JP4671672B2 - Light receiving / emitting device, optical transmission / reception module, optical transmission module, and optical communication system - Google Patents

Description

The present invention, light emitting and receiving device, an optical transceiver module, an optical transmission module Contact and optical communication systems.

  In recent years, optical transmission technology has been developed not only in trunk transmission networks but also in LANs, optical access systems, and home networks. In an optical access system such as FTTH (Fiber-To-The-Home), an optical integrated transmission / reception module in which an optical transmitter, an optical receiver, and a light receiving element for monitoring the optical output of an LD are integrated in a hybrid has been developed. Yes. However, the module size is several centimeters, and further downsizing of the module is demanded. In addition, in the optical LAN, a transmission capacity of 10 Gbps is realized, but further increase in the transmission capacity is demanded in the future, and methods such as parallel optical transmission and wavelength division multiplexing optical transmission have been studied. Yes. In parallel optical transmission and wavelength division multiplexing optical transmission, since the number of light sources and light receiving elements increases, downsizing of the module size is a serious issue. As one method for reducing the module size, an element in which a light source and a light receiving element are monolithically integrated has been studied.

  In recent years, vertical cavity surface emitting lasers (VCSELs) have come to be used as light sources for LAN and optical interconnection. The VCSEL has lower power consumption than conventional edge-emitting semiconductor lasers, requires no cleaving in the manufacturing process, and can inspect elements in the wafer state. Have. Therefore, the VCSEL is suitable for a transmission method using a plurality of light sources such as parallel optical transmission and wavelength division multiplexing optical transmission.

  For example, Patent Literature 1, Patent Literature 2, and Patent Literature 3 show a module in which a VCSEL light source and a light receiving element are monolithically integrated.

  That is, in the module of Patent Document 1, the VCSEL structure light emitting portion and the light receiving portion are integrated on the same substrate, the light emitting portion has a single resonator structure, and the light receiving portion has a double resonator structure. In the light receiving section, two resonators that resonate at the same wavelength are connected via an appropriate barrier, and the absorption spectrum is designed to be nearly flat. As a result, the light receiving band can be widened.

  In the module disclosed in Patent Document 2, a region where the first PIN photodiode and the VCSEL are integrated and a region where the second PIN photodiode is formed are monolithically integrated on the high-resistance semiconductor substrate. The first PIN type photodiode detects the emission light of the VCSEL, and the second PIN type photodiode detects the light reflected from the VCSEL or light from other light emitting elements. In addition, the second PIN photodiode has a resonator structure and improves the light receiving sensitivity.

In the module of Patent Document 3, a photodiode region and a VCSEL region are monolithically integrated on a high-resistance semiconductor substrate, and the photodiode region includes a plurality of pin-type photodiodes having light absorption layers with different bandwidths. It is possible to individually detect light of different wavelengths. In addition, the monolithic light receiving element stacked under the VCSEL can monitor the amount of light of the VCSEL and perform APC (auto power control) of the VCSEL.
Japanese Patent Application Laid-Open No. 5-29989 JP-A-10-242500 JP-A-11-330532

  In Patent Document 1, Patent Document 2, and Patent Document 3, which are the conventional technologies described above, the VCSEL and the light receiving unit, which are light emitting units, are monolithically integrated on the same substrate, and a compact optical transceiver module can be configured. ing. However, the light-emitting part and the light-receiving part have different stacking configurations. This is because, conventionally, a configuration suitable for a VCSEL which is a light emitting portion is different from a configuration suitable for a light receiving element, and thus it is difficult to form a highly sensitive light receiving element without degrading the characteristics of the VCSEL with the same structure. Because it was.

  As described above, in the above-described prior art, since the laminated structure is different between the light emitting portion and the light receiving portion, it is necessary to remove a part of the laminated structure by etching, or to perform regrowth after etching, and the manufacturing process is complicated. Met. In the light receiving element having a VCSEL or a resonator structure, the resonance wavelength is very sensitive to the layer thickness, and it is difficult to strictly control the layer thickness in the etching process.

The present invention aims at solving the above problems, to provide a light emitting and receiving equipment which are integrated readily manufacturable monolithic.

Further, by using the light emitting and receiving equipment, small, low-cost optical transceiver module, and its object is to provide an optical transmission module Contact and optical communication systems.

In order to achieve the above object, the invention described in claim 1 is characterized in that on a substrate, a first semiconductor multilayer reflector, a first resonator, a second semiconductor multilayer reflector, a second resonator, A third semiconductor multilayer mirror is provided, wherein one of the first resonator and the second resonator is provided with an active layer , and the other resonator is provided with a light absorption layer. A surface-type light emitting element having a resonator length different from that of the first resonator and the second resonator, having a different resonance wavelength, and provided with an electrode capable of applying a voltage to the active layer; A surface light-receiving element having a laminated structure identical to that of the surface light-emitting element and provided with an electrode capable of applying a voltage to the light absorption layer is monolithically integrated on the substrate. The light emitting / receiving device.

Further, a second aspect of the present invention, by using a light receiving and emitting device according to claim 1 Symbol mounting an optical transceiver module, characterized that it is capable of optical bidirectional transmission and reception.

According to a third aspect of the present invention, in the light emitting / receiving device according to the first aspect, the light absorption layer is made of a material that absorbs light generated in the active layer. It is.

According to a fourth aspect of the present invention, there is provided the light emitting / receiving device according to the third aspect and the electric light output from the light absorption layer of the light emitting / receiving device so that the light intensity output from the light emitting / receiving device is constant. An optical transmission module comprising current control means for controlling a current injected into an active layer of the light emitting / receiving device according to a signal.

According to a fifth aspect of the present invention, in the light emitting / receiving device according to the first or third aspect , the active layer and / or the light absorption layer is composed of a mixed crystal semiconductor containing nitrogen and another group V element. It is characterized by being.

The invention of claim 6, wherein the optical transceiver module according to claim 2, or a communication system, characterized by being used an optical transmission module according to claim 4, wherein.

According to the first aspect of the present invention, the first semiconductor multilayer film reflecting mirror, the first resonator, the second semiconductor multilayer film reflecting mirror, the second resonator, and the third semiconductor multilayer film are formed on the substrate. A reflection mirror, and one of the first resonator and the second resonator is provided with an active layer, and the other resonator is provided with a light absorption layer; A surface-emitting device having a resonator length different from that of the second resonator and having a different resonance wavelength and provided with an electrode capable of applying a voltage to the active layer; and consists surface light-emitting device the same lamination and structure, and the light absorption layer can electrode surface light-receiving element provided applying a voltage to is being monolithically integrated, in the invention of claim 1, the The first resonator and the second resonator are optically coupled to form two resonance wavelengths λ 1 and λ 2. Since the resonator length of the resonator is different from that of the second resonator, light having a long resonance wavelength is mainly confined in the resonator having a long resonator length. In addition, light having a short resonance wavelength is mainly confined in a resonator having a short resonator length. In the surface light emitting device, the light (λ1) generated in the active layer can be confined in one resonator and the light confinement factor can be kept high, so that the surface light emitting device can be operated with a low threshold current. . In addition, in the surface light receiving element, when light having the wavelength λ2 is incident from the outside, the light having the wavelength λ2 is confined in the other resonator and is resonantly absorbed by the light absorption layer. Can be formed. Accordingly, since the surface light emitting element and the surface light receiving element monolithically integrated on the same substrate can be formed with the same laminated structure, it is possible to provide a light emitting and receiving device that can be easily manufactured.

Further, a second aspect of the present invention, by using a light receiving and emitting device according to claim 1 Symbol mounting a optical transceiver module, characterized that it is capable of optical bidirectional transmission and reception, placing claim 1 Symbol The light emitting / receiving device has a monolithically integrated surface light emitting unit or surface light emitting element that operates at a low threshold and a highly sensitive surface light receiving unit or surface light receiving element, and further includes a surface light emitting unit or surface light emitting unit. Since the element and the surface light receiving section or the surface light receiving element have the same structure, they can be easily manufactured. Therefore, the optical transceiver module can be reduced in size and cost.

According to a third aspect of the present invention, in the light emitting / receiving device according to the first aspect, the light absorption layer is made of a material that absorbs light generated in the active layer, and the light absorption layer is active. Since the light generated in the layer is absorbed, the laser light quantity of the surface light emitting unit can be monitored by the light absorption layer. At this time, since the resonator lengths of the first resonator and the second resonator are different, the ratio of light coupled to the active layer can be increased, and the ratio of light coupled to the light absorption layer can be reduced. The low threshold current operation of the surface light emitting unit can be satisfied at the same time while obtaining the necessary light intensity monitor signal.

