JP2010016241A - Light transmitting/receiving device and light transmission/reception system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a structure in a light transmitting/receiving device having a light-emitting section and a light-receiving section which controls polarized waves at high efficiency without requiring complicated manufacturing processes. <P>SOLUTION: The light-emitting section 120 and the light-receiving section 130 are formed in close proximity to a substrate 10. The light-emitting section 120 and the light-receiving section 130 are driven mutually independently. At the top of the light-receiving section 130, an impurity diffused region 139 is formed, and the light-receiving section 130 can receive light at high efficiency. A microstructure necessary to control polarized waves can be formed on surfaces of the light-emitting section 120 and the light-receiving section 130. Thereby a light transmitting/receiving device that can control polarized waves and at high efficiency can be obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical transmission / reception device and an optical transmission / reception system in which a light emitting unit and a light receiving unit are formed on the same substrate.

  In recent years, along with rapid computerization, the data communication volume in the backbone communication network has increased rapidly, and at the same time, the data communication volume in consumer devices and terminals has also increased rapidly, and it is necessary to increase the communication speed and increase the communication capacity. It has been. For this reason, low-speed communication methods using electrical signals have been used for consumer devices, and optical signals such as semiconductor lasers that are light emitting elements and photodiodes that are light receiving elements are used as electrical signals for backbone communication networks. An optical communication technique using an element to be converted has been used. However, recently, there is a tendency to widely disseminate optical communication technology used only in the backbone communication network to devices that use a low-speed communication method using electrical signals such as consumer devices.

  However, consumer devices and the like have a strong demand for cost reduction compared to backbone communication networks and the like. For this reason, using light-emitting elements and light-receiving elements that are very fast with a single channel in consumer equipment and the like makes such light-emitting elements and light-receiving elements very expensive, and increases the sophistication of peripheral systems. It is not suitable because it is necessary. For this reason, it has been studied to increase the communication capacity of consumer equipment by multiplexing wavelengths or polarized waves although it is relatively slow with a single element. Since communication used for consumer devices and the like is relatively short distance, and consumer devices and the like need to be small, it is necessary to use a surface emitting laser (VCSEL) as a communication light source. Expected. In addition, WDM (Wavelength Division Multiplexing) using a plurality of different wavelengths is generally used as a signal multiplexing method. However, depending on the structure of the surface emitting laser and the characteristics of the manufacturing method, the WDM (Wavelength Division Multiplexing) is different in a monolithic manner. It is very difficult to generate a wavelength.

  On the other hand, in the polarization multiplexing method that simultaneously transmits optical signals of different polarization states using a single optical fiber, the number of channels can be increased by the number of polarization states, and communication can be performed by the number of polarization states. The capacity can be increased. The polarization multiplexing method can be used even if the wavelength is the same, and if it can control the polarization of the output light of the surface emitting laser, it can be very expected as an inexpensive and high-speed multiplex communication means. The following example is described in Patent Document 1 as means for generating a polarization multiplexed optical signal. As shown in FIG. 11 (a), the horizontally polarized wave 1001 and the vertically polarized wave 1002, which are the outputs of the two laser devices, and the polarization maintaining optical fiber 1004 are coupled to each other so that the two polarization maintaining optical fibers are mutually offset. The waves are connected to the input side of the polarization multiplexer 1000 so that the directions are different by 90 degrees. A signal extracted from the polarization maintaining optical fiber 1004 connected to the output side of the polarization multiplexer 1000 includes an orthogonal polarization multiplexed light 1003 including optical signals in two polarization states whose polarizations are 90 degrees different from each other. Become.

In order to realize the configuration shown in Patent Document 1 with a monolithic structure using a surface emitting laser, it is necessary to integrate the light emitting element and the light receiving element on the same substrate. As means for integrating the light emitting element and the light receiving element, Patent Document 2 describes the following example. As shown in FIG. 11B, as an element constituting the optical transmission / reception device 1100, there is a method in which a light emitting unit 1101 and a light receiving unit 1102 are stacked and formed thereunder.
JP 2003-124913 A Japanese Patent Laid-Open No. 4-207079

  However, according to the conventional structure, since the light emitting elements are stacked on the light receiving element, there is a problem that the speed is reduced as the area of the light receiving element is increased. Further, in such a structure, a large step is generated between the surface of the light emitting element and the surface of the light receiving element, so that it is necessary to control the polarization of each element when performing high density integration. There is a problem that it becomes difficult to process a microstructure.

  An object of the present invention is to solve the above-described conventional problems and to realize an optical transmission / reception apparatus and an optical transmission / reception system capable of transmitting and receiving a polarization multiplexed optical signal with only a simple process with a small number of components.

  In order to solve the above problems, the present invention is configured to arbitrarily control the polarization direction of light transmitted from the light emitting unit of the optical transceiver and the polarization direction of light received by the light receiving unit.

  Specifically, the optical transmission / reception apparatus according to the present invention includes a light emitting unit and a light receiving unit on a substrate, and the light receiving unit is provided with a region where impurities are diffused at a high concentration.

