JP2009105240A - Semiconductor light-emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting apparatus capable of temperature-compensating the impedance characteristics and capable of suppressing the occurrence of high-frequency noises and degradation of drive signals. <P>SOLUTION: The semiconductor light-emitting apparatus 10 comprises: a disc-like stem 100 made from metal; a submount 110 mounted on the stem 100; a VCSEL120 that is fixed on the submount 110 and emits laser beam; a resistive element 130 which changes its resistance value according to ambient temperature; a light-receiving element 140 for receiving part of the laser beam; a cap 150 which covers the stem 100; and lead terminals 160-166 of conductive metal attached to the stem 100. The resistive element 130 is connected in series to the VCSEL120 and temperature-compensates the impedance value of the semiconductor light-emitting apparatus 10. Thus, matching with an external drive circuit is maintained even at low temperature or a high temperature, thereby suppressing the occurrence of high-frequency noises caused by reflection. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device including a semiconductor light emitting element, and more particularly to a technique for compensating for temperature characteristics of a surface emitting semiconductor laser element and preventing signal deterioration due to impedance mismatching.

  Surface-emitting semiconductor laser (Vertical-Cavity Surface-Emitting Laser diode: hereinafter referred to as VCSEL) is an evaluation and light source in a wafer state that can easily obtain a circular light spot with low threshold current and low power consumption. It has an excellent feature not found in edge-emitting semiconductor lasers, such as a two-dimensional array. Taking advantage of these features, demand as a light source is particularly expected in technical fields such as optical communication and optical recording.

  When a semiconductor light emitting element such as a VCSEL is used as a light source in the communication field, in order to suppress communication errors, it is necessary to suppress the generation of high frequency noise that causes intersymbol interference and the deterioration of drive signals. For this reason, several techniques disclose a technique for absorbing high-frequency current and a technique for preventing the generation of high-frequency noise by impedance matching.

  Patent Document 1 is a laser diode in which a circuit that absorbs a high-frequency current is connected in parallel to the laser diode. A technique is disclosed in which a high-frequency current is absorbed to suppress an unnecessary carrier density fluctuation and to obtain a good modulation waveform with little intersymbol interference.

  Patent Document 2 is a semiconductor drive circuit including a circuit connected in parallel to a semiconductor laser device, and the circuit includes a capacitor and a resistance element having a positive temperature coefficient connected in series. A technique for suppressing the relaxation oscillation phenomenon in a wide range of temperatures is disclosed.

  Patent Document 3 is a semiconductor light emitting device in which a matching load is connected to a semiconductor laser. For the matching load, a VCSEL whose output port is blocked is used. Thus, a technique for impedance matching with an external drive circuit is disclosed.

  Patent Document 4 is a semiconductor light emitting device in which a substrate is provided with a light emitting element and an impedance function. A technique for forming a light emitting element and a resistance element having an impedance function on the same substrate is disclosed.

JP-A-60-187075 JP-A-2005-302895 US Pat. No. 6,728,280 US Pat. No. 7,049,759

  When the VCSEL is driven at high speed, it is desirable to match the impedance values of the VCSEL and the external drive circuit in order to prevent generation of high frequency noise and deterioration of the drive signal. In the conventional matching method, the impedance value of the VCSEL is compensated by adding a chip resistor to the VCSEL or forming a plurality of resistive elements monolithically on the VCSEL substrate.

  The VCSEL has a temperature characteristic in which the resistance is negative. In other words, the resistance decreases as the operating temperature increases. Since the conventional matching method does not consider the operating temperature of the VCSEL, for example, the temperature coefficient of the added chip resistance is significantly smaller than the temperature coefficient of the VCSEL, or the temperature of the resistance element formed monolithically Since the coefficient has the same negative temperature coefficient as that of the VCSEL, the impedance value fluctuates with a change in temperature, and impedance matching with the drive circuit may not be achieved. As a result, there are problems that high-frequency noise is generated due to reflection of the drive signal, or that the drive signal is deteriorated.

  An object of the present invention is to solve such a problem, and an object of the present invention is to provide a semiconductor light emitting device that compensates the temperature of a VCSEL and prevents generation of high frequency noise and deterioration of a drive signal.