According to a fourth aspect of the present invention, there is provided the light emitting / receiving device according to the third aspect and the electric light output from the light absorption layer of the light emitting / receiving device so that the light intensity output from the light emitting / receiving device is constant. 4. An optical transmission module comprising: current control means for controlling a current injected into an active layer of the light emitting / receiving device according to a signal; and the light emitting / receiving device according to claim 3 and the light emitting / receiving device. Current control means for controlling the current injected into the active layer of the light emitting / receiving device by an electric signal output from the light absorbing layer of the light emitting / receiving device so that the light intensity output from the light receiving device is constant. Therefore, even when an environmental temperature change or an element change with time occurs, a constant laser light signal can be output from the optical transmission module. In addition, since the surface light emitting unit and the monitor surface light receiving unit are monolithically integrated, the number of components is small, and the mounting cost can be reduced.

According to a fifth aspect of the present invention, in the light emitting / receiving device according to the first or third aspect , the active layer and / or the light absorption layer is composed of a mixed crystal semiconductor containing nitrogen and another group V element. Therefore, an active layer and / or a light absorption layer having a long wavelength band suitable for transmission of a quartz optical fiber can be formed on a GaAs substrate. Therefore, a GaAs / AlGaAs DBR having high reflectivity and excellent thermal conductivity can be used, and a high-performance light receiving and emitting device can be formed.

  Further, in the present invention, optical communication is performed using light of two different wavelengths, but the vicinity of 1.31 μm where the dispersion of the quartz optical fiber is zero can be used, and the signal degradation due to the wavelength dispersion after the transmission of the quartz optical fiber. Can be suppressed.

Further, an invention according to claim 6, wherein the optical transceiver module of claim 2 or a communication system, characterized by being used an optical transmission module according to claim 4, claim 2, wherein the optical transceiver module, or by an optical transmission module according to claim 4 wherein is used to simplify the manufacturing process, size reduction of the module size, it is possible to decrease the number of parts. Thereby, a low-cost optical communication system can be realized.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

(First form)
In the first embodiment of the present invention, a first semiconductor multilayer reflector, a first resonator, a second semiconductor multilayer reflector, a second resonator, and a third semiconductor multilayer reflector are formed on a substrate. A mirror, and an active layer is provided in one of the first resonator and the second resonator to form a surface light-emitting portion, and a light absorption layer is provided in the other resonator. A resonator that is different from the first resonator and the second resonator is provided with a surface-type light-receiving portion and provided with electrodes capable of independently applying a voltage to the active layer and the light absorption layer. A light receiving and emitting device characterized by having a length.

  In the first embodiment of the present invention, the first semiconductor multilayer film reflector, the first resonator, the second semiconductor multilayer film reflector, the second resonator, and the third semiconductor multilayer film reflector are formed on the substrate. A mirror, and an active layer is provided in one of the first resonator and the second resonator to form a surface light-emitting portion, and a light absorption layer is provided in the other resonator. A resonator that is different from the first resonator and the second resonator is provided with a surface-type light-receiving portion and provided with electrodes capable of independently applying a voltage to the active layer and the light absorption layer. The first resonator and the second resonator are optically coupled to form two resonance wavelengths λ1 and λ2, but the first resonator and the second resonance Since the resonator lengths of the resonators are different, light having a long resonance wavelength is mainly confined in the resonator having a long resonator length. In addition, light having a short resonance wavelength is mainly confined in a resonator having a short resonator length. Therefore, light (λ1) generated in the active layer can be confined in one resonator and the optical confinement factor can be kept high, so that the surface light emitting unit can be operated with a low threshold current. Further, when light having a wavelength λ2 is incident from the outside, the light having a wavelength λ2 is confined in the other resonator and is resonantly absorbed by the light absorption layer, so that a highly sensitive surface-type light receiving portion can be formed. As a result, it is possible to easily manufacture a light emitting / receiving device (surface type light emitting / receiving integrated element) in which a surface light emitting unit operating at a low threshold and a highly sensitive surface light receiving unit are integrated and integrated.

(Second form)
In the second embodiment of the present invention, the first semiconductor multilayer film reflector, the first resonator, the second semiconductor multilayer film reflector, the second resonator, and the third semiconductor multilayer film reflector are formed on the substrate. The first resonator and the second resonator are each provided with an active layer, and the other resonator is provided with a light absorption layer. And a surface-type light emitting device having a resonator length different from that of the second resonator and provided with an electrode capable of applying a voltage to the active layer;
On the substrate, a surface light-receiving element that has the same laminated structure as the surface light-emitting element and is provided with an electrode capable of applying a voltage to the light absorption layer,
A light emitting and receiving device characterized by being monolithically integrated.

In the second embodiment of the present invention, the first semiconductor multilayer film reflector, the first resonator, the second semiconductor multilayer film reflector, the second resonator, and the third semiconductor multilayer film reflector are formed on the substrate. The first resonator and the second resonator are each provided with an active layer, and the other resonator is provided with a light absorption layer. And a surface-type light emitting device having a resonator length different from that of the second resonator and provided with an electrode capable of applying a voltage to the active layer;
On the substrate, a surface light-receiving element that has the same laminated structure as the surface light-emitting element and is provided with an electrode capable of applying a voltage to the light absorption layer,
In the second embodiment, the first resonator and the second resonator are optically coupled to form two resonance wavelengths λ1 and λ2. Since the resonator lengths of the resonator and the second resonator are different, light having a long resonance wavelength is mainly confined in the resonator having a long resonator length. In addition, light having a short resonance wavelength is mainly confined in a resonator having a short resonator length. In the surface light emitting device, the light (λ1) generated in the active layer can be confined in one resonator and the light confinement factor can be kept high, so that the surface light emitting device can be operated with a low threshold current. . In addition, in the surface light receiving element, when light having the wavelength λ2 is incident from the outside, the light having the wavelength λ2 is confined in the other resonator and is resonantly absorbed by the light absorption layer. Can be formed. Accordingly, since the surface light emitting element and the surface light receiving element monolithically integrated on the same substrate can be formed with the same laminated structure, it is possible to provide a light emitting and receiving device that can be easily manufactured.

(Third form)
According to a third aspect of the present invention, there is provided an optical transmission / reception module characterized in that bidirectional optical transmission / reception is possible using the light emitting / receiving device of the first or second aspect.

  According to a third aspect of the present invention, there is provided an optical transceiver module characterized in that bidirectional optical transmission / reception is possible using the light emitting / receiving device of the first or second aspect. The surface light emitting / receiving device according to the second aspect includes a monolithically integrated surface light emitting unit or surface light emitting element that operates at a low threshold and a highly sensitive surface light receiving unit or surface light receiving element. Since the surface light-emitting element and the surface light-receiving part or the surface light-receiving element have the same structure, they can be easily manufactured. Therefore, the optical transceiver module can be reduced in size and cost.

(4th form)
According to a fourth embodiment of the present invention, a first semiconductor multilayer reflector, a first resonator, a second semiconductor multilayer reflector, a second resonator, and a third semiconductor multilayer reflector are formed on a substrate. The first resonator and the second resonator are provided with active mirrors to form a surface light emitting unit, and the other resonator has a light absorption layer. A surface light-receiving unit for monitoring is formed, and electrodes capable of independently applying a voltage to the active layer and the light absorption layer are provided, and the first resonator and the second resonance are provided. A light receiving and emitting device having a resonator length different from that of the resonator, wherein the light absorption layer is made of a material that absorbs light generated in the active layer.

  In the fourth embodiment of the present invention, the first semiconductor multilayer reflector, the first resonator, the second semiconductor multilayer reflector, the second resonator, and the third semiconductor multilayer reflector are formed on the substrate. The first resonator and the second resonator are provided with active mirrors to form a surface light emitting unit, and the other resonator has a light absorption layer. A surface light-receiving unit for monitoring is formed, and electrodes capable of independently applying a voltage to the active layer and the light absorption layer are provided, and the first resonator and the second resonance are provided. The light absorption layer is made of a material that absorbs light generated in the active layer, and the light absorption layer absorbs light generated in the active layer. The amount of laser light from the surface light emitting unit can be monitored by the absorption layer. At this time, since the resonator lengths of the first resonator and the second resonator are different, the ratio of light coupled to the active layer can be increased, and the ratio of light coupled to the light absorption layer can be reduced. The low threshold current operation of the surface light emitting unit can be satisfied at the same time while obtaining the necessary light intensity monitor signal.

(5th form)
According to a fifth aspect of the present invention, there is provided an electric signal output from the light receiving / emitting device of the fourth aspect and the light absorption layer of the light emitting / receiving device so that the light intensity output from the light receiving / emitting device is constant. And a current control means for controlling the current injected into the active layer of the light emitting / receiving device.