  The optical transceiver of the present invention includes a semiconductor substrate, and at least one light emitting unit and light receiving unit formed on the semiconductor substrate. The light emitting unit and the light receiving unit each include a first reflecting mirror, an active layer, and a second reflecting mirror. The first reflecting mirrors are respectively disposed between the substrate and the active layer, and the active layers are respectively disposed between the first reflecting mirror and the second reflecting mirror. A region where impurities are diffused is provided in a part of the second reflecting mirror of the light receiving unit.

  With such a configuration, the light emitting unit and the light receiving unit are formed on the same substrate. In addition, since the reflecting mirror on the light receiving surface side of the light receiving unit is disordered by utilizing high-concentration impurity diffusion, the reflectance at the light receiving unit can be reduced, and as a result, the light receiving unit efficiently receives the received light. It can be often converted into an electrical signal.

  In the optical transceiver of the present invention, it is preferable that each of the first reflecting mirror and the second reflecting mirror is a semiconductor multilayer film.

  By adopting such a configuration, a very high reflectance can be obtained in the light emitting portion, so that a surface emitting laser having excellent characteristics can be realized. Further, in the light receiving portion, the reflectance is reduced by disordering the reflecting mirror on the light receiving surface side by impurity diffusion, and as a result, the light receiving efficiency can be increased.

  In the optical transceiver according to the present invention, it is preferable that the step between the surface of the light emitting unit and the surface of the light receiving unit is equal to or less than the wavelength of light emitted from the light emitting unit.

  By adopting such a configuration, the light emitting surface and the light receiving surface have the same height, and the manufacturing process can be simplified. Further, when combined with an optical system such as a lens, the light emitting unit and the light receiving unit can be easily combined with the optical system.

  In the optical transmission / reception apparatus of the present invention, it is preferable that at least one of the light emitting unit and the light receiving unit has a micro structure formed so that the interval is equal to or less than the emission wavelength of the light emitting unit.

  With such a configuration, it becomes possible to perform mode control and polarization control of the transmission light of the light emitting unit and the reception light of the light receiving unit, which is essential for realizing polarization multiplexing communication or an optical sensor. A control light transmission / reception device (an optical transmission / reception device whose polarization is controlled) can be realized with a monolithic structure.

  In the optical transceiver according to the present invention, it is preferable that the microstructure has a periodic structure.

  With such a configuration, it is possible to perform mode control and polarization control of the transmitted light of the light emitting unit and the received light of the light receiving unit using the photonic band gap etc. of the photonic crystal, and excellent polarization control An optical transceiver can be realized.

  In the optical transceiver according to the present invention, the microstructure is preferably formed of metal.

  By adopting such a configuration, it becomes possible to perform mode control and polarization control of the transmitted light of the light emitting unit and the received light of the light receiving unit utilizing the surface plasmon resonance effect observed in the metal film having a periodic structure, An excellent polarization control light transmitting / receiving apparatus can be realized.

  In the optical transceiver of the present invention, it is preferable that the microstructure is formed on at least one surface of the light emitting unit and the light receiving unit.

  With such a configuration, it is possible to realize mode control of transmission light of the light emitting unit, improvement in reception efficiency of reception light of the light receiving unit, and the like.

In the optical transceiver of the present invention, the semiconductor multilayer film is preferably made of Al _1-x Ga _x As, and the impurity is preferably Zn.

  By adopting such a configuration, the semiconductor multilayer film is disordered by the diffusion of Zn, so that the second reflecting mirror becomes a transparent material at the emission wavelength of the light emitting part, and as a result, the reception efficiency is improved at the light receiving part. Is feasible.

  The optical transmission / reception system of the present invention transmits a plurality of optical signals having different linear polarization directions using the optical transmission / reception apparatus.

  With this configuration, it is possible to realize a polarization multiplexed optical communication system, an optical sensor that detects the polarization dependence of an object, and the like.

  According to the optical transmission / reception apparatus according to the present invention, the bidirectional optical transmission / reception has a small number of components, can be easily implemented only by simple adjustment, and can transmit and receive a polarization multiplexed optical signal with high reliability. A system can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
An optical transceiver 101 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1A shows a cross-sectional configuration of the optical transceiver 101 according to the first embodiment. In the optical transceiver 101, the light emitting unit 120 transmits the transmitted light 102 and the light receiving unit 130 receives the received light 103. It has a configuration. FIG. 1B shows a surface configuration of the optical transceiver 101 according to the first embodiment. 2A to 2C show a cross-sectional configuration of a method for manufacturing the optical transceiver 101 of the present embodiment. 3 (a) and 3 (b) show the refractive index and the reflectance before the impurity diffusion region 139 is formed in the upper multilayer mirror 135 of the light receiving unit 130, respectively. ) Shows the refractive index and the reflectance after the impurity diffusion region 139 is formed in the upper multilayer reflector 135 of the light receiving unit 130, respectively.