  A semiconductor light emitting device according to the present invention includes a semiconductor light emitting element having a negative temperature characteristic of a resistance, a resistance element electrically connected in series to the semiconductor light emitting element, and fixing the semiconductor light emitting element and the resistance element. The resistance element has a positive temperature characteristic.

  Preferably, the slope of the negative temperature coefficient of the semiconductor light emitting element is substantially equal to the slope of the positive temperature coefficient of the resistance element. Preferably, the positive temperature coefficient of the resistance element has a linear characteristic at least within a temperature range of −40 ° C. to + 120 ° C. More preferably, the temperature coefficient of the resistance element is +300 ppm / ° C. or higher and +5000 ppm / ° C. or lower. The semiconductor light emitting device is a group III-V compound semiconductor, for example, a surface emitting semiconductor laser device such as GaAs or AlGaAs. The resistance element is a resistance element in which conductive powder is dispersed in barium titanate or a polymer. Further, the substrate is preferably made of a ceramic insulating substrate having high thermal conductivity, and it is desirable to thermally couple the semiconductor light emitting element and the resistance element. Furthermore, the series resistance of the semiconductor light emitting element and the resistance element is preferably 100Ω within a temperature range of −40 ° C. to 120 ° C.

  An optical transmission module according to the present invention includes a semiconductor light emitting device having the above characteristics and a drive circuit connected to the semiconductor light emitting device and driving a semiconductor light emitting element, and the impedance of the semiconductor light emitting device is substantially equal to the impedance value of the drive circuit. equal. Preferably, the drive circuit drives the semiconductor light emitting element at 5 GHz or more.

  According to the present invention, the operating characteristic of the semiconductor light emitting element can be temperature compensated by connecting the resistance element having the temperature coefficient opposite to the temperature coefficient of the semiconductor light emitting element in series with the semiconductor light emitting element. Thereby, even if the operating temperature changes, the series resistance or impedance of the semiconductor light emitting device can be kept constant, and as a result, impedance matching with the drive circuit can be compensated. Thereby, it is possible to prevent the generation of high frequency noise and the deterioration of the drive signal due to impedance mismatch.

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

  FIG. 1 is a side sectional view showing a schematic configuration of a semiconductor light emitting device according to an embodiment of the present invention. The semiconductor light emitting device 10 according to the present embodiment includes a metal disc-shaped stem 100, a submount 110 mounted on the stem 100, a VCSEL 120 fixed on the submount 110 and emitting laser light, and a resistance. A resistance element 130 having a positive temperature coefficient, a light receiving element 140 that receives a part of laser light emitted from the VCSEL 120, a cap 150 that covers the stem 100, and a lead made of a plurality of conductive metals attached to the stem 100. Terminals 160, 162, 164, 166 are included.

  A plurality of through holes (not shown) are formed in the stem 100, and lead terminals 160 to 166 are inserted into the respective through holes. The leads 160 to 166 are electrically insulated from the stem 100 in the through hole by glass resin or the like.

  The VCSEL 120 is connected to the resistance element 130 in series. That is, the p-side electrode of the VCSEL 120 is connected to one electrode of the resistance element 130, and the other electrode of the resistance element 130 is connected to the lead terminal 160. Further, the n-side electrode of the VCSEL 120 is electrically connected to the lead terminal 162 via the electrode thin film 112 formed at the center of the upper surface of the submount 110.

  The light receiving element 140 is composed of, for example, a photodiode or a phototransistor, and the n-side electrode is electrically connected to the lead terminal 164 and the p-side electrode is electrically connected to the lead terminal 166. The light receiving element 140 receives the reflected light of the VCSEL 120 reflected by the flat glass 154, outputs the output signal from the lead terminals 164 and 166, and supplies the output signal to the APC drive circuit that monitors the optical output of the VCSEL 120.

  Normally, the n-side electrode (cathode) of the VCSEL 120 and the p-side electrode (anode) of the light receiving element 140 are connected to a common lead terminal. However, when the VCSEL 120 is driven at a high speed, generation of high-frequency noise and deterioration of the drive signal are prevented. In order to suppress this, the lead terminal 162 used for the n-side electrode of the VCSEL 120 and the lead terminal 166 used for the p-side electrode of the light receiving element 140 are made separate.

