JP5947743B2 - Semiconductor polarization control element - Google Patents

Description

  The present invention relates to a semiconductor polarization control element, and more particularly to a waveguide type semiconductor polarization control element capable of controlling an arbitrary polarization state at high speed.

  High-speed polarization control is a technology that plays an important role in an optical communication system. For example, in a single-mode fiber used in normal long-distance optical communications, the polarization state of light changes in a complicated manner with time, so when connecting to an optical integrated circuit having polarization dependence, the polarization dependence loss (PDL) is a problem. In addition, in polarization multiplexing transmission in which an optical modulation signal is placed on each orthogonal polarization, the signal on each orthogonal polarization is accurate unless the polarization state that randomly varies on the optical receiver side is analyzed and controlled at high speed. Cannot be received. Furthermore, polarization mode dispersion (PMD) accompanying an increase in optical transmission speed cannot be ignored. In view of these backgrounds, a high-speed polarization controller capable of infinite tracking has recently been proposed (for example, Patent Document 1).

  The polarization controller capable of infinite tracking mainly has an electro-optic effect typified by lithium niobate (LN), which converts incident polarized light into target emitted polarized light by mechanically rotating a rotating wave plate. There is a waveguide type using a crystal as a substrate material. The former uses, for example, a quarter-wave plate and a half-wave plate whose phase differences between two orthogonal orthogonal polarization axes are π / 2 and π, respectively. A half-wave plate and a quarter-wave plate are sequentially arranged, and by rotating and adjusting the axial direction of each wave plate, it can be converted into an arbitrary output polarized light. The latter is superior in that the polarization can be controlled at a higher speed (MHz or higher) than the former of the mechanical control because the electro-optic effect utilizing the piezoelectricity of the crystal is used.

Japanese Patent No. 4113877 Japanese Patent No. 2646558 JP-A-63-1118709

Optics letters Vol. 11, No. 1, pp. 39-41, Suwat Thaniyavarn

  FIG. 2 is a schematic cross-sectional view of an X-axis cut LN polarization control element (Z-axis waveguide formation). The voltage for rotating the polarization in a state where a constant bias voltage is applied to the electrode P in the figure. Applied to the electrode R to control the polarization. Here, the polarization is controlled by utilizing the birefringence control of the medium by the primary electro-optic (Pockels) effect. Details thereof will be described below.

  In an LN crystal, when an electric field is applied in the X-axis direction and light is propagated in the Z-axis direction, the refractive index ellipsoid of the medium is expressed as follows.

This equation is illustrated as shown in FIG. That is, when no voltage is applied, the refractive index ellipsoid on the XY plane is a perfect circle (isotropic crystal), whereas the refractive index ellipsoid distorts the perfect circle by applying an electric field (an anisotropic crystal). ) Further, the main axis is inclined 45 °. This is equivalent to a state in which the wave plate is tilted by 45 °. In this state, for example, if a TE polarized wave that is horizontal to the crystal plane is incident on the medium and an appropriate voltage value is applied, the polarized wave is changed from the TE mode. TM mode (polarized light in the vertical direction of the substrate) can be converted. However, since the optical waveguide of LN formed by titanium (Ti) diffusion has structural anisotropy in the waveguide itself, unless the structural anisotropy is controlled by any method, the above-described electro-optic effect is caused. TE-TM mode conversion cannot be performed efficiently (low voltage control). The following expression is an expression that expresses the ratio of polarization conversion to the TM mode with respect to TE polarized light incidence based on the mode coupling theory.

Here, κ is a coupling coefficient and represents the ease of power transfer between the TE mode and the TM mode. P ₀ is the total optical output power, δβ is a propagation constant difference (birefringence) between TE and TM, z is a variable in the propagation direction, α is an overlap of light and electric field (1 ≧ α ≧ 0), and r is Pockels. constant, the n _o medium refractive index, V is the applied voltage, Gap, is the distance between electrodes.