  The optical transmission / reception apparatus 101 according to the present embodiment includes a light emitting unit 120 and a light receiving unit 130 formed on a substrate (semiconductor substrate) 10 as shown in FIG. Each of the light emitting unit 120 and the light receiving unit 130 includes independent electrodes and can be driven independently.

  Next, the structure, manufacturing method, and operating principle of the optical transceiver 101 of this embodiment will be described in detail with reference to FIGS. 1, 2, and 3. FIG. The optical transceiver 101 according to the first embodiment includes a light emitting unit 120 and a light receiving unit 130 on a substrate 10. As a structure constituting the light emitting unit 120, a base layer 121, a lower multilayer reflector (first reflector or second reflector) 122, a light emitting layer (active layer) 123, a current confinement layer 124, an upper multilayer reflector ( The second reflecting mirror or first reflecting mirror 125, the contact layer 126, the upper electrode 127, and the lower electrode 128, and as a structure constituting the light receiving unit 130, the base layer 131, the lower multilayer film reflecting mirror (first reflecting mirror) Or second reflecting mirror) 132, light receiving layer (active layer) 133, current constricting layer 124, upper multilayer reflecting mirror (second reflecting mirror or first reflecting mirror) 135, contact layer 136, upper electrode 137, lower electrode 138. And an impurity diffusion region 139. The current confinement layers 124 and 134 have current confinement regions 124a and 134a and oxide high resistance regions 124b and 134b, respectively.

Next, a structure formed by crystal growth will be described with reference to FIG. The substrate 10 is made of semi-insulating gallium arsenide (GaAs). The underlayer 21 is formed by crystal growth of n-type GaAs on the substrate 10. The lower multilayer mirror 22 is a multilayer film in which n-type Al _0.12 Ga _0.88 As layers and n-type Al _0.90 Ga _0.10 As layers are alternately stacked. Note that these semiconductor layers are doped with silicon as an n-type impurity. The film thickness of each semiconductor layer is λ / 4n (λ is the laser oscillation wavelength of the light emitting unit 120, and n is the refractive index of the medium), and is laminated for 34.5 periods.

Active layer 23, the well layer made of undoped GaAs _layer, a barrier layer made of Al _{0.30 Ga 0.70} As _layer, the lower spacer layer and the upper spacer layer made of Al _{0.30 Ga 0.70} As layer is laminated The number of well layers is three periods. The film thickness of the active layer 23 is λ / n.

The current confinement layer 24 includes a p-type Al _0.98 Ga _0.02 As layer, and is configured to replace a part of the p-type Al _0.90 Ga _0.10 As layer in the upper multilayer reflector 25. Has been.

The upper multilayer film reflector 25 is a multilayer film in which p-type Al _0.12 Ga _0.88 As layers and p-type Al _0.90 Ga _0.10 As layers are alternately stacked. Each semiconductor layer is doped with carbon as a p-type impurity. The thickness of each semiconductor layer is λ / 4n, and 9.5 periods are stacked.

The contact layer 26 is made of a p-type GaAs layer, and is doped with carbon as a p-type impurity at a high concentration of 1 × 10 ¹⁹ cm ⁻³ or more in order to reduce contact resistance with the electrode.

  The light emitting unit 120 includes a contact layer 126, an upper multilayer reflector 125, a current constricting layer 124, a light emitting layer 123, a lower multilayer reflector 122, and a part of the base layer 121 constituting the light emitter 120, as a base layer 121. Are separated from the periphery by a recess formed by selectively removing a part of the substrate 10 to be exposed and a recess formed by selectively removing a part of the substrate 10 to be exposed. It has a columnar structure of about 20 μm. An upper electrode 127 is formed so as to be in contact with part of the surface of the contact layer 126, and a lower electrode 128 is formed so as to be in contact with part of the exposed surface of the base layer 121.

  In the light receiving unit 130, the contact layer 136, the upper multilayer reflector 135, the current confinement layer 134, the light receiving layer 133, the lower multilayer reflector 132, and a part of the base layer 131 are disposed in the vicinity of the light emitting unit 120. It is separated from the periphery by a recess formed by selectively removing the exposed portion until it is exposed and a recess formed by selectively removing a portion of the substrate 10 until it is exposed. An upper electrode 137 is formed so as to be in contact with a part of the contact layer 136, and a lower electrode 138 is formed so as to be in contact with a part of the exposed surface of the base layer 131.

  In the light receiving unit 130, the upper multilayer mirror 135 is p-type, and the light-receiving layer 133 is i-type not doped with impurities (i-type is intrinsic, that is, has intrinsic carriers inherent in a semiconductor). In addition, since the lower multilayer film reflecting mirror 132 is n-type, the light receiving unit 130 can function as a pin photodiode.