  The cap 150 is a cup-shaped metal member, and a leg portion 152 at the periphery thereof is fixed to the stem 100 by welding or the like. A circular opening is formed in the upper center of the cap 150, and a flat glass 154 that transmits laser light emitted from the VCSEL 120 is attached to the inside of the opening. Thus, the VCSEL 120, the resistance element 130, and the light receiving element 140 are sealed in the internal space of the cap 150. Note that the sealing does not need to be completely airtight.

  FIG. 2 is a plan view showing the arrangement of each element fixed on the submount. In the figure, the electrode portions of the VCSEL 120, the resistance element 130, and the light receiving element 140 and the electrode thin film 112 formed on the surface of the submount 110 are hatched. The submount 110 mounted on the stem 100 is preferably made of a ceramic substrate such as aluminum nitride or alumina having high thermal conductivity. The submount 110 has a rectangular shape, and a rectangular electrode thin film 112 is formed at substantially the center thereof. The VCSEL 120 is fixed on the electrode thin film 112 via a conductive adhesive or the like. The electrode thin film 112 is preferably a metal material such as Au that is resistant to oxidation. The resistance element 130 is fixed to one side of the VCSEL 120 and the light receiving element 140 is fixed to the other side by an adhesive or the like. The VCSEL 120 and the resistance element 130 are thermally coupled to each other via the submount 110, and the VCSEL 120 and the resistance element 130 are placed in a similar temperature environment.

  The n-side electrode of the VCSEL 120 is connected to the electrode thin film 112, and the electrode thin film 112 is connected to the lead terminal 162 by a bonding wire 170a. The p-side electrode of the VCSEL 120 is connected to one electrode 132 of the resistance element 130 by a bonding wire 170b, and the other electrode 134 of the resistance element 130 is connected to the lead terminal 160 by a bonding wire 170c. The n-side electrode 142 of the light receiving element 140 is connected to the lead terminal 164 by a bonding wire 170d, and the p-side electrode 144 is connected to the lead terminal 166 by a bonding wire 170e.

  The resistance element 130 has a positive temperature characteristic and is opposite in sign to the temperature characteristic of the VCSEL 120. As the resistance element 130, for example, a PTC thermistor made of barium titanate or a polymer PTC in which a conductive powder such as carbon is dispersed in a polymer can be used. The resistance element 130 is connected in series with the VCSEL 120 to compensate for a change in resistance due to a temperature change of the VCSEL 120. Therefore, it is desirable that the resistance element 130 has the same temperature environment as that of the VCSEL 120, and the resistance element 130 is fixed at a position as close as possible to the VCSEL 120 on the submount 110. Here, one electrode 132 of the resistance element 130 and the p-side electrode of the VCSEL 120 are connected by a single bonding wire 170b, but may be connected by a plurality of bonding wires in order to improve the thermal coupling between them. Further, in addition to the bonding wire, both may be coupled by a flat metal plate.

  FIG. 3 is a cross-sectional view showing a general configuration of the VCSEL 120. The VCSEL 120 includes an n-side electrode 202 on the back surface of an n-type GaAs substrate 200, and a lower DBR (Distributed Bragg Reflector: distribution) composed of an n-type GaAs buffer layer 204 and an n-type AlGaAs semiconductor multilayer film on the substrate 200. Bragg reflector 206), active region 208, current confinement layer 210 formed by oxidizing the outer edge of p-type AlAs, upper DBR 212 formed of a p-type AlGaAs semiconductor multilayer film, and p-type GaAs contact layer 214. Including semiconductor layers.

  In the semiconductor layer, a ring-shaped groove 216 having a depth reaching from the contact layer 214 to a part of the lower DBR 206 is formed. The groove 216 forms a cylindrical post P that is a laser light emitting portion and an electrode formation region 218. Is prescribed. In addition, an interlayer insulating film 220 is formed on the surface of the semiconductor layer including the groove 216 to protect the semiconductor layer from the outside. A p-side electrode 222 ohmically connected to the contact layer 214 exposed by the contact hole of the interlayer insulating film 220 is provided on the top of the post P. A laser light emission region is defined at the center of the p-side electrode 222. A circular emission port 224 is formed. In addition, a circular electrode pad 226 is formed in the electrode formation region 218 via the interlayer insulating film 220, and the electrode pad 226 is electrically connected to the p-side electrode 222 that is the anode side of the VCSEL 120. The VCSEL 120 thus formed emits a laser beam having a wavelength of about 850 nm from the emission port 224 of the post P.