  In the fifth aspect of the present invention, the electric signal output from the light-absorbing layer of the light emitting / receiving device so that the light intensity output from the light emitting / receiving device of the fourth aspect is constant. And a current control means for controlling the current injected into the active layer of the light emitting / receiving device. The light transmitting / receiving device according to the fourth aspect; and Current control means for controlling the current injected into the active layer of the light receiving and emitting device by an electric signal output from the light absorbing layer of the light receiving and emitting device so that the output light intensity is constant. Therefore, even when an environmental temperature change or an element change with time occurs, a constant laser light signal can be output from the optical transmission module. In addition, since the surface light emitting unit and the monitor surface light receiving unit are monolithically integrated, the number of components is small, and the mounting cost can be reduced.

(Sixth form)
According to a sixth aspect of the present invention, in the light emitting / receiving device according to the first, second, or fourth aspect, the active layer and / or the light absorption layer is composed of a mixed crystal semiconductor containing nitrogen and another group V element. It is the light emitting / receiving device characterized by the above.

  According to a sixth aspect of the present invention, in the light emitting / receiving device according to the first, second, or fourth aspect, the active layer and / or the light absorption layer is made of a mixed crystal semiconductor containing nitrogen and another group V element. Therefore, an active layer and / or a light absorption layer having a long wavelength band suitable for transmission of a quartz optical fiber can be formed on a GaAs substrate. Therefore, a GaAs / AlGaAs DBR having high reflectivity and excellent thermal conductivity can be used, and a high-performance light receiving and emitting device can be formed.

  Further, in the present invention, optical communication is performed using light of two different wavelengths, but the vicinity of 1.31 μm where the dispersion of the quartz optical fiber is zero can be used, and the signal degradation due to the wavelength dispersion after the transmission of the quartz optical fiber. Can be suppressed.

(7th form)
According to a seventh aspect of the present invention, a first semiconductor multilayer reflector, a first resonator, a second semiconductor multilayer reflector, a second resonator, and a third semiconductor multilayer reflector are formed on a substrate. The first resonator and the second resonator are each provided with a light absorption layer to form two surface-type light receiving parts, and the first resonator and the second resonator are each provided with a mirror. An electrode capable of applying a voltage independently to the provided light absorption layer is provided, and the first resonator and the second resonator have different resonator lengths. It is a light receiving device.

  In the seventh embodiment of the present invention, the first semiconductor multilayer film reflecting mirror, the first resonator, the second semiconductor multilayer film reflecting mirror, the second resonator, and the third semiconductor multilayer film reflecting are formed on the substrate. The first resonator and the second resonator are each provided with a light absorption layer to form two surface-type light receiving parts, and the first resonator and the second resonator are each provided with a mirror. An electrode capable of applying a voltage independently to the provided light absorption layer is provided, the first resonator and the second resonator have different resonator lengths, and have a wavelength λ1 from the outside. Is incident, the light having the wavelength λ1 is resonated and confined with one of the first resonators, and is resonantly absorbed by the light absorption layer provided in the first resonator. When light having a wavelength λ2 is incident from the outside, the light having a wavelength λ2 is confined in the second resonator and is resonantly absorbed by a light absorption layer provided in the second resonator. As a result, light of two different wavelengths can be selected and received by the same element. In addition, since the first resonator and the second resonator have different resonator lengths, when light is confined in one resonator, the light intensity is reduced by about one to two digits in the other resonator. Therefore, crosstalk between two wavelengths can be reduced.

(8th form)
According to an eighth aspect of the present invention, there is provided an optical receiver module for wavelength division multiplexing optical communication, wherein the optical receiver module uses the light receiving device of the seventh embodiment. It is.

  According to an eighth aspect of the present invention, there is provided an optical receiver module for wavelength division multiplexing optical communication, wherein the optical receiver module uses the light receiving device of the seventh aspect. In this case, the seventh embodiment Since the light receiving device has a wavelength selecting function, it is not necessary to provide an optical branching element, and the optical receiving module can be reduced in size and cost can be reduced.

(9th form)
According to a ninth aspect of the present invention, there is provided a light receiving device according to the seventh embodiment, an electrical signal output from a light absorption layer provided in a first resonator of the light receiving device, and a second resonance of the light receiving device. And a difference calculating means for calculating a difference from an electric signal output from a light absorbing layer provided in the optical device.

  In the ninth embodiment of the present invention, the light receiving device of the seventh embodiment, the electric signal output from the light absorption layer provided in the first resonator of the light receiving device, and the second resonance of the light receiving device. And a difference calculating means for calculating a difference from an electric signal output from a light absorbing layer provided in the optical device, for example, an optical signal corresponding to the wavelength λ1. When the optical signals corresponding to the wavelength λ2 are output at the same time with 0 and 1 inverted, the light of the wavelengths λ1 and λ2 are absorbed by different light absorption layers in the light receiving device according to claim 7. Therefore, the optical signals having wavelengths λ1 and λ2 can be detected separately. By taking the difference between the two signals, it is possible to realize a differential transmission system in which the influence of noise is canceled and reception sensitivity is improved.

(10th form)
A tenth aspect of the present invention is the light receiving apparatus according to the seventh aspect, wherein the light absorption layer is made of a mixed crystal semiconductor containing nitrogen and another group V element.

  In the tenth aspect of the present invention, in the light-receiving device according to the seventh aspect, the light absorption layer is made of a mixed crystal semiconductor containing nitrogen and other group V elements, and is therefore suitable for transmission of quartz optical fibers. A light absorption layer having a long wavelength band can be formed on the GaAs substrate. Therefore, a GaAs / AlGaAs DBR having high reflectivity and excellent thermal conductivity can be used, and a high-performance light receiving device can be formed.

  Further, in the present invention, optical communication is performed using light of two different wavelengths, but the vicinity of 1.31 μm where the dispersion of the quartz optical fiber is zero can be used, and the signal degradation due to the wavelength dispersion after the transmission of the quartz optical fiber. Can be suppressed.

(Eleventh form)
In an eleventh aspect of the present invention, the optical transceiver module according to the third aspect, the optical transmitter module according to the fifth aspect, or the optical receiver module according to the eighth or ninth aspect is used. Is an optical communication system.

  In the eleventh aspect of the present invention, the optical transceiver module according to the third aspect, the optical transmitter module according to the fifth aspect, or the optical receiver module according to the eighth or ninth aspect is used. The module size can be reduced and the number of parts can be reduced. Thereby, a low-cost optical communication system can be realized.

  As described above, the light receiving / emitting device or light receiving device of the present invention includes a first semiconductor multilayer reflector, a first resonator, a second semiconductor multilayer reflector, a second resonator on a substrate. A third semiconductor multilayer mirror is provided, and the first resonator and the second resonator are provided with an active layer or a light absorption layer, and the active layer or light absorption provided in each resonator. The layers operate independently and can have different functions in one stacked structure.

  Further, the first resonator and the second resonator have different resonator lengths. The first resonator and the second resonator are optically coupled to form two resonance wavelengths. The resonator length of the first resonator and the resonator length of the second resonator are They are different and form an asymmetric double resonator structure. In a symmetric double resonator structure, light is almost uniformly confined in the first and second resonators at either of the two resonance wavelengths, but in an asymmetric double resonator structure, a long The light having the resonance wavelength on the wavelength side is strongly confined in the resonator having the longer resonator length, and the light becomes weak in the resonator having the shorter resonator length. Further, the light having the resonance wavelength on the short wavelength side is strongly confined in the resonator having the shorter resonator length, and the light becomes weak in the resonator having the longer resonator length. The invention is characterized by the use of optical confinement asymmetry in two coupled resonators.

  In Example 1 and Example 2 described below, a surface light emitting unit or a surface light emitting element and a surface light receiving unit that receives external light having a wavelength different from the oscillation wavelength of the surface light emitting unit or the surface light emitting element. Alternatively, a surface light receiving element is integrated. In Example 4, the surface light emitting unit and the surface light receiving unit for monitoring the light amount of the surface light emitting unit are integrated. In the sixth embodiment, the surface light-receiving portions that can independently receive two different wavelengths are integrated. In the present invention, since the two resonators are asymmetric, the structure can be optimized independently for each resonator, and high-performance functional areas can be monolithically integrated. Further, it is not necessary to etch or re-grow the laminated structure for each functional region, so that the manufacturing process becomes easy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Example 1 of the present invention corresponds to the first mode. FIG. 1 is a diagram showing a light receiving / emitting device (surface-type light receiving / emitting integrated element) according to a first embodiment of the present invention. Referring to FIG. 1, a first conductive type lower distributed Bragg reflector (DBR) 102, a first spacer layer 103, an active layer 104, and a second spacer are formed on a first conductive type semiconductor single crystal substrate 101. Layer 105, second conductivity type distributed Bragg reflector (DBR) 106, third spacer layer 107, light absorbing layer 108, fourth spacer layer 109, first conductivity type upper distributed Bragg reflector (DBR) 110 Are sequentially stacked.