  As illustrated in FIG. 2B, the light receiving unit 130 includes an impurity diffusion region 139 in which a contact layer 136 and a part of the upper multilayer film reflecting mirror 135 are doped with high-concentration impurities. The upper multilayer mirror 135 has a multilayer structure made of materials having different refractive indexes. In the upper multilayer mirror 135, impurities represented by zinc (Zn) are diffused at a high concentration. A part of the upper multilayer reflector 135 is disordered, and a region (impurity diffusion region 139) having a substantially uniform composition is formed. When a part of the upper multilayer reflector 135 is disordered, the material becomes substantially transparent at the wavelength of the received light 103, and the light receiving unit 130 can receive the received light 103 efficiently by the light receiving layer 133. As a method for diffusing impurities, thermal diffusion or ion implantation can be used. Before the impurity was diffused, the upper multilayer reflector 135 had a high refractive index layer and a low refractive index layer (FIG. 3 (a)). The rate layer becomes mixed crystal, and the interface between them becomes unclear (FIG. 3C). Therefore, in the conventional configuration in which impurities are not diffused in the upper multilayer reflector 135, the upper multilayer reflector 135 has a reflectance of 99% or more at the emission wavelength λ of the light emitting unit 120 (FIG. 3 ( b)) confirmed that the reflectivity was reduced to less than half by the diffusion of impurities (FIG. 3D).

  In FIG. 1A, the number of layers of the upper multilayer reflector 135 of the light receiving unit 130 is equal to the number of layers of the upper multilayer reflector 125 of the light emitting unit 120. The number of layers of the reflecting mirror 135 may be less than the number of layers of the upper multilayer reflecting mirror 125 of the light emitting unit 120, or a structure without the upper multilayer reflecting mirror 135 may be employed.

  In FIG. 1, the surface of each layer constituting the light receiving unit 130 is formed flat, but unevenness is formed on the surface of the light receiving layer 133, the current confinement layer 134, the upper multilayer reflector 135, or the contact layer 136. May be.

  In FIG. 1, the upper electrode 127 and the lower electrode 128 of the light emitting unit 120 and the upper electrode 137 and the lower electrode 138 of the light receiving unit 130 are independent, but for example, the lower electrode 128 of the light emitting unit 120 and the upper part of the light receiving unit 130 A structure in which the electrode 137 is at a common potential may be used.

In FIG. 1, the substrate side is n-type and the surface side is p-type, but the substrate side may be p-type and the surface side may be n-type.
(Second Embodiment)
An optical transceiver 201 according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 4A shows a cross-sectional configuration of the optical transceiver 201 according to the second embodiment. The light emitting unit 220 transmits the transmission light 102 and the light receiving unit 230 receives the reception light 103. Yes. FIG. 4B shows a surface configuration of the optical transceiver 201 according to the first embodiment.

  The optical transceiver 201 of this embodiment includes a light emitting unit 220 and a light receiving unit 230 formed on the substrate 10 as shown in FIG. The light emitting unit 220 and the light receiving unit 230 include independent electrodes, and can be driven independently.

  Next, the structure, manufacturing method, and operation principle of the optical transceiver 201 according to the present embodiment will be described in detail with reference to FIGS. The optical transceiver 201 according to the second embodiment includes a light emitting unit 220 and a light receiving unit 230 on the substrate 10. The light emitting unit 220 includes a base layer 121, a lower multilayer reflector 122, a light emitting layer 123, a current confinement layer 124, an upper multilayer reflector 1125, a contact layer 126, an upper electrode 127 and a lower electrode 128. Have. As a structure constituting the light receiving unit 230, the base layer 131, the lower multilayer reflector 132, the light receiving layer 133, the current confinement layer 134, the upper multilayer reflector 135, the contact layer 136, the upper electrode 137, the lower electrode 138, and impurity diffusion A region 139 is included.

Next, a structure formed by crystal growth will be described with reference to FIG. The substrate 10 is made of semi-insulating gallium arsenide (GaAs). The underlayer 21 is formed by crystal growth of n-type GaAs on the substrate 10. The lower multilayer mirror 22 is a multilayer film in which n-type Al _0.12 Ga _0.88 As layers and n-type Al _0.90 Ga _0.10 As layers are alternately stacked. The lower multilayer mirror 22 is doped with silicon as an n-type impurity. The thickness of each layer is λ / 4n (λ is the laser oscillation wavelength of the light emitting unit 220, and n is the refractive index of the medium), and 34.5 periods are stacked.

Active layer 23, the well layer made of undoped GaAs _layer, a barrier layer made of Al _{0.30 Ga 0.70} As _layer, the lower spacer layer and the upper spacer layer made of Al _{0.30 Ga 0.70} As layer is laminated The quantum well structure is used, and the number of well layers is three periods. The film thickness of the active layer 23 is λ / n.

The current confinement layer 24 includes a p-type Al _0.98 Ga _0.02 As layer, and is configured to replace a part of the p-type Al _0.90 Ga _0.10 As layer in the upper multilayer reflector 25. Has been.

The upper multilayer film reflector 25 is a multilayer film in which p-type Al _0.12 Ga _0.88 As layers and p-type Al _0.90 Ga _0.10 As layers are alternately stacked. The upper multilayer mirror 25 is doped with carbon as a p-type impurity. The thickness of each layer is λ / 4n, and 9.5 periods are stacked.