  FIG. 4 is a diagram showing an equivalent circuit of the VCSEL and the resistance element of the semiconductor light emitting device. Between the lead terminals 160 and 162 of the semiconductor light emitting device 10, a VCSEL 120 that emits laser light and a resistance element 130 that compensates the temperature of the VCSEL 120 are connected in series. In addition, a drive circuit 180 having an output impedance of 100Ω is connected to the lead terminals 160 and 162 of the semiconductor light emitting device 10 via a transmission line 182. Here, the impedance value Z of the semiconductor light emitting device 10 is a combined impedance of the VCSEL 120 and the resistance element 130 and can be derived from the following equation.

  Here, Rv is the resistance value of the VCSEL 120, and Rt is the resistance value of the resistance element 130.

  FIG. 5A is a graph showing the temperature characteristics of the VCSEL. In the figure, the horizontal axis indicates the temperature T, the vertical axis indicates the resistance value [Ω], and the relationship between the temperature T and the resistance value Rv of the VCSEL 120 is illustrated. Since the VCSEL 120 has a negative temperature coefficient, the resistance value Rv decreases as the temperature T increases, and the resistance value Rv increases as the temperature T decreases. The temperature coefficient α of the VCSEL 120 can be derived from the following equation.

  From the above formula, the calculated temperature coefficient α of the VCSEL shown in FIG. 5A can be expressed as about −0.4%, that is, −4000 ppm (parts per million) / ° C. ppm means one millionth. The temperature coefficient α of the VCSEL changes almost linearly in the temperature range of −20 ° C. to 85 ° C.

  FIG. 5B is a graph showing the temperature characteristics of the resistance element. In the figure, the horizontal axis indicates the temperature T, the vertical axis indicates the resistance value [Ω], and the relationship between the temperature T and the resistance value Rv of the resistance element 130 is illustrated. Since the resistance element 130 has a positive temperature coefficient, the resistance value Rt increases when the temperature T increases, and the resistance value Rt decreases when the temperature T decreases. Preferably, the temperature coefficient of the resistance element 130 is equal to the absolute value of the temperature coefficient of the VCSEL, that is, the temperature coefficient α of the resistance element 130 is +4000 ppm / ° C. Further, the temperature coefficient α of the resistance element 130 is equal to that of the VCSEL 120. It is desirable to be linear from −40 ° C. to + 120 ° C., including the operating temperature range.

  If the temperature coefficient α of the VCSEL 120 is −4000 ppm / ° C. and the temperature coefficient α of the resistance element 130 is +4000 ppm / ° C., when both are connected in series, the amount of change in the negative resistance accompanying the temperature change of the VCSEL is the resistance The total impedance value Z of the semiconductor light emitting device 10 can be kept constant by canceling out by the amount of change in the positive resistance of the element.

  The impedance value Z of the semiconductor light emitting device 10 needs to be matched with the impedance value of the drive circuit 180. In particular, when driving at a high speed of 10 GHz or more, it is important in terms of preventing noise and signal deterioration. .

  Since the impedance value including the transmission line 182 connected to the drive circuit 180 is 100Ω, it is desirable that the impedance value Z of the semiconductor light emitting device 10 matches or approximates 100Ω. FIG. 6 is a table showing the relationship between the temperature T and the resistance values Rv and Rt of the VCSEL and the resistance element. For example, when the operating temperature is 24 ° C. (normal temperature), the resistance value Rv of the VCSEL 120 is 49Ω, and the resistance value Rt of the resistance element 130 is 51Ω. Thereby, the impedance value Z of the semiconductor light emitting device 10 becomes 100Ω, which is matched with the impedance value 100Ω of the drive circuit 180.

  For example, when the temperature T decreases to −20 ° C., the resistance Rv of the VCSEL 120 increases to 57Ω, but the resistance Rt of the resistance element 130 decreases to 43Ω, and the impedance value Z of the semiconductor light emitting device 10 remains 100Ω. Be drunk. On the other hand, when the operating temperature T rises to 85 ° C., the resistance Rv of the VCSEL 120 decreases to 38Ω, but the resistance Rt of the resistance element 130 increases to 62Ω, and the impedance value Z of the semiconductor light emitting device 10 remains 100Ω. Be drunk.

