabrication |
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JPH02272785A (ja) * | 1989-03-03 | 1990-11-07 | American Teleph & Telegr Co <Att> | 半導体デバイス |
JP2000066156A (ja) * | 1998-08-25 | 2000-03-03 | Mitsubishi Electric Corp | マッハツェンダ型光変調器 |
WO2004081638A1 (ja) * | 2003-03-11 | 2004-09-23 | Nippon Telegraph And Telephone Corporation | 半導体光変調器 |
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