The contact layer 26 is made of a p-type GaAs layer. In order to reduce the contact resistance with the electrode, the contact layer 26 is doped with carbon, which is a p-type impurity, at a high concentration of 1 × 10 ¹⁹ cm ⁻³ or more.

The light emitting unit 220 includes a contact layer 126, an upper multilayer reflector 125, a current confinement layer 124, a light emitting layer 123, a lower multilayer reflector 122, and a part of the base layer 121 constituting the light emitter 220, as a base layer 121. Are separated from the periphery by a recess formed by selectively removing a part of the substrate 10 to be exposed and a recess formed by selectively removing a part of the substrate 10 to be exposed (FIG. 5 (d)), and has a cylindrical structure with a diameter of about 20 μm. An upper electrode 127 is formed so as to be in contact with part of the surface of the contact layer 126, and a lower electrode 128 is formed so as to be in contact with part of the exposed surface of the base layer 121. As shown in FIGS. 4A and 5C, a first microstructure 140 is formed at the center of the contact layer 126 surface. The first microstructure 140 includes an intermediate layer 141, a minute metal array 142, and a cap layer 143. In the present embodiment, the minute metallic array 142 is disposed in the opening is rectangular lattice shape, lattice spacing P ₁ in the short axis direction is 375 nm, the lattice spacing P ₂ in the long axis direction has a 525 nm. The lattice spacing P _{1 in the} minor axis direction satisfies the surface plasmon resonance condition shown in the equation (1).

0.9 × P ₁ ≦ λ × (i ² + j ² ) ^1/2 / (ε ₁ ε ₂ / (ε ₁ + ε ₂ )) ^1/2 ≦ 1.1 × P ₁
..Formula (1)
Where λ is the wavelength of the laser light, i and j are non-negative integers (0, 1, 2,...), Ε ₁ is the dielectric constant of the micro metal array 142, and ε ₂ is the upper surface of the micro metal array 142 or This is the dielectric constant of the medium in contact with the lower surface.

In the present embodiment, the emission wavelength λ of the laser light is 850 nm, the dielectric constant ε ₁ of the micro metal array 142 made of Ag is −32, and the micro metal array 142 is in contact with SiN of the cap layer 143. The dielectric constant ε ₂ of the surrounding medium is 4. Furthermore, if (i ² + j ² ) = 1, the range of the lattice spacing P of the aperture satisfying the surface plasmon resonance condition is 355 nm to 435 nm from the equation (1). Therefore, the lattice spacing of the openings in this embodiment satisfies the surface plasmon resonance condition. We have experimentally found that the surface plasmon resonance effect of Ag as the material of the micro metal array 142 and the material SiN of the cap layer 143 is stronger than the resonance between Ag and SiO ₂ , The linearly polarized light can be transmitted through the minute metal array 142 more strongly.

  Thus, by arranging the openings in the micro metal array 142 so as to satisfy the surface plasmon resonance condition, light of 850 nm oscillated in the resonator is efficiently converted into surface plasmons on the surface of the micro metal array 142. The converted surface plasmon is converted again into light on the cap layer 143 side of the micro metal array 142 and emitted outside the resonator.

In the light receiving unit 230, the contact layer 136, the upper multilayer reflector 135, the current confinement layer 134, the light receiving layer 133, the lower multilayer reflector 132, and a part of the base layer 131 are partly disposed near the light emitting unit 220. It is separated from the periphery by a recess formed by selectively removing it until it is exposed, and a recess formed by selectively removing a part of the substrate 10 until it is exposed (FIG. 5). (D)). An upper electrode 137 is formed so as to be in contact with a part of the contact layer 136, and a lower electrode 138 is formed so as to be in contact with a part of the exposed surface of the base layer 131. At the center of the surface of the contact layer 136, a second microstructure 150 is formed as shown in FIGS. 4 (a) and 5 (c). In the present embodiment, the minute metal array 152 is provided with a opening Nagakata lattice pattern, the lattice spacing P ₁ in the short axis direction is 375 nm, the lattice spacing P ₂ in the long axis direction has a 525 nm. Lattice spacing P ₁ in the short-axis direction satisfies the surface plasmon resonance condition of Formula (1).

0.9 × P ₁ ≦ λ × (i ² + j ² ) ^1/2 / (ε ₁ ε ₂ / (ε ₁ + ε ₂ )) ^1/2 ≦ 1.1 × P ₁
..Formula (1)
Here, λ is the wavelength of the laser beam, i and j are non-negative integers (0, 1, 2,...), Ε ₁ is the dielectric constant of the micro metal array 152, and ε ₂ is the upper surface of the micro metal array 152 or This is the dielectric constant of the medium in contact with the lower surface.