  As described above, the semiconductor light emitting device 10 can keep the impedance value Z constant even when the temperature environment changes, and can compensate the impedance matching with the external drive circuit. Thereby, it is possible to prevent the generation of high frequency noise and the deterioration of the drive signal due to impedance mismatch.

  In the above embodiment, an example of a single spot where the VCSEL 20 emits laser light from a single post P has been shown, but a multi-spot where a plurality of posts are arranged and laser light is emitted therefrom may be used. Further, the semiconductor light emitting element is not limited to the VCSEL, and may be another semiconductor light emitting element such as a light emitting diode. The VCSEL used may include a substrate other than the GaAs substrate.

  Next, a module, an optical transmission device, a spatial transmission system, an optical transmission device, etc. using the semiconductor light emitting device of this embodiment will be described with reference to the drawings. FIG. 7A is a cross-sectional view illustrating a package example of a semiconductor light emitting device. In the package 300, the submount 320 for fixing the VCSEL 310 and the resistance element 312 is mounted on a disk-shaped metal stem 330, as in the semiconductor light emitting device of this embodiment. Conductive leads 340 and 342 are inserted into through holes (not shown) formed in the stem 330, one lead 340 is electrically connected to the n-side electrode of the VCSEL, and the other lead 342 is It is electrically connected to the p-side electrode.

  A rectangular hollow cap 350 is fixed on the stem 330, and a ball lens 360 is fixed in an opening 352 at the center of the cap 350. The optical axis of the ball lens 360 is positioned so as to substantially coincide with the center of the VCSEL 310. When a forward voltage is applied between the leads 340 and 342, laser light is emitted from the VCSEL 310 in the vertical direction. The distance between the VCSEL 310 and the ball lens 360 is adjusted so that the ball lens 360 is included within the spread angle θ of the laser light from the VCSEL 310. Further, the cap 350 may include a light receiving element 314 for monitoring the light emission state of the VCSEL 310.

  FIG. 7B is a diagram showing the configuration of another package example. In the package 302 shown in FIG. 7B, the upper surface of the cap 350 has a certain inclination, and the flat glass 362 is fixed inside the central opening 352. Yes. The center of the flat glass 362 is positioned so as to substantially coincide with the center of the VCSEL 310. The distance between the VCSEL 310 and the flat glass 362 is adjusted such that the opening diameter of the flat glass 362 is equal to or larger than the spread angle θ of the laser light from the VCSEL 310. The flat glass 362 can reflect a part of the laser light in a specific direction, and widens an allowable region in which the light receiving element 314 is disposed.

  FIG. 8 is a diagram illustrating an example in which a semiconductor light emitting device is applied as a light source. As shown in FIG. 7A or 7B, the light source device 370 is a collimator lens 372 that receives multi-beam laser light from the package 300 on which the VCSEL is mounted. The light source device 370 rotates at a constant speed, and the light flux from the collimator lens 372 is constant. A latent image is formed based on the reflected light from the polygon mirror 374 that reflects at the divergence angle, the fθ lens 376 that receives the laser light from the polygon mirror 374 and irradiates the reflection mirror 378, the line-like reflection mirror 378, and the reflection mirror 378. A photosensitive drum 380 is provided. As described above, optical information processing such as a copying machine or a printer provided with an optical system for condensing the laser light from the VCSEL on the photosensitive drum and a mechanism for scanning the condensed laser light on the optical drum. It can be used as a light source for the apparatus.

  FIG. 9 is a cross-sectional view showing a configuration when the package of the semiconductor light emitting device shown in FIG. 7A is applied to an optical transmitter. The optical transmission device 400 includes a cylindrical casing 410 fixed to the stem 330, a sleeve 420 integrally formed on the end surface of the casing 410, a ferrule 430 held in the opening 422 of the sleeve 420, and a ferrule 430. The optical fiber 440 to be held is included. An end of the housing 410 is fixed to a flange 332 formed in the circumferential direction of the stem 330. The ferrule 430 is accurately positioned in the opening 422 of the sleeve 420 and the optical axis of the optical fiber 440 is aligned with the optical axis of the ball lens 360. The core wire of the optical fiber 440 is held in the through hole 432 of the ferrule 430.