  From the above equation, in order to increase the TM mode conversion efficiency, it is necessary to decrease δβ or increase κ. In the case of an LN device, it is difficult to make δβ zero when there is no bias due to the above-described birefringence on the waveguide structure. Therefore, for example, as shown in FIG. 2 (Non-Patent Document 1), an appropriate bias voltage is applied to the electrode P, and a substrate horizontal direction electric field is applied to the waveguide, whereby a propagation constant difference δβ between TE and TM is applied. Is set to zero. However, since Gap2 in the figure requires a large interval of> 10 μm, there is a problem that an applied voltage value for obtaining a desired electric field intensity becomes high (20 V or more). Further, the Pockels constant r of LN contributing to polarization conversion is never a large value of 3.4 pm / V, and the gap interval of Gap1 shown in FIG. There is a problem that the voltage value applied to the electrode R necessary for wave rotation also becomes high (7 V for an electrode length of 1 cm). As a result, when the polarization is controlled with a low voltage value, the length of the voltage application region needs to be further increased, and the device size becomes larger and the lengthening becomes longer. Complex voltage control is also required. A method for reducing the voltage by reducing the LN thickness and providing a back electrode has been proposed (for example, Patent Document 2), but a complicated device structure is required and greatly reduced. Since it is difficult to reduce the voltage, problems still remain in reducing the voltage and reducing the size of the polarization control element made of the LN material.

  The present invention has been made in view of such problems, and aims to realize a high-speed polarization control element with a simple configuration by realizing a waveguide-type polarization control element with low voltage control and small size. To do.

  In order to achieve the above object, in the polarization control device according to the first aspect of the present invention, at least a first p-cladding layer and a second p-cladding layer are provided on the semi-insulating substrate surface of the zincblende semiconductor crystal. It has a structure in which guided light is sandwiched from the horizontal direction of the substrate, and at least a first n-clad layer is provided above the waveguide layer. Further, electrodes A and B are provided on the p-cladding layer so that a horizontal electric field is applied between the p-cladding layers, and the electrode C is arranged so that a substrate vertical electric field is applied to the waveguide layer. It was decided to be provided on the n-clad layer.

  In the polarization control element according to the second aspect of the invention, at least the first p-clad layer and the n-clad layer sandwich the guided light from the substrate horizontal direction on the semi-insulating substrate surface of the zincblende semiconductor crystal. At least a second p-cladding layer is provided on the waveguide layer. Furthermore, electrodes A and B are provided on the first p-cladding layer and the n-cladding layer, respectively, so that a horizontal electric field is applied between the first p-cladding layer and the n-cladding layer, and to the waveguide layer. The electrode C is provided on the second p-clad layer so that the substrate vertical direction electric field is applied.

  The above means will be described in more detail with reference to FIG. In the case of a zinc blende structure crystal such as InP, TE-TM polarization conversion can be performed on the same principle as the LN by applying a voltage in a direction equivalent to the [110] direction. Specifically, for example, when a (100) plane substrate is used, a waveguide stripe is formed in a direction equivalent to the [011] direction, and a substrate horizontal electric field is applied to the waveguide. As shown, the refractive index ellipsoid of the waveguide cross section is tilted by 45 ° and distorted. Further, it is known that the propagation constant difference between TE and TM changes when an electric field is applied to the waveguide in the direction perpendicular to the substrate (100). In other words, as with the LN device, by providing a mechanism that can independently control the applied voltage values in the vertical and horizontal directions with respect to the waveguide, any polarization control element can be used even in a zinc blende type semiconductor. It becomes feasible.

  One of the main advantages of producing the polarization control element using zinc-blende crystal such as InP is that it is locally high to the core layer by adopting a pin structure and a pin structure. The point which can apply a voltage is mentioned. In the case of an insulating material such as LN, the electrode spacing determines the magnitude of the electric field strength, whereas in the pin structure or the like, the i-layer width (for example, Gap3) determines the electric field strength. That is, in Gap1, an electrode interval of at least 10 μm or more was required for the electrode structure, whereas in Gap3, it was possible to reduce the distance to 2 μm or less. Can be obtained. In addition, since the material dielectric constant of the semiconductor is about 1/3 of LN, even if the gap is narrowed, an increase in device capacity can be suppressed. Therefore, it can be said that the material is useful for high-speed polarization control. .