In the present embodiment, the emission wavelength λ of the laser beam is 850 nm, the dielectric constant ε ₁ of the micro metal array 152 made of Ag is −32, and the micro metal array 152 is in contact with SiN of the cap layer 143. The dielectric constant ε ₂ of the surrounding medium is 4. Furthermore, if (i ² + j ² ) = 1, the range of the lattice spacing P of the aperture satisfying the surface plasmon resonance condition is 355 nm to 435 nm from the equation (1). Therefore, the lattice spacing of the openings in this embodiment satisfies the surface plasmon resonance condition. We have experimentally found that the surface plasmon resonance effect between Ag, which is the material of the micro metal array 142, and SiN, which is the material of the cap layer 143, is stronger than the resonance between Ag and SiO ₂ . Linearly polarized light is stronger and can be transmitted through the minute metal array 152.

  Thus, by arranging the openings in the micro metal array 152 so as to satisfy the surface plasmon resonance condition, light of 850 nm oscillated in the resonator is efficiently converted into surface plasmons on the surface of the micro metal array 152. The converted surface plasmon is converted again into light on the cap layer 143 side of the micro metal array 152 and emitted outside the resonator.

  In the light emitting unit 220, the upper multilayer reflector 135 is p-type, the light receiving layer 133 is i-type without doping impurities, and the lower multilayer reflector 132 is n-type. It is possible to function as.

  In FIG. 5A, the number of layers of the upper multilayer reflector 135 of the light receiving unit 230 is equal to the number of layers of the upper multilayer reflector 125 of the light emitting unit 220. The number of layers of the reflecting mirror 135 may be smaller than the number of layers of the upper multilayer reflecting mirror 125 of the light emitting unit 220, or a structure without the upper multilayer reflecting mirror 135 may be employed.

  In FIG. 5, the surface of each layer constituting the light receiving unit 230 is formed flat, but unevenness is formed on the surface of the light receiving layer 133, the current confinement layer 134, the upper multilayer reflector 135, or the contact layer 136. May be.

  In FIG. 5, the upper electrode 127 and the lower electrode 128 of the light emitting unit 220 and the upper electrode 137 and the lower electrode 138 of the light receiving unit 230 are independent, but for example, the lower electrode 128 of the light emitting unit 220 and the upper part of the light receiving unit 230 A structure in which the electrode 137 is at a common potential may be used.

  In FIG. 5, the substrate side is n-type and the surface side is p-type, but the substrate side may be p-type and the surface side may be n-type.

  In the first microstructure 140, circular openings are formed in a lattice shape. However, the first microstructure 140 is not limited to the openings, and may be uneven. The shape of the unevenness is any dimension as long as it is shorter than the wavelength of the emitted light. It may be in shape. For example, an elliptical shape, a rectangular shape, a square shape, a rhombus shape, or the like may be used. Alternatively, a stripe-shaped one-dimensional periodic structure may be used.

In the second microstructure 150, the circular openings are formed in a lattice shape. However, the second microstructure 150 is not limited to the openings, and may be uneven. The shape of the unevenness may be any dimension as long as it is shorter than the wavelength of the emitted light. It may be in shape. For example, an elliptical shape, a rectangular shape, a square shape, a rhombus shape, or the like may be used. Alternatively, a stripe-shaped one-dimensional periodic structure may be used. Further, by forming the periodic structure in a shape orthogonal to the unevenness formed in the first microstructure 140, the polarization components of the transmitted light 102 of the light emitting unit 220 and the received light 103 of the light receiving unit 230 can be orthogonalized. It becomes possible.
(Third embodiment)
An optical transceiver 301 according to a third embodiment of the present invention will be described with reference to the drawings.

  FIG. 6 shows a top view of an optical transceiver 301 according to the third embodiment. This embodiment is substantially the same as the configuration of the second embodiment, the difference is the configuration of the first microstructure 340 and the second microstructure 350, and the other is substantially the same, and is different. Only the point will be described.

  The first microstructure 340 is a wire grid in which fine metal wires such as aluminum are arranged at equal intervals in the vertical direction with respect to the drawing, and the second fine structure 350 is a metal fine wire with respect to the drawing. It is a wire grid arranged in the horizontal direction at equal intervals.

With this configuration, light emitted from the first microstructure 340 becomes light having a vertical polarization direction in the drawing. On the other hand, light that can be received by the second microstructure 350 is light having a horizontal polarization direction. As a result, when the light emitted from the first microstructure 340 is reflected by a component other than the predetermined optical component and reaches the second microstructure 350, the light passes through the second microstructure 350 and is received by the light receiving unit 330. Therefore, it is possible to reduce the noise of the transmitted / received signal.
(Fourth embodiment)
An optical transceiver 401 according to a fourth embodiment of the present invention will be described with reference to the drawings.

  FIG. 7 shows a top view of an optical transceiver 401 according to the fourth embodiment. This embodiment has substantially the same configuration as that of the second embodiment, the difference is the configuration of the first microstructure 440 and the second microstructure 450, and the rest is substantially the same, so only the differences will be described. .

  The first microstructure 440 is a hole array in which minute aperture holes are arranged at a predetermined interval in a metal film such as Ag in the longitudinal direction with respect to the drawing. Similarly, the second microstructure 450 is also Ag or the like. This is a hole array in which minute opening holes are arranged at predetermined intervals in the metal film.