  A distributed Bragg reflector (DBR) is formed by alternately laminating a high refractive index layer and a low refractive index layer with an optical length that is a quarter of a wavelength. A region sandwiched between the first conductivity type lower DBR 102 and the second conductivity type DBR 106 has a thickness that is an optical length corresponding to one wavelength of the oscillation wavelength, and constitutes a first resonator. The region sandwiched between the second conductivity type DBR 106 and the first conductivity type upper DBR 110 constitutes a second resonator. The first resonator and the second resonator are optically coupled to form two resonance wavelengths. The resonator length of the first resonator and the resonator length of the second resonator are They are different and form an asymmetric double resonator structure.

  Then, the mesa structure is formed by etching from the surface of the stacked structure to the middle of the second conductivity type DBR 106, and the first conductivity type upper DBR 110 has a first surface except for the light emitting portion. An electrode 111 is formed. A second electrode 112 is formed on the bottom surface of the mesa structure. A third electrode 113 is formed on the back surface of the substrate 101.

  In such a structure, by flowing a forward current between the second electrode 112 and the third electrode 113, carriers are injected into the active layer 104 and light is emitted. The light emitted from the active layer 104 resonates at the first resonator and oscillates in the direction perpendicular to the substrate. That is, the active layer 104 is provided in the first resonator to form a surface light emitting unit.

  In addition, by applying a reverse bias between the first electrode 111 and the second electrode 112 via the load resistance, a current flows through the load resistance according to the amount of light absorbed by the light absorption layer 108, The amount of light can be detected. That is, the light absorption layer 108 is provided in the second resonator to form a surface light receiving portion.

Hereinafter, the configuration of the first embodiment will be described using a more specific example. The first-conductivity-type semiconductor single crystal substrate 101 is composed of an n-type GaAs substrate, and the first-conductivity-type lower DBR 102 alternately includes n-type Al _0.2 Ga _0.8 As and n-type AlAs. 30.5 periods are stacked to form an n-type DBR. The first spacer layer 103 is made of Al _0.2 Ga _0.8 As, the active layer 104 is made of a GaAs / Al _0.2 Ga _0.8 As multiple quantum well structure, and the second The spacer layer 105 is made of Al _0.2 Ga _0.8 As. Further, the second conductivity type DBR 106 is formed as a p-type DBR by alternately laminating p-type Al _0.2 Ga _0.8 As and p-type AlAs for 12.5 periods. The third spacer layer 107 is made of Al _0.2 Ga _0.8 As, the light absorption layer 108 is made of Al _0.06 Ga _0.94 As, and the fourth spacer layer 109 is made of The upper DBR 110 of the first conductivity type formed of Al _0.2 Ga _0.8 As is formed as an n-type DBR by alternately stacking n-type Al _0.2 Ga _0.8 As and n-type AlAs for 10 periods. Is formed.

  Note that the active layer 104 and the light absorption layer 108 are configured to be located at the antinodes of the standing wave distribution of light.

  In the first embodiment, the lower DBR 102, the p-type DBR 106, the upper DBR 110, and the first resonator have respective layer thicknesses so as to be phase-matched to a wavelength of 850 nm. The second resonator length was a layer thickness that matched the phase to a wavelength of 800 nm. Thereby, the two resonance wavelengths formed by optically coupling the first resonator and the second resonator are 851 nm and 835 nm.

  As described above, since the resonator lengths of the first resonator and the second resonator are different, light having a wavelength of 851 nm on the long wavelength side is changed to the first resonator having a relatively long resonator length. It is mainly confined (see FIG. 10A). The gain peak wavelength of the active layer 104 is in the vicinity of 850 nm, and the light generated in the active layer 104 when a forward current flows between the second electrode 112 and the third electrode 113 is transmitted from the first resonator. Resonates and oscillates in the direction perpendicular to the substrate 101. At this time, the light intensity in the second resonator is small, and the optical confinement coefficient of the active layer 104 can be kept high. Therefore, the surface light emitting unit can be operated with a low threshold current.

On the other hand, when light having a wavelength of 835 nm is incident from the outside, the light having a wavelength of 835 nm is mainly confined in the second resonator having a relatively short resonator length (see FIG. 10B). That is, the band gap wavelength of the Al _0.06 Ga _0.94 As light absorption layer 108 provided in the second resonator is about 835 nm, and the Al _0.06 Ga _0.94 As light absorption layer 108 is Absorbs light having a wavelength of 835 nm. Therefore, light having a wavelength of 835 nm incident from the outside is resonantly absorbed in the light absorption layer 108 provided in the second resonator. Thereby, a highly sensitive light receiving element can be formed.

Since the Al _0.06 Ga _0.94 As light absorption layer 108 has a band gap wavelength shorter than the oscillation wavelength 851 nm of the surface light emitting unit, the absorption coefficient is small for light with a wavelength of 851 nm. ing. Therefore, even if 851 nm light generated in the active layer 104 is slightly in the second resonator, the internal absorption loss is not increased. Therefore, an increase in threshold current and a decrease in slope efficiency can be suppressed.

  As described above, the device (element) in FIG. 1 is a light emitting / receiving device (surface) in which a surface light emitting unit that emits light having a wavelength of 851 nm and a surface light receiving unit that receives light having a wavelength of 835 nm are integrated and integrated. Type light receiving and emitting integrated device). In this structure, it is not necessary to form the light emitting portion and the light receiving portion with different laminated structures, and the manufacturing process is easy. In addition, a surface light emitting part that operates at a low threshold and a highly sensitive surface light receiving part can be formed at the same time, and either performance is not degraded.

  Note that it is desirable that the design wavelength of the DBR and the oscillation wavelength of the surface light emitting unit be matched as much as possible. As a result, a reflecting mirror having a high reflectivity with respect to the oscillation wavelength of the surface light emitting unit can be formed, so that the threshold current of the surface light emitting unit can be reduced.

  In the embodiment of FIG. 1, the active layer is provided in the first resonator (substrate side) and the light absorption layer is provided in the second resonator, but the active layer is provided in the second resonator. It is also possible to provide the light absorption layer in the first resonator.

  1 does not show a current (or light) confinement structure for the active layer 104, the conventional light emitting / receiving device (surface light emitting / receiving integrated element) shown in FIG. It is also possible to use a constriction structure (for example, an ion-implanted high resistance structure, a side etching constriction structure, an Al oxide confinement structure, a buried structure, etc.) used in

  Example 2 of the present invention corresponds to the second mode. FIG. 2 is a diagram showing a light emitting / receiving device (surface type light emitting / receiving integrated element) according to a second embodiment of the present invention. Referring to FIG. 2, in the second embodiment, unlike the first embodiment, the light emitting region 2A and the light receiving region 2B are spatially separated and monolithically integrated on the first conductivity type semiconductor single crystal substrate 201. Has been. In the light emitting region 2A, the first conductivity type lower DBR 202, the first spacer layer 203, the active layer 204, the second spacer layer 205, and the second conductivity type are formed on the first conductivity type semiconductor single crystal substrate 201. The DBR 206, the third spacer layer 207, the light absorption layer 208, the fourth spacer layer 209, and the first conductivity type upper DBR 210 are sequentially stacked. The laminated structure of the light receiving region 2B is the same as the laminated structure of the light emitting region 2A.

  The mesa structure is formed in each of the light emitting region 2A and the light receiving region 2B by etching from the surface of the laminated structure to the middle of the DBR 206 of the second conductivity type. Further, a separation groove 211 is formed between the light emitting region 2A and the light receiving region 2B by etching until reaching the lower DBR 202. In the light receiving region B, the first electrode 111 is formed on the surface of the first conductivity type upper DBR 110 except for the light incident portion. Second electrodes 212 and 213 are formed on the bottom surfaces of the mesa structure of the light emitting region 2A and the light receiving region 2B, respectively. A third electrode 113 is formed on the back surface of the substrate 201.

  In such a structure, when a forward current flows between the second electrode 212 and the third electrode 113, carriers are injected into the active layer 204 to emit light. The light emitted from the active layer 204 resonates in the first resonator and oscillates in the direction perpendicular to the substrate.

  In addition, by applying a reverse bias between the first electrode 111 and the second electrode 213 via the load resistance, a current flows through the load resistance according to the amount of light absorbed by the light absorption layer 208, The amount of light can be detected.