  Furthermore, since compound semiconductors such as InP are easier to process in waveguide mesa and ion implantation / thermal diffusion of atoms than LN, the conductive clad layer metalized like the p-type clad layer in FIG. Since it acts as an electrode, the interaction between light and electric field (the value of overlap α described above) is large. For example, when adjusting δβ, an electric field in the horizontal direction of the substrate is applied to the waveguide. At this time, the light-electric field overlap α is approximately 0.5 for the planar electrode structure LN. In this case, it can be 0.9 or more.

  As described above, when the value of κ of the device according to the present invention is estimated from the structural and material viewpoints, it is expected that the coupling efficiency will be improved by 7 times compared to the case of LN, and δβ is adjusted. The TE-TM phase shift is expected to improve the shift efficiency by 10 times compared to the LN case. That is, it can be expected that the drive voltage of the element is reduced and the size is reduced as compared with the existing LN polarization control element.

  According to the present invention, by using an InP-based material that is superior in terms of strong electric field confinement by a pn junction, strong interaction between light and electricity, and the like, an electric field control type polarization control device is manufactured. A small and low driving voltage operation can be realized. This provides a new transmission system, an ultra-compact polarization control system, and the like in which a polarization control element that compensates for a temporal change in polarization, which is a problem in an optical communication system, is integrated with other small semiconductor devices. .

It is a graph which shows the change of the refractive index ellipsoid by electric field application. It is the schematic of the conventional LN polarization control element. It is sectional drawing of the semiconductor polarization control element concerning Example 1 of this invention. It is a top view of the semiconductor polarization control element concerning Example 1 of the present invention. It is a top view of the polarization control element which connected the semiconductor polarization control element concerning Example 1 of this invention in series. It is sectional drawing of the semiconductor polarization control element concerning Example 2 of this invention. It is a top view of the semiconductor polarization control element concerning Example 2 of this invention. It is a top view of the polarization control element which connected the semiconductor polarization control element concerning Example 2 of this invention in series. It is sectional drawing at the time of replacing the clad layer of the semiconductor polarization control element concerning Example 1 of this invention with a MOS structure.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments.

[Example 1]
FIG. 3 is a cross-sectional view of the polarization control element of this embodiment. In this embodiment, a p-i-p structure is adopted in the horizontal direction of the substrate so that an electric field is applied in the horizontal direction of the substrate, and at the same time, an n-type cladding layer is introduced so that an electric field can be applied independently in the vertical direction of the substrate. It was deposited immediately above the waveguide to form a pin structure. Note that, instead of the n-type cladding layer, a metal-oxide-semiconductor (MOS) structure with an insulating film (SiO ₂ or the like) 23 interposed therebetween as shown in FIG. The utility of the present invention is not lost because an electric field can be applied. Crystal growth was performed by a metal organic chemical vapor deposition (MOVPE) method suitable for a crystal regrowth process, and a (100) plane-oriented semi-insulating (SI) substrate was used as a substrate crystal. For example, even when a substrate equivalent to the (011) plane orientation is used, when the electrode Z is grounded, if the respective voltages applied to the electrodes X and Y are reversed to those in the case of the (100) substrate, this The usefulness of the embodiment is not lost. The bulk core layer is a non-doped layer, and its band gap wavelength is determined so that the electro-optic effect is effective at the operating light wavelength and the light absorption is not a problem. For example, in the case of a polarization control device in the 1.55 μm band, the core layer is formed of an InGaAsP layer having an emission wavelength of 1.2 μm. Of course, no absorption occurs in the wavelength region, and the emission wavelength is 1. It is clear that there is no problem even if InGaAsP or InGaAlAs of 5 μm or less is used. It is obvious that the usefulness of the present invention is not lost even if the core layer is not a bulk type, for example, a multiple quantum well (MQW) type.