With this configuration, light emitted from the first microstructure 440 becomes light having a vertical polarization direction in the drawing. On the other hand, light that can be received by the second microstructure 450 is light having a horizontal polarization direction. Thereby, when the light emitted from the first microstructure 440 is reflected by other than the predetermined optical component and reaches the second microstructure 450, the light passes through the second microstructure 450 and is received by the light receiving unit. Since no light is received at 430, it is possible to reduce the noise of the transmitted and received signals.
(Fifth embodiment)
An optical transmission / reception system 500 according to a fifth embodiment of the present invention will be described with reference to the drawings.

  FIG. 8 is a schematic perspective view of an optical transmission / reception system 500 according to the fifth embodiment. The present embodiment is an optical transmission / reception system using two optical transmission / reception apparatuses of the third embodiment. The optical transmission / reception system 500 includes two optical transmission / reception devices 501, an optical transmission / reception device 551, and two collimating lenses 590 and 591 arranged at facing positions. The optical transmitter / receiver 501 and the collimator lens 590 are fixed at positions separated from each other by a predetermined distance, and the collimator lens 590 converts the light 520 emitted from the transmitter 510 of the optical transmitter / receiver 501 into parallel light. The same applies to the optical transmitter / receiver 551 and the collimator lens 591. The collimator lens 591 converts the light 570 emitted from the transmitter 560 into parallel light. At this time, the light emitted from the transmission unit 510 of the optical transmission / reception device 501 is horizontally polarized light, and the reception unit 511 receives only polarized light in the vertical direction. On the other hand, light emitted from the transmission unit 560 of the optical transmission / reception device 551 is vertically polarized light, and the reception unit 561 receives only polarized light in the horizontal direction. The distance between the collimating lenses 590 and 591 can be any distance.

  The horizontally polarized light 520a emitted from the transmission unit 510 of the optical transmission / reception device 501 is converted into parallel light 520b by the collimator lens 590 and propagates in the space. The parallel light 520b received by the collimator lens 591 becomes condensed light 520c and is received by the receiving unit 561 of the optical transmission / reception device 551. On the other hand, the vertically polarized light 570a emitted from the transmission unit 560 of the optical transmission / reception device 551 becomes parallel light 570b by the collimator lens 591 and propagates in the space. The parallel light 570 b received by the collimator lens 590 becomes the condensed light 570 c and is received by the receiving unit 511 of the optical transmission / reception device 501. At this time, for example, even if a part of the polarized light 570a emitted from the transmission unit 560 is reflected by the surface of the collimator lens 591 and enters the reception unit 561 (light 585 shown in FIG. 8), the reception unit 561 remains in the horizontal direction. Since it can receive only the polarized light, it does not become noise.

With the above configuration, it can be seen that low noise can be realized in an optical transmission / reception system using an optical transmission / reception apparatus.
(Sixth embodiment)
An optical transmission / reception system 600 according to a sixth embodiment of the present invention will be described with reference to the drawings.

  FIG. 9 is a perspective view of the vicinity of the optical transmission / reception apparatus of the optical transmission / reception system according to the sixth embodiment. This embodiment is different from the optical transmission / reception system 500 of the fifth embodiment only in the configuration of the optical transmission / reception apparatus, and only that portion will be described.

  FIG. 9A shows a combination of the optical transceiver 651 and the polarization diffraction grating element 695, which can be replaced with the optical transceiver 551 of the fifth embodiment shown in FIG. FIG. 9B shows a combination of the optical transmission / reception device 601 and the polarization diffraction grating element 696, which can be replaced with the optical transmission / reception device 501 of the fifth embodiment shown in FIG. Polarization diffraction grating elements 695 and 696 are optical elements each having a polarization diffraction grating formed on the surface, and function as a diffraction grating for polarized light in a specific direction, but polarized light in a direction perpendicular to the polarized light. Has a feature that does not function as a diffraction grating.

  Specifically, in FIG. 9A, the outgoing light 670 having the polarization 671 in the vertical direction emitted from the transmission unit 660 of the optical transceiver 651 passes through the polarization grating element 695 and travels to a collimator lens (not shown). However, at this time, the outgoing light 670 is not diffracted by the polarization diffraction grating element 695. On the other hand, incident light 620 that enters the polarization diffraction grating element 695 from a collimator lens (not shown) is diffracted by the polarization diffraction grating element 695 and enters the reception unit 661.

  On the other hand, in FIG. 9B, in the optical transmission / reception apparatus 601 as well, outgoing light 630 having vertically polarized light 631 emitted from the transmission unit 610 passes through the polarization grating element 696 and travels to a collimating lens (not shown). However, at this time, the outgoing light 630 is not diffracted by the polarization diffraction grating element 696. On the other hand, incident light 680 incident on the polarization diffraction grating element 696 from a collimator lens (not shown) is diffracted by the polarization diffraction grating element 696 and is incident on the reception unit 611.