Hereinafter, the configuration of the second embodiment will be described using a more specific example. The first conductivity type semiconductor single crystal substrate 201 is formed of an n-type GaAs substrate, and the first conductivity type lower DBR 202 is formed by alternately stacking n-type GaAs and n-type AlAs for 30.5 periods. It is formed as a DBR. The first spacer layer 203 is formed of Al _0.2 Ga _0.8 As, the active layer 204 is formed of a GaInAs / Al _0.2 Ga _0.8 As multiple quantum well structure, and the second The spacer layer 205 is made of Al _0.2 Ga _0.8 As. Further, the second conductivity type DBR 206 is formed as a p-type DBR by alternately laminating p-type GaAs and p-type AlAs for 12.5 periods. The third spacer layer 207 is made of Al _0.2 Ga _0.8 As, the light absorption layer 208 is made of GaInAs, and the fourth spacer layer 209 is made of Al _0.2 Ga _{0.8 As.} The upper DBR 210 of the first conductivity type formed of As is formed as an n-type DBR by alternately stacking n-type GaAs and n-type AlAs for 10 periods.

  Note that the active layer 204 and the light absorption layer 208 are configured to be located on the antinodes of the standing wave distribution of light.

  A region sandwiched between the lower DBR 202 and the p-type DBR 206 forms a first resonator. The region sandwiched between the p-type DBR 206 and the upper DBR 210 constitutes a second resonator. In Example 2, the lower DBR 202, the p-type DBR 206, the upper DBR 210, and the first resonator were formed with respective layer thicknesses so as to be phase-matched to a wavelength of 950 nm. The second resonator length was a layer thickness that matched the phase to a wavelength of 890 nm. Thereby, two resonance wavelengths formed by optically coupling the first resonator and the second resonator are 951 nm and 933 nm.

  In the light emitting region 2A, since the resonator lengths of the first resonator and the second resonator are different, light having a wavelength of 951 nm on the long wavelength side is mainly confined in the first resonator having a long resonator length. . Since the active layer 204 is provided in the first resonator and the gain peak wavelength of the active layer 204 is in the vicinity of 950 nm, a forward current flows between the second electrode 112 and the third electrode 113. As a result, the light generated in the active layer 204 resonates in the first resonator and oscillates in the direction perpendicular to the substrate 201. At this time, the light intensity in the second resonator is small, and the optical confinement coefficient of the active layer 204 can be kept high. Also, a high-reflectivity reflecting mirror is formed by making the design wavelength of the DBR substantially coincide with the oscillation wavelength of the surface light emitting element (light emitting region 2A). Thereby, the increase in the threshold current of the light emitting region 2A can be suppressed.

  On the other hand, in the light receiving region 2B, when light having a wavelength of 933 nm is incident from the outside, the light having a wavelength of 933 nm is mainly confined in the second resonator. The light absorption layer 208 provided in the second resonator absorbs light having a wavelength of 933 nm. Accordingly, light having a wavelength of 933 nm incident from the outside is resonantly absorbed by the light absorption layer 208. Thereby, a highly sensitive surface light-receiving element can be formed.

  Further, the design wavelength of the DBR is deviated from the wavelength of light received from the outside. Furthermore, the light absorption layer 208 is provided in the second resonator close to the entrance window, and the number of DBR stacks on the upper side of the resonator is reduced. Therefore, the Q value of the resonator is reduced, and the resonance absorption band can be widened.

  As a result of the above operation, the apparatus (element) in FIG. 2 is monolithically integrated on the same substrate with the surface light-emitting unit 2A that emits light with a wavelength of 951 nm and the surface light-receiving unit 2B that receives light with a wavelength of 933 nm. This is a light emitting / receiving device (surface type light emitting / receiving integrated element). In this structure, the surface light-emitting portion 2A and the surface light-receiving portion 2B are formed with the same laminated structure, which facilitates the manufacturing process. Further, by using an asymmetric double resonator structure with the same laminated structure, it is possible to simultaneously realize the low threshold operation of the surface light emitting unit and the high sensitivity of the surface light receiving element.

  In the first embodiment, the light emitting unit and the light receiving unit are combined with one element, but in the second embodiment, the light emitting unit 2A and the light receiving unit 2B are spatially separated. Therefore, it is possible to suppress the noise current generated when the light of the active layer is absorbed by the light receiving layer, the influence of the fluctuation of the output light intensity when external incident light is input to the active layer, and the like.

  Example 3 of the present invention corresponds to the third and eleventh modes. FIG. 3 is a diagram illustrating an optical transceiver module (and an optical communication system) according to a third embodiment of the present invention. That is, FIG. 3 is a diagram showing an optical transmission / reception module using the surface light emitting / receiving integrated device of Example 2, and further an optical communication system using this optical transmission / reception module. In FIG. Modules 301 and 302 are connected by a single-core optical fiber 303, and optical communication is possible in both directions.

  In the optical transceiver module 301, the surface-type light receiving / emitting integrated element 304a of the second embodiment is used. The VCSEL drive circuit 305 modulates the intensity of the laser beam to be output by modulating the current injected into the active layer of the surface light emitting and receiving integrated element 304 in accordance with the electric signal input from the outside. At this time, the wavelength of the output laser beam is λ1 (for example, 951 nm). The optical signal having the wavelength λ 1 output from the planar light emitting and receiving integrated element 304 a is coupled to the optical fiber 303 through the optical coupling / branching element 307, guided through the optical fiber 303, and transmitted to the optical transceiver module 302 on the opposite side. Entered.

  Further, the surface type light emitting / receiving integrated element 304b of the optical transceiver module 302 outputs a laser beam having a wavelength λ2 (for example, 933 nm), and an optical signal having the wavelength λ2 that reaches the optical transceiver module 301 through the optical fiber 303 is guided. Then, the light is input through the optical coupling / branching element 307 to the light receiving unit of the surface light receiving and emitting integrated element 304a. The light receiving unit of the surface light emitting and receiving integrated element 304a provided in the optical transceiver module 301 resonantly absorbs light of wavelength λ2 and converts the optical signal into an electrical signal. The electrical signal output from the light receiving unit of the surface-type light receiving / emitting integrated element 304a is subjected to signal amplification, waveform shaping, and the like in the receiving circuit 306, and is output to the outside from the optical transceiver module 301.

  On the other hand, the surface-type light receiving / emitting integrated element 304b provided in the optical transceiver module 302 is configured to output laser light having a wavelength λ2 and resonantly absorb light having a wavelength λ1.

  As the optical coupling / branching element 307, a waveguide structure, a hologram element, a diffraction grating, an interferometer, or the like can be used.

  The optical transmission / reception modules 301 and 302 according to the third embodiment include a surface light emitting / receiving integrated element 304 in which a surface light emitting element (light emitting region) and a surface light receiving element (light receiving region) are monolithically integrated. Can be reduced in size. In addition, as described in the second embodiment, the surface-type light receiving / emitting integrated element 304 used in the third embodiment is manufactured by using the same structure for a low-threshold surface light-emitting element and a highly sensitive surface light-receiving element. Can be manufactured easily. Therefore, the cost can be reduced without impairing the performance of the optical transceiver module.

  In Example 3, the element of Example 2 is used as the planar light emitting and receiving integrated element 304. However, the element of Example 1 can also be used.

  The optical communication system of FIG. 3 shows a configuration example of single-channel bidirectional communication. However, bidirectional communication may be performed by a parallel transmission method by arraying the surface-type light receiving and emitting integrated elements 304. Is possible. Thereby, a large-capacity optical communication system can be configured in a small size and at low cost.

  Example 4 of the present invention corresponds to the fourth mode. FIG. 4 is a diagram showing a light receiving and emitting device (surface-type light receiving and emitting integrated element) according to Example 4 of the present invention. In FIG. 4, the surface light-receiving unit can function as a light-receiving element that monitors the light amount of the surface light-emitting unit. Referring to FIG. 4, a first conductivity type lower DBR 402, a first spacer layer 403, a light absorption layer 404, a second spacer layer 405, a second conductivity type are formed on a first conductivity type semiconductor single crystal substrate 401. The DBR 406, the third spacer layer 407, the active layer 408, the fourth spacer layer 409, and the first conductivity type upper DBR 410 are sequentially stacked.

Hereinafter, the configuration of the fourth embodiment will be described using a more specific example. The first conductivity type semiconductor single crystal substrate 401 is formed of an n-type GaAs substrate, and the first conductivity type lower DBR 402 is formed by alternately stacking n-type GaAs and n-type AlAs for 30.5 periods. It is formed as a type DBR. In addition, the first spacer layer 403 is formed of Al _0.2 Ga _0.8 As, the light absorption layer 404 is formed of a GaInAs / Al _0.2 Ga _0.8 As multiple quantum well structure, and the second The spacer layer 405 is made of Al _0.2 Ga _0.8 As. The second conductivity type DBR 406 is formed as a p-type DBR by alternately stacking 10.5 periods of p-type GaAs and p-type AlAs. The third spacer layer 407 is formed of Al _0.2 Ga _0.8 As, the active layer 408 is formed of a GaInAs / Al _0.2 Ga _0.8 As multiple quantum well structure, The spacer layer 409 is formed of Al _0.2 Ga _0.8 As, and the first conductivity type upper DBR 410 is formed as an n-type DBR by alternately stacking n-type GaAs and n-type AlAs for 22 periods. Yes.