After depositing a non-doped InP clad layer 8 on the SI-InP substrate 7 by 0.5 μm, the core layer 9 (0.5 μm), the non-doped InP clad layer 10 and the n-type InP clad layer 12 (1.5 μm), Crystal growth was performed in the order of the n-type InGaAs electrode contact layer 13 (0.2 μm). The doping concentration of these cladding layers is desirably 5 × 10 ¹⁷ cm ⁻³ or more so that a voltage drop is efficiently generated in the core layer. For example, the doping concentration of the n-type InP cladding layer is 1 × 10 ¹⁸ cm ^−3, and the doping concentration of the n-type InGaAs electrode contact layer is 5 × 10 ¹⁸ cm ⁻³ . Note that there is no problem as long as the layer laminated for the electrode contact can secure sufficient conductivity. Therefore, the semiconductor doped with the n-type impurity is not limited to InGaAs, and for example, InGaAsP may be used. Subsequently, in order to make the polarization control element function as an optical waveguide, etching is performed until the n-type InP cladding layer is exposed by dry etching using, for example, a SiO ₂ mask having a waveguide shape in the [011] direction. Subsequently, the non-doped InGaAsP core layer is exposed by wet etching using a mixed solution of hydrochloric acid and phosphoric acid to produce a mesa structure (for example, the core width is 1.6 μm).

After forming the mesa structure, the region other than the p-clad region shown in FIG. 4 was covered with a SiO ₂ mask 18 and Zn was ion-implanted to make the non-doped InGaAsP region with an open mask window p-type. It is obvious that the p-type method is not limited to ion implantation, and there is no problem even with thermal diffusion in a Zn atmosphere, for example. As with the n-type, at least a depth of 0.2 μm from the semiconductor surface was set to a doping concentration of 5 × 10 ¹⁸ cm ⁻³ or more so as to ensure sufficient conductivity.

  After forming the linear optical waveguide 19 including the p-i-n layer and the p-i-p layer, the mesa side was covered with polyimide 14 in order to stably form the electrode X. Thereafter, for example, an AuGeNi alloy was deposited on the n-type InGaAs electrode contact layer, and an AuZnNi alloy, for example, was deposited on the p-type InGaAsP layer, and then heat treatment was performed using a sintering furnace. Thereafter, 1 μm of Au was deposited through Ti for improving adhesiveness.

The manufactured element is chipped as shown in FIG. 4 to complete a one-stage polarization control element. In order to realize an arbitrary rotation axis angle and retardation in the polarization controller, appropriate voltages are applied to the electrodes X and Y. The phase difference and the rotation angle are determined by the magnitude of the applied voltage and the ratio in the [100] and [011] directions. When the electric field in the [100] direction is E ₁₀₀ and the electric field in the [011] direction is E ₀₁₁ , the rotation angle θ of the crystal axis is
θ = (1/2) · Tan ⁻¹ (E ₁₀₀ / E ₀₁₁ )
It becomes. Further, the thickness of the wave plate is proportional to (E ₁₀₀ ² + E ₀₁₁ ² ) ^1/2 .

  Furthermore, in order to fix the polarization state against random fluctuations in the polarization state, an infinite follow-up type polarization controller is required, and the polarization controller of the one-stage configuration can be realized with low voltage drive. Since it is difficult, a configuration in which the polarization controllers are installed in multiple stages in series is effective (for example, Patent Document 3). FIG. 5 shows a configuration in which at least three of the polarization controllers of this embodiment are provided in series in multiple stages, and the p-doping layers at each stage are formed via non-doped layers, respectively. Thereby, electrical separation between the conductive layers is possible.

  Thus, according to the present invention, by using an InP-based material that is superior in terms of strong electric field confinement by a pn junction, strong interaction between light and electricity, etc., an electric field control type polarization control device is manufactured, A small and low driving voltage operation of the device can be realized.

  Here, it is obvious that the usefulness of the substrate material does not change even when the substrate material has the same crystal structure other than InP, for example, GaAs, GaP, ZnS, or ZnSe.