With the configuration as described above, it is possible to make the optical axes of the outgoing light and the incident light from the polarization diffraction grating of the optical transmission / reception system the same, so it is possible to construct the optical transmission / reception system more easily.
(Seventh embodiment)
An optical pickup system 700 according to a seventh embodiment of the present invention will be described with reference to the drawings.

  FIG. 10 shows a schematic configuration diagram of an optical pickup system according to the seventh embodiment. The present embodiment is an optical pickup system using the optical transceiver of the third embodiment. The optical pickup system 700 irradiates the optical disc 702 with the transmission light 102 output from the light emitting unit 220 formed in the optical transmission / reception device 701 via the objective lens 703 and the diffraction grating 704, and receives the received light 103 reflected. It is configured to read by the unit 230.

  With the above configuration, it can be seen that low noise and small size of the system can be realized in the optical pickup system using the optical transceiver.

  The optical transmission / reception apparatus and optical transmission / reception system according to the present invention are useful as an optical communication transmission / reception apparatus that requires low-cost and highly reliable operation.

It is a figure which shows the structure of the optical transmission / reception apparatus which concerns on 1st Embodiment. It is a figure which shows the manufacturing method of the optical transmission / reception apparatus which concerns on 1st Embodiment. In the optical transceiver according to the first embodiment, changes in the refractive index and the reflectance before and after forming the impurity diffusion region in the upper multilayer reflector of the light receiving portion are shown. It is a figure which shows the structure of the optical transmission / reception apparatus which concerns on 2nd Embodiment. It is a figure which shows the manufacturing method of the optical transmission / reception apparatus which concerns on 2nd Embodiment. It is a figure which shows the structure of the optical transmission / reception apparatus which concerns on 3rd Embodiment. It is a figure which shows the structure of the optical transmission / reception apparatus which concerns on 4th Embodiment. It is a figure which shows the structure of the optical transmission / reception system which concerns on 5th Embodiment. It is a figure which shows the structure of the optical transmission / reception system which concerns on 6th Embodiment. It is a figure which shows the structure of the optical pick-up system which concerns on 7th Embodiment. It is a figure which shows the structure of the optical transmitter / receiver in a prior art example.

Explanation of symbols

10 Substrate (semiconductor substrate)
101, 201, 301, 401 Optical transceiver
120,220 Light emitting part
21, 121, 131 Underlayer
22, 122, 132 Lower multilayer reflector (first reflector or second reflector)
23,123 Light emitting layer (active layer)
24, 124, 134 Current confinement layer
124a, 134a Current confinement region
124b, 134b oxide high resistance region
25, 125, 135 Upper multilayer reflector (second reflector or first reflector)
26, 126, 136 Contact layer
127,137 Upper electrode
128,138 Lower electrode
130, 230, 330, 430
133 Light-receiving layer
139 Impurity diffusion region
140, 340, 440 First microstructure
150, 350, 450 Second microstructure
141,151 intermediate layer
142,152 Micro metal array
143,153 Cap layer
500,600 Optical transmission / reception system
501, 551, 601, 651 Optical transceiver
510, 560, 610, 660 transmitter
511, 561, 611, 661 receiver
590,591 Collimating lens
695,696 Polarization diffraction grating element
700 Optical pickup system
701 Optical transceiver
702 Optical disc
703 Objective lens
704 diffraction grating

Claims (9)

A semiconductor substrate;
At least one light emitting part formed on the semiconductor substrate;
And at least one light receiving portion formed on the semiconductor substrate,
Each of the light emitting unit and the light receiving unit includes a first reflecting mirror, an active layer, and a second reflecting mirror,
The first reflecting mirror is disposed between the substrate and the active layer in each of the light emitting unit and the light receiving unit,
The active layer is disposed between the first reflecting mirror and the second reflecting mirror in each of the light emitting unit and the light receiving unit,
An optical transmission / reception apparatus, wherein a part of the second reflecting mirror of the light receiving unit is provided with a region where impurities are diffused.   2. The optical transceiver according to claim 1, wherein each of the first reflecting mirror and the second reflecting mirror is a semiconductor multilayer film.   The optical transmitter / receiver according to claim 1, wherein a step between the surface of the light emitting unit and the surface of the light receiving unit is equal to or less than a wavelength of light emitted by the light emitting unit.   4. The microstructure according to claim 1, wherein at least one of the light emitting part and the light receiving part is formed with a microstructure formed so that an interval is equal to or less than an emission wavelength of the light emitting part. The optical transmission / reception apparatus according to one.   The optical transceiver according to claim 4, wherein the microstructure has a periodic structure.   6. The optical transmission / reception apparatus according to claim 4, wherein the microstructure is made of metal.   The optical transceiver according to any one of claims 4 to 6, wherein the microstructure is formed on at least one surface of the light emitting unit and the light receiving unit. The semiconductor multilayer film is made of Al _1-x Ga _x As,
The optical transmission / reception apparatus according to claim 1, wherein the impurity is Zn.   An optical transmission / reception system, wherein a plurality of optical signals having different linear polarization directions are transmitted using the optical transmission / reception apparatus according to claim 1.

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