  A region sandwiched between the lower DBR 402 and the p-type DBR 406 constitutes a first resonator. The region sandwiched between the p-type DBR 406 and the upper DBR 410 constitutes a second resonator. The lower DBR 402, the p-type DBR 406, the upper DBR 410, and the second resonator were formed with respective layer thicknesses so as to be phase-matched to a wavelength of 950 nm. The first resonator length was a layer thickness that matched the phase to a wavelength of 890 nm. Thereby, two resonance wavelengths formed by optically coupling the first resonator and the second resonator are 952 nm and 933 nm.

  In Example 4, the active layer 408 is provided in the second resonator to form a surface light emitting portion, and the light absorbing layer 404 is provided in the first resonator to form a surface light receiving portion. ing.

  In Example 4, the light absorption layer 404 has the same or smaller band gap as that of the active layer 408, and absorbs light generated in the active layer 408.

  In the embodiment of FIG. 4, since the resonator lengths of the first resonator and the second resonator are different, light having a wavelength of 952 nm on the long wavelength side is mainly transmitted to the second resonator having a long resonator length. Be trapped. Since the active layer 408 is provided in the second resonator, the coupling efficiency between the active layer 408 and the light is high.

  The light absorption layer 404 provided in the first resonator can absorb light having a wavelength of 952 nm. Therefore, by detecting the current generated by the light absorption in the light absorption layer 404, it is possible to monitor the laser light quantity of the surface light emitting unit. That is, in FIG. 4, the surface light-receiving unit can function as a light-receiving element that monitors the light amount of the surface light-emitting unit.

  More specifically, in FIG. 4, a mesa structure is formed by etching from the surface of the laminated structure to the middle of the second conductivity type DBR 406, and a light emitting portion is formed on the surface of the upper DBR 410 of the first conductivity type. Except for this, the first electrode 111 is formed. A second electrode 112 is formed on the bottom surface of the mesa structure. A third electrode 113 is formed on the back surface of the substrate 401.

  In such a structure, when a forward current flows between the first electrode 111 and the second electrode 112, carriers are injected into the active layer 408 to emit light. The light emitted from the active layer 408 resonates in the second resonator and oscillates in the direction perpendicular to the substrate. That is, the active layer 408 is provided in the second resonator to form a surface light emitting unit.

  Further, by applying a reverse bias between the second electrode 112 and the third electrode 113 via the load resistance, a current flows through the load resistance in accordance with the amount of light absorbed by the light absorption layer 404, The amount of light can be detected. That is, the light absorption layer 404 is provided in the first resonator to form a surface light-receiving portion.

  In Example 4, since the resonator lengths of the first resonator and the second resonator are different, the confinement of light with a wavelength of 952 nm is weak in the first resonator. Accordingly, the light generated in the active layer 408 is not excessively absorbed, and an increase in the threshold current of the surface light emitting unit is suppressed. That is, by controlling the amount of deviation of the resonator length of the first resonator and the second resonator, and the number of lamination periods of the DBR 406 provided between the first resonator and the second resonator, The ratio of light coupled to the active layer 408 and the ratio of light coupled to the light absorption layer 404 can be easily adjusted. As a result, it is possible to simultaneously obtain the necessary and sufficient light amount monitor signal and the low threshold current operation of the surface light emitting unit.

  The light absorption layer 404 is not necessarily provided at the antinode position of the optical standing wave distribution in the first resonator. The amount of light absorption of the light absorption layer 404 can also be reduced by shifting from the position of the belly.

  Example 5 of the present invention corresponds to the fifth mode. FIG. 5 illustrates an optical transmission module according to the fifth embodiment. In FIG. 5, the optical transmission module 501 uses the surface-type light receiving / emitting integrated element 502 of Example 4 as a light source.

  In the optical transmission module according to the fifth embodiment, the drive circuit 503 modulates the current injected into the active layer 408 of the surface light emitting and receiving integrated element 502 in accordance with an electric signal input from the outside, and outputs the laser light. Modulate intensity. In addition, a monitor current corresponding to the amount of laser light is output to the receiving circuit 504 from the light absorption layer 404 integrated in the planar light emitting and receiving integrated element 502. The reception circuit 504 performs current-voltage conversion and signal amplification of the monitor current, and outputs a monitor signal to an APC (Auto Power Control) circuit 505. The APC circuit 505 feedback-controls the current value output from the drive circuit 503 so that the monitor signal becomes a certain value. Thereby, even when an environmental temperature change or an element change with time occurs, a constant laser light signal can be output from the optical transmission module 501.

  The optical transmission module 501 of the fifth embodiment includes the surface light emitting / receiving integrated element 502 in which the surface light emitting portion and the monitor light receiving portion are monolithically integrated, so that the number of components is small and the mounting cost can be reduced.

  Even when parallel light transmission is performed by arraying surface light emitting units (surface light emitting elements), a monitor light receiving element is built in each surface light emitting element, so that crosstalk between the surface light emitting elements is reduced. There is no influence and the light output can be easily controlled individually.

  Further, adjacent to the element of the fourth embodiment, similarly to the second embodiment, it is also possible to monolithically integrate the surface light-receiving portions that receive optical signals from the outside on the same substrate. As a result, an optical transmission / reception module including an APC-controlled surface light emitting unit and a surface light receiving unit can be configured.

  Example 6 of the present invention corresponds to the seventh mode. FIG. 6 is a diagram showing a light receiving device (surface type light receiving element) according to a sixth embodiment of the present invention. Referring to FIG. 6, a first conductivity type lower DBR 602, a first spacer layer 603, a first light absorption layer 604, a second spacer layer 605, a first conductivity type semiconductor single crystal substrate 601, A two-conductivity type DBR 606, a third spacer layer 607, a second light absorption layer 608, a fourth spacer layer 609, and a first conductivity type upper DBR 610 are sequentially stacked.

  Then, the mesa structure is formed by etching from the surface of the stacked structure to the middle of the second conductivity type DBR 606, and the first electrode is formed on the surface of the first conductivity type upper DBR 610 except for the light incident portion. 111 is formed. A second electrode 112 is formed on the bottom surface of the mesa structure. A third electrode 113 is formed on the back surface of the substrate 601.

Hereinafter, the configuration of the sixth embodiment will be described using a more specific example. The first-conductivity-type semiconductor single crystal substrate 601 is formed of an n-type GaAs substrate, and the lower DBR 602 is formed by alternately stacking n-type GaAs and n-type Al _0.9 Ga _0.1 As for 30.5 periods. Thus, an n-type DBR is formed. The first spacer layer 603 is formed of Al _0.2 Ga _0.8 As, and the first light absorption layer 604 is formed of a GaInAs / Al _0.2 Ga _0.8 As multiple quantum well structure. The second spacer layer 605 is made of Al _0.2 Ga _0.8 As. Further, the second conductivity type DBR 606 is formed as a p-type DBR by alternately laminating p-type GaAs and p-type Al _0.9 Ga _0.1 As for 15.5 periods. The third spacer layer 607 is formed of Al _0.2 Ga _0.8 As, and the second light absorption layer 608 is formed of a GaInAs / Al _0.2 Ga _0.8 As multiple quantum well structure. The fourth spacer layer 609 is formed of Al _0.2 Ga _0.8 As, and the upper DBR 610 is formed by alternately stacking 10 periods of n-type GaAs and n-type Al _0.9 Ga _0.1 As. It is formed as an n-type DBR.

  A region sandwiched between the lower DBR 602 and the p-type DBR 606 constitutes a first resonator. The region sandwiched between the p-type DBR 606 and the upper DBR 610 constitutes a second resonator. The lower DBR 602, the p-type DBR 606, and the upper DBR 610 were formed with layer thicknesses so as to be phase-matched to a wavelength of 950 nm. The first resonator length was a layer thickness that matched the phase to a wavelength of 900 nm, and the second resonator length was a layer thickness that matched the phase to a wavelength of 1000 nm. Thereby, two resonance wavelengths formed by optically coupling the first resonator and the second resonator are 963 nm and 937 nm.

  In the sixth embodiment, two surface-type light receiving portions that can independently receive two different wavelengths are integrated. That is, the first light absorption layer 604 is provided in the first resonator, and the second light absorption layer 608 is provided in the second resonator, so that two surface light receiving units are formed.