  In the present embodiment, the light modulation element corresponding to the 1.55 μm wavelength band is used, but an element corresponding to the 1.3 μm wavelength band may be used.

  For example, if GaAs is used, it can respond to a wavelength range of 0.6 to 1.3 μm.

[Example 2]
FIG. 6 is a cross-sectional view of the polarization control element of this embodiment. In this embodiment, a p-i-n structure is employed in the horizontal direction of the substrate so that an electric field is applied in the horizontal direction of the substrate, and at the same time, a p-type cladding layer is introduced so that an electric field can be applied independently in the vertical direction of the substrate. It was deposited immediately above the waveguide to form a pip structure. Even if a metal-oxide-semiconductor (MOS) structure with an insulating film (SiO ₂ or the like) interposed therebetween is used instead of the p-type cladding layer directly above the waveguide, for example, as shown in FIG. Therefore, the utility of the present invention is not lost. Crystal growth was performed by a metal organic chemical vapor deposition (MOVPE) method suitable for a crystal regrowth process, and a (100) plane-oriented semi-insulating (SI) substrate was used as a substrate crystal. For example, even when a substrate equivalent to the (011) plane orientation is used, if the respective voltages applied to the electrode R and the electrode P are reversed to those in the case of the (100) substrate, the usefulness of this embodiment is lost. I will not. The bulk core layer is a non-doped layer, and its band gap wavelength is determined so that the electro-optic effect is effective at the operating light wavelength and the light absorption is not a problem. For example, in the case of a polarization control device in the 1.55 μm band, the core layer is formed of an InGaAsP layer having an emission wavelength of 1.2 μm. Of course, no absorption occurs in the wavelength region, and the emission wavelength is 1. It is clear that there is no problem even if InGaAsP or InGaAlAs of 5 μm or less is used. It is obvious that the usefulness of the present invention is not lost even if the core layer is not a bulk type, for example, a multiple quantum well (MQW) type.

After depositing a non-doped InP clad layer 8 on the SI-InP substrate 7 by 0.5 μm, the core layer 9 (0.5 μm), the non-doped InP clad layer 10 and the p-type InP clad layer 20 (1.5 μm), Crystal growth was performed in the order of the p-type InGaAs electrode contact layer 21 (0.2 μm). The doping concentration of these cladding layers is desirably 5 × 10 ¹⁷ cm ⁻³ or more so that a voltage drop is efficiently generated in the core layer. For example, the doping concentration of the p-type and InP cladding layers is 5 × 10 ¹⁸ cm ^−3, and the doping concentration of the p-type InGaAs electrode contact layer is 1 × 10 ¹⁹ cm ⁻³ . Note that the layer laminated for the electrode contact is not a problem as long as sufficient conductivity can be ensured. Therefore, the semiconductor doped with the p-type impurity is not limited to InGaAs, and for example, InGaAsP may be used. Subsequently, in order to make the polarization control element function as an optical waveguide, etching is performed until the p-type InP cladding layer is exposed by dry etching using, for example, a SiO ₂ mask whose waveguide shape is imitated in the [011] direction. Subsequently, the non-doped InGaAsP core layer is exposed by wet etching using a mixed solution of hydrochloric acid and phosphoric acid to produce a mesa structure (for example, the core width is 1.6 μm).

After forming the mesa structure, the region other than the p-clad region shown in FIG. 7 was covered with an SiO ₂ mask, and Zn was ion-implanted to make the non-doped InGaAsP region with an open mask window p-type. It is obvious that the p-type method is not limited to ion implantation, and there is no problem even with thermal diffusion in a Zn atmosphere, for example. Subsequently, similarly, a region other than the n-clad region shown in FIG. 7 was covered with an SiO ₂ mask, and Si was ion-implanted to make the non-doped InGaAsP region having an open mask window n-type. In order to ensure sufficient conductivity, at least both p and n-type layers have a doping concentration of 5 × 10 ¹⁸ cm ⁻³ or more at a depth of 0 to 2 μm from the semiconductor surface.

  After forming the linear optical waveguide including the p-i-n layer and the p-i-p layer, the side of the mesa was covered with polyimide in order to stably form the electrode X. Thereafter, for example, an AuGeNi alloy was deposited on the n-type InGaAs electrode contact layer, and an AuZnNi alloy, for example, was deposited on the p-type InGaAsP layer, and then heat treatment was performed using a sintering furnace. Thereafter, 1 μm of Au was deposited through Ti for improving adhesiveness.

The manufactured element is chipped as shown in FIG. 7 to complete a one-stage polarization control element. In order to realize an arbitrary rotation axis angle and retardation in the polarization controller, appropriate voltages are applied to the electrodes X, Y, and Z. The phase difference and the rotation angle are determined by the magnitude of the applied voltage and the ratio in the [100] and [011] directions. When the electric field in the [100] direction is E ₁₀₀ and the electric field in the [011] direction is E ₀₁₁ , the rotation angle θ of the crystal axis is
θ = (1/2) · Tan ⁻¹ (E ₁₀₀ / E ₀₁₁ )
It becomes. Further, the thickness of the wave plate is proportional to (E ₁₀₀ ² + E ₀₁₁ ² ) ^1/2 . In the case of a half-wave plate, the maximum voltage required to apply an electric field in the [100] direction is V ₀ , and the maximum voltage required to apply an electric field in the [011] direction is Vπ / Assuming 2, the voltage applied to each electrode shown in the figure is
(Electrode X) V _X = V ₀ cos (2θ) + Vπ / 2sin (2θ) + V _b
(Electrode Y) V _Y = 0
(Electrode Z) V _Z = V ₀ cos (2θ) −Vπ / 2sin (2θ) −V _b
Note that V _Z <V _X is satisfied because the device is driven under a reverse bias voltage. Here, V _b is a bias voltage necessary to make δβ zero. In the study in this example, V ₀ = 6V, Vπ / 2 = 4V, and V _b = 10V.

  Furthermore, in order to fix the polarization state against random fluctuations in the polarization state, an infinite follow-up type polarization controller is required, and the polarization controller of the one-stage configuration can be realized with low voltage drive. Since it is difficult, a configuration in which the polarization controllers are installed in multiple stages in series is effective (for example, Patent Document 3). In the upper part of FIG. 8, at least three of the polarization controllers of this embodiment are provided in series in multiple stages, and the adjacent doped layers are formed to be pnp... Via non-doped layers. . This facilitates electrical separation between the conductive layers. Even if the doping layers are not alternately replaced as described above, there is no problem even if all or part of the non-doped regions between the respective stages are made p-type or n-type as shown in the lower part of FIG. It is clear.

  Thus, according to the present invention, by using an InP-based material that is superior in terms of strong electric field confinement by a pn junction, strong interaction between light and electricity, etc., an electric field control type polarization control device is manufactured, A small and low driving voltage operation of the device can be realized.

  Here, it is obvious that the usefulness of the substrate material does not change even when the substrate material has the same crystal structure other than InP, for example, GaAs, GaP, ZnS, or ZnSe.

  In the present embodiment, the light modulation element corresponding to the 1.55 μm wavelength band is used, but an element corresponding to the 1.3 μm wavelength band may be used.

  For example, if GaAs is used, it can respond to a wavelength range of 0.6 to 1.3 μm.

1 LN
2 Ti diffusion waveguide 3 Buffer layer 4 Electrode R
5 Electrode P
6 Ground electrode 7 Semi-insulating InP substrate 8 i-clad layer 9 i-core layer 10 i-clad layer 11 p-clad layer 12 n-clad layer 13 n-contact layer 14 polyimide 15 X electrode 16 Y electrode 17 Z electrode 18 SiO ₂ mask 19 Optical waveguide 20 p-cladding layer 21 p-contact layer 22 n-cladding layer 23 Insulating film

Claims (9)