  And the 1st light absorption layer 604 and the 2nd light absorption layer 608 are provided so that it may each be located in the antinode of optical standing wave distribution. The first light absorption layer 604 is made of a material that absorbs light having a resonance wavelength of 937 nm on the short wavelength side, and the second light absorption layer 608 is a material that absorbs light having a resonance wavelength of 963 nm on the long wavelength side. It is configured.

  In such a configuration, when light having a wavelength of 937 nm is incident from the outside, the light having a wavelength of 937 nm is confined by resonating with the first resonator having a short resonator length, and the light intensity is reduced in the second resonator. . Therefore, light having a wavelength of 937 nm is resonantly absorbed by the first light absorption layer 404 provided in the first resonator. On the other hand, when 963 nm light is incident from the outside, the light having a wavelength of 963 nm is confined in the second resonator having a short resonator length. Therefore, light having a wavelength of 963 nm is resonantly absorbed by the second light absorption layer 408 provided in the second resonator. Thereby, two different wavelengths of light can be selected and received by the same element.

  Note that when light having a wavelength of 937 nm is incident, the light is also absorbed by the second light absorption layer 404 provided in the second resonator. However, since the light intensity of the light having a wavelength of 937 nm is reduced by about 1 to 2 digits in the second resonator as compared with that in the first resonator, the influence of crosstalk can be reduced.

  In Japanese Patent Application Laid-Open No. 11-330532, which is a conventional technique, in order to receive light of a plurality of wavelengths, light absorption layers having different band gaps are stacked in order of increasing band gap from the light incident side. Thus, light is absorbed from above in the order of short wavelength and detected individually. On the other hand, the present invention can be operated even when the band gaps of the first light absorption layer 604 and the second light absorption layer 608 are the same. In other words, the two wavelengths can be confined in separate resonators by the asymmetric double resonator structure, so that the light absorption layers 604 and 608 provided in each resonator can be detected individually.

  It is also possible to form an array structure in which the light receiving device (surface type light receiving element) of the sixth embodiment is integrated on the same substrate. In addition, the light receiving device (surface type light receiving element) of Example 6 and the surface type light emitting element, or the surface type light receiving and emitting integrated element of Example 4 (surface type light receiving and emitting integrated element in which monitor light receiving elements are integrated) are provided. Alternatively, they can be integrated on the same substrate. According to the present invention, since different functional parts on the same substrate can be formed with the same laminated structure, the manufacturing process is facilitated.

  Example 7 of the present invention corresponds to the eighth and eleventh aspects. FIG. 7 is a diagram illustrating an optical communication system according to a seventh embodiment. The optical communication system in FIG. 7 is configured by connecting an optical transmission module 701 and an optical reception module 702 with a single-core optical fiber 703.

  Here, in the optical transmission module 701, a surface light emitting element array 704 in which two surface light emitting elements (VCSEL) are monolithically integrated is used as a light source. The two VCSELs have different oscillation wavelengths and oscillate at wavelengths of λ1 and λ2, respectively. As the two-wavelength VCSEL array, a VCSEL having a double resonator structure can be used. Each VCSEL is driven by a drive circuit 705 in accordance with an electric signal input from the outside, and the laser light intensity is modulated. The optical signals output from each VCSEL are collected by an optical coupler 706 and coupled to one optical fiber. The optical signals having the wavelengths λ1 and λ2 are input to the optical receiving module 702 through the optical fiber 703, respectively.

  In the optical receiving module 702, the surface light receiving element 707 described in the sixth embodiment of the present invention is used as the light receiving element. In the surface-type light receiving element 707, light of wavelengths λ1 and λ2 is absorbed by separate light absorption layers, so that optical signals of wavelengths λ1 and λ2 can be separated and detected. An electrical signal corresponding to the optical signals of wavelengths λ1 and λ2 is output from the surface light receiving element 707 to the receiving circuit 708, and signal amplification, waveform shaping, and the like are performed by the receiving circuit 708 and output from the optical receiving module 702 to the outside. The The optical communication system of the seventh embodiment is a wavelength division multiplex transmission system in which two different wavelengths are transmitted through one optical fiber.

  Since the optical receiving module 702 of the seventh embodiment includes the surface light receiving element 707 having a wavelength separation function, it is not necessary to provide an optical branching element. Therefore, the optical receiver module 702 can be reduced in size and cost.

  The eighth embodiment of the present invention corresponds to the ninth and eleventh aspects. FIG. 8 is a diagram illustrating an optical communication system according to an eighth embodiment. The optical communication system in FIG. 8 is configured by connecting an optical transmission module 801 and an optical reception module 802 with a single-core optical fiber 803.

  Here, the optical transmission module 801 uses a surface light emitting element (VCSEL) 804 that modulates the wavelength of the output laser light as a light source.

  The VCSEL 804 that performs wavelength modulation operation includes a first semiconductor multilayer reflector, a first resonator, a second semiconductor multilayer reflector, a second resonator, and a third semiconductor multilayer reflector on a substrate. An active layer is provided in one of the first resonator and the second resonator, a light absorption layer is provided in the other, and a voltage is applied to the active layer and the light absorption layer independently. The electrode which can be provided is provided. The VCSEL has two resonance modes with different wavelengths, and the active layer has a higher gain in the wavelength corresponding to the resonance mode on the short wavelength side than the wavelength corresponding to the resonance mode on the long wavelength side. The light absorption layer has a small absorption coefficient at a wavelength corresponding to two resonance modes when an electric field is not applied, and is shorter than a wavelength corresponding to a resonance mode on a long wavelength side when an electric field is applied. The absorption coefficient is larger at the wavelength corresponding to the resonance mode.

  In the VCSEL 804, the gain of the active layer is higher at the resonance wavelength on the short wavelength side than on the resonance wavelength on the long wavelength side. Therefore, when no electric field is applied to the light absorption layer, the VCSEL 804 Laser oscillation at wavelength. When a reverse bias is applied to the light absorption layer, the absorption coefficient increases with respect to the resonance wavelength on the short wavelength side, so that the oscillation wavelength of the VCSEL 804 shifts to the resonance wavelength on the long wavelength side. Accordingly, the laser light of the VCSEL 804 can be wavelength-modulated by modulating the bias applied to the light absorption layer.

  The rate of change of the absorption coefficient when an electric field is applied to the light absorption layer can be made higher than the relaxation oscillation frequency of the semiconductor laser. In addition, the laser oscillation state is always maintained in the wavelength modulation, and the change in carrier density in the active layer can be suppressed. Therefore, no time is required for accumulating carriers in the active layer, and modulation can be performed at a higher speed. As a result, a large-capacity transmission light source having a transmission capacity per channel exceeding 10 Gbps (for example, 40 Gbps) can be realized with a simple configuration without using an external modulator.

  The DC power source 805 injects a constant current into the active layer of the VCSEL 804 to cause laser oscillation. Further, the modulation bias power source 806 modulates the reverse bias applied to the light absorption layer of the VCSEL 804 in accordance with an electric signal input from the outside. Thus, in the eighth embodiment, the oscillation wavelength of the VCSEL is modulated between λ1 and λ2 with a transmission capacity of 40 Gbps per single channel.

  In the optical receiver module 802, an optical signal guided through the optical fiber cable 803 is input to the surface light receiving element 807. As the surface light-receiving element 807, the surface light-receiving element described in Example 6 of the present invention is used. In the surface-type light receiving element 807, light of wavelengths λ1 and λ2 is absorbed by separate light absorption layers, so that optical signals of wavelengths λ1 and λ2 can be separated and detected. Electric signals corresponding to the optical signals of wavelengths λ1 and λ2 are output from the surface light receiving element 807 to the receiving circuit 808, and the receiving circuit 808 performs current-voltage conversion and signal amplification. A signal output from the reception circuit 808 is input to the difference calculation circuit 809. The difference calculation circuit 809 obtains the difference between the signal corresponding to the wavelength λ1 and the signal corresponding to the wavelength λ2.

  Since the VCSEL 804 of the optical transmission module 801 is output at one of the wavelengths λ1 and λ2, when the optical signal having the wavelength λ1 is received, the optical signal having the wavelength λ2 is not received. Therefore, the signal corresponding to the wavelength λ1 and the optical signal corresponding to the wavelength λ2 output from the surface light receiving element 807 are simultaneously output in a state where 0 and 1 are inverted. By taking the difference between these two signals, the influence of noise is canceled and the reception sensitivity can be improved. That is, differential transmission can be realized in optical transmission. This enables high-performance communication with a low code error rate even in high-speed transmission of 40 Gbps.