  A polarization control element using a zinc blende type semiconductor crystal, on a semi-insulating substrate, at least one pair of a first p-cladding layer, a waveguide layer, and a second p-cladding layer, And the first p-cladding layer and the second p-cladding layer have a structure in which the waveguide layer is sandwiched in the horizontal direction of the substrate, and at least one first clad layer is disposed on the waveguide layer. A semiconductor polarization control element having one n-clad layer.   A polarization control element using a zinc blende type semiconductor crystal, on a semi-insulating substrate, at least one pair of a first p-clad layer, a waveguide layer, and a first n-clad layer The first p-cladding layer and the first n-cladding layer have a structure in which the waveguide layer is sandwiched in the horizontal direction of the substrate, and at least one first clad layer is disposed on the waveguide layer. A semiconductor polarization control element comprising two p-cladding layers.   2. The semiconductor polarization control element according to claim 1, wherein an electrode X is applied so that an electric field is applied in a horizontal direction of the substrate between the first p-cladding layer and the second p-cladding layer. Z is provided on each of the first p-cladding layer and the second p-cladding layer, and the electrode Y is disposed on the first p-cladding layer so that an electric field is applied to the waveguide layer in a direction perpendicular to the substrate. A semiconductor polarization control element provided on an n-cladding layer.   3. The semiconductor polarization control element according to claim 2, wherein an electrode X is applied so that an electric field is applied in a horizontal direction of the substrate between the first p-clad layer and the first n-clad layer. Z is provided on each of the first p-cladding layer and the first n-cladding layer, and the electrode Y is disposed on the second p so that an electric field is applied to the waveguide layer in a direction perpendicular to the substrate. A semiconductor polarization control element provided on a cladding layer.   A polarization control element using a zinc blende type semiconductor crystal, on a semi-insulating substrate, at least one pair of a first p-cladding layer, a waveguide layer, and a second p-cladding layer, And the first p-cladding layer and the second p-cladding layer have a structure in which the waveguide layer is sandwiched in the horizontal direction of the substrate, and at least one insulating layer is provided on the waveguide layer. A semiconductor polarization control element comprising a film and an electrode Y on each of the at least one insulating film.   A polarization control element using a zinc blende type semiconductor crystal, on a semi-insulating substrate, at least one pair of a first p-clad layer, a waveguide layer, and a first n-clad layer And the first p-cladding layer and the first n-cladding layer have a structure in which the waveguide layer is sandwiched in the horizontal direction of the substrate, and at least one insulating layer is provided on the waveguide layer. A semiconductor polarization control element comprising a film and an electrode Y on each of the at least one insulating film.   A polarization control element using a zinc blende type semiconductor crystal, comprising at least three of the semiconductor polarization control elements according to claim 1 or 5 or 6 on a semi-insulating substrate, The semiconductor polarization, wherein the at least three semiconductor polarization control elements are arranged in series so that the respective waveguide layers of the at least three semiconductor polarization control elements form the same waveguide. Control element.   A polarization control element using a zinc blende-type semiconductor crystal, comprising at least three semiconductor polarization control elements according to claim 2 on a semi-insulating substrate, wherein the at least three semiconductor polarization control elements are provided. Each of the waveguide layers of the control element forms the same waveguide, and the first p-clad layer and the first of the two adjacent semiconductor polarization control elements of the at least three semiconductor polarization control elements The semiconductor polarization control element is characterized in that the at least three semiconductor polarization control elements are arranged in series such that the n clad layers are alternately arranged.   A polarization control element using a zinc blende-type semiconductor crystal, comprising at least three semiconductor polarization control elements according to claim 2 on a semi-insulating substrate, wherein the at least three semiconductor polarization control elements are provided. Each of the waveguide layers of the control element forms the same waveguide, and the first p-clad layer and the first of the two adjacent semiconductor polarization control elements of the at least three semiconductor polarization control elements The at least three semiconductor polarization control elements are arranged in series so that the n-cladding layers are arranged in the same direction, and between the first p-cladding layers of the two adjacent semiconductor polarization control elements. And a second p-clad layer is disposed between the first n-clad layers of the two adjacent semiconductor polarization control elements. .

Images