  Example 9 of the present invention corresponds to the tenth aspect. FIG. 9 is a diagram showing a light emitting / receiving device (surface type light emitting / receiving integrated element) according to Example 9 of the present invention. A feature of the ninth embodiment is that a mixed crystal semiconductor of nitrogen and other group V elements is used as a material for the active layer 904 and the light absorption layer 908. The operation is the same as that of the first embodiment.

  Referring to FIG. 9, a first conductivity type lower DBR 902, a first spacer layer 903, an active layer 904, a second spacer layer 905, an AlAs layer 911, a first conductivity type semiconductor single crystal substrate 901, A two-conductivity type DBR 906, a third spacer layer 907, a light absorption layer 908, a fourth spacer layer 909, and a first conductivity-type upper DBR 910 are sequentially stacked.

  A region sandwiched between the first conductivity type lower DBR 902 and the second conductivity type DBR 906 constitutes a first resonator. The region sandwiched between the second conductivity type DBR 906 and the first conductivity type upper DBR 910 constitutes a second resonator.

  The first mesa structure is formed by etching from the surface of the laminated structure to the middle of the second conductivity type DBR 906. Further, the second mesa structure is formed by etching until reaching the lower DBR 902 with a size larger than that of the first mesa structure. The AlAs layer 911 is selectively oxidized from the side surface of the second mesa structure to form an Al oxidized region 912. The Al oxide region 912 is an insulating layer and functions to confine the current injected into the active layer 904 in the center of the mesa structure. Further, the first electrode 111 is formed on the surface of the first conductivity type upper DBR 910 except for the light emitting portion. A second electrode 112 is formed on the bottom surface of the first mesa structure. A third electrode 113 is formed on the back surface of the substrate 901.

  Examples of mixed crystal semiconductors of nitrogen and other Group V elements include GaNAs, GaInNAs, GaNAsP, GaInNAsP, GaNAsSb, GaInNAsSb, GaNAsPSb, and GaInNAsPSb. The mixed crystal semiconductor is characterized in that it is a long wavelength band material system capable of crystal growth on a GaAs substrate.

Hereinafter, the configuration of the ninth embodiment will be described using a more specific example. The first conductivity type semiconductor single crystal substrate 901 is composed of an n-type GaAs substrate, and the first conductivity type lower DBR 902 alternately includes n-type GaAs and n-type Al _0.9 Ga _0.1 As. It is formed by laminating 35.5 periods. The first spacer layer 903 is formed of GaAs, the active layer 904 is formed of a GaInNAs / GaAs multiple quantum well structure, and the second spacer layer 905 is formed of GaAs. The second conductivity type DBR 906 is formed by alternately laminating p-type GaAs and p-type Al _0.9 Ga _0.1 As for 12.5 periods. The third spacer layer 907 is formed of GaAs, the light absorption layer 908 is formed of a GaInNAs / GaAs multiple quantum well structure, the fourth spacer layer 909 is formed of GaAs, and has a first conductivity type. The upper DBR 910 is formed by alternately stacking n-type GaAs and n-type Al _0.9 Ga _0.1 As for 10 periods.

  In the ninth embodiment, the lower DBR 902, the p-type DBR 906, the upper DBR 910, and the first resonator have respective layer thicknesses so as to be phase-matched to a wavelength of 1309 nm. The second resonator length was a layer thickness that matched the phase to a wavelength of 1240 nm. Thereby, the two resonance wavelengths formed by optically coupling the first resonator and the second resonator are 1310 nm and 1291 nm. Therefore, in the ninth embodiment, laser light having a wavelength of 1310 nm can be output and light having a wavelength of 1291 nm can be received.

  GaInNAs, which is a mixed crystal semiconductor of nitrogen and another group V element, can increase the confinement barrier height of conduction band electrons to a barrier layer such as GaAs as high as 300 meV or more, so that electron overflow from the well layer is prevented. Suppressed and has good temperature characteristics. Further, it can be epitaxially grown on a high reflectivity and high thermal conductivity DBR in which GaAs and AlAs or GaAs and AlGaAs are stacked, and a VCSEL having good performance in a long wavelength band can be formed.

  Further, by using a mixed crystal semiconductor of nitrogen and other group V elements such as GaInNAs in the active region, the VCSEL can be operated in the vicinity of a wavelength of 1.31 μm where the dispersion of the quartz optical fiber is zero. In the present invention, optical communication is performed using light of two different wavelengths, but signal degradation due to chromatic dispersion after quartz optical fiber transmission can be suppressed by using a 1.3 μm band with small chromatic dispersion.

In the ninth embodiment, in the planar light emitting and receiving integrated device of the first embodiment, the active layer and the light absorption layer are described using an example of a mixed crystal semiconductor containing nitrogen and another group V element. In the surface light-receiving / emitting integrated device described in Example 4 and the surface light-receiving device described in Example 6, a mixed crystal semiconductor containing nitrogen and other group V elements is used for the active layer and the light absorption layer. it can.

It is a figure which shows the light emitting / receiving apparatus (surface type light emitting / receiving integrated element) of Example 1 of this invention. It is a figure which shows the light emitting / receiving apparatus (surface type light emitting / receiving integrated element) of Example 2 of this invention. It is a figure which shows the optical transmission / reception module (further optical communication system) of Example 3 of this invention. It is a figure which shows the light receiving and emitting apparatus (surface type light receiving and emitting integrated element) of Example 4 of this invention. FIG. 10 illustrates an optical transmission module according to a fifth embodiment. It is a figure which shows the light-receiving device (surface type light receiving element) of Example 6. FIG. 10 is a diagram illustrating an optical communication system according to a seventh embodiment. FIG. 10 is a diagram illustrating an optical communication system according to an eighth embodiment. It is a figure which shows the light emitting / receiving apparatus (surface type light emitting / receiving integrated element) of Example 9 of this invention. FIG. 3 is a view showing a light intensity distribution in the surface light emitting / receiving integrated device of Example 1.

Explanation of symbols

101, 201, 401, 601, 901 Substrate 102, 202, 402, 602, 902 Lower DBR
103, 203, 403, 603, 903 First spacer layer 104, 204, 408, 904 Active layer 105, 205, 405, 605, 905 Second spacer layer 106, 206, 406, 606, 906 DBR
107, 207, 407, 607, 907 Third spacer layer 108, 208, 404, 908 Light absorbing layer 109, 209, 409, 609, 909 Fourth spacer layer 110, 210, 410, 610, 910 Upper DBR
111 First electrode 112, 212, 213 Second electrode 113 Third electrode 2A Light emitting region 2B Light receiving region 211 Separation groove 301 First optical transceiver module 302 Second optical transceiver module 303 Optical fibers 304a, 304b Surface type Light receiving / emitting integrated element 305 VCSEL driving circuit 306 Receiving circuit 307 Optical coupling / branching element 501 Optical transmission module 502 Planar type light receiving / emitting integrated element 503 Driving circuit 504 Receiving circuit 505 APC circuit 604 First light absorption layer 608 Second light absorption Layer 701 Optical transmission module 702 Optical reception module 703 Optical fiber 704 VCSEL array 705 Drive circuit 706 Optical coupler 707 Surface light receiving element 708 Reception circuit 801 Optical transmission module 802 Optical reception module 803 Optical fiber 804 VCSEL
805 DC power supply 806 Modulation bias power supply 807 Surface light receiving element 808 Reception circuit 809 Difference operation circuit 911 AlAs layer 912 Al oxidation region

Claims (6)

A first semiconductor multilayer film reflector, a first resonator, a second semiconductor multilayer film reflector, a second resonator, and a third semiconductor multilayer film reflector are provided on a substrate. And the second resonator are provided with an active layer, and the other resonator is provided with a light absorption layer, which is different from the first resonator and the second resonator. A surface light emitting device having a resonator length and a different resonance wavelength and provided with an electrode capable of applying a voltage to the active layer; and the same stacked structure as the surface light emitting device on the substrate. The surface light-receiving element provided with an electrode capable of applying a voltage to the light absorption layer is monolithically integrated. With light emitting and receiving device according to claim 1 Symbol mounting, the optical transceiver module, characterized that it is capable of optical bidirectional transmission and reception. 2. The light emitting / receiving device according to claim 1, wherein the light absorption layer is made of a material that absorbs light generated in the active layer. The light emitting / receiving device according to claim 3 and an active signal of the light emitting / receiving device by an electric signal output from the light absorption layer of the light emitting / receiving device so that the light intensity output from the light emitting / receiving device is constant. An optical transmission module comprising current control means for controlling a current to be injected. 4. The light emitting / receiving device according to claim 1 or 3, wherein the active layer and / or the light absorbing layer is made of a mixed crystal semiconductor containing nitrogen and another group V element. Optical transceiver module of claim 2 or the optical communication system, characterized in that the optical transmission module according to claim 4 wherein is used.

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