  The laser light emitted from the surface of the chip 310 is collected by the ball lens 360, and the collected light is incident on the core wire of the optical fiber 440 and transmitted. Although the ball lens 360 is used in the above example, other lenses such as a biconvex lens and a plano-convex lens can be used. Further, the optical transmission device 400 may include a drive circuit for applying an electrical signal to the leads 340 and 342. Furthermore, the optical transmission device 400 may include a reception function for receiving an optical signal via the optical fiber 440.

  FIG. 10 is a diagram showing a configuration when the semiconductor light emitting device shown in FIG. 7 is used in a spatial transmission system. The spatial transmission system 500 includes a package 300, a condenser lens 510, a diffusion plate 520, and a reflection mirror 530. The light condensed by the condenser lens 510 is reflected by the diffusion plate 520 through the opening 532 of the reflection mirror 530, and the reflected light is reflected toward the reflection mirror 530. The reflection mirror 530 reflects the reflected light in a predetermined direction and performs optical transmission.

  FIG. 11A is a diagram illustrating a configuration example of an optical transmission system using a VCSEL as a light source. The optical transmission system 600 receives a light source 610 including a chip 310 on which a VCSEL is formed, an optical system 620 that collects laser light emitted from the light source 610, and the laser light output from the optical system 620. A light receiving unit 630 and a control unit 640 that controls driving of the light source 610 are included. The control unit 640 supplies a drive pulse signal for driving the VCSEL to the light source 610. Light emitted from the light source 610 is transmitted to the light receiving unit 630 via an optical system 620 by an optical fiber, a reflection mirror for spatial transmission, or the like. The light receiving unit 630 detects the received light with a photodetector or the like. The light receiving unit 630 can control the operation of the control unit 640 (for example, the start timing of optical transmission) by the control signal 650.

  FIG. 11B is a diagram illustrating a general configuration of an optical transmission device used in the optical transmission system. The optical transmission device 700 includes a case 710, an optical signal transmission / reception connector joint 720, a light emitting / receiving element 730, an electric signal cable joint 740, a power input unit 750, an LED 760 indicating that an operation is in progress, an LED 770 indicating occurrence of an abnormality, and a DVI. It includes a connector 780 and has a transmission circuit board / reception circuit board inside.

  A video transmission system using the optical transmission apparatus 700 is shown in FIG. The video transmission system 800 uses the optical transmission device shown in FIG. 11B in order to transmit the video signal generated by the video signal generation device 810 to the image display device 820 such as a liquid crystal display. That is, the video transmission system 800 includes a video signal generation device 810, an image display device 820, a DVI electric cable 830, a transmission module 840, a reception module 850, a video signal transmission optical signal connector 860, an optical fiber 870, and a control signal electrical. A cable connector 880, a power adapter 890, and an electric cable 900 for DVI are included.

  The above-described embodiments are illustrative, and the scope of the present invention should not be construed as being limited thereto, and can be realized by other methods within the scope satisfying the constituent requirements of the present invention. Needless to say.

  The semiconductor light emitting device according to the present invention can be used as a light source used in various fields such as optical information processing and optical high-speed data communication.

It is side surface sectional drawing which shows schematic structure of the semiconductor light-emitting device based on the Example of this invention. It is a top view which shows arrangement | positioning of each element mounted in the submount. It is side surface sectional drawing of VCSEL. It is an equivalent circuit which shows a semiconductor light-emitting device. It is a graph which shows the temperature characteristic of VCSEL and a resistive element. 3 is a table showing the relationship between temperature T and impedance value Z. It is a schematic sectional drawing which shows the modification of the package of the semiconductor light-emitting device concerning a present Example. It is a figure which shows the structural example of the light source device which uses VCSEL. It is a schematic sectional drawing which shows the structure of the optical transmitter using the module shown in FIG. It is a figure which shows a structure when the module shown in FIG. 7 is used for a spatial transmission system. FIG. 11A is a block diagram showing a configuration of the optical transmission system, and FIG. 11B is a diagram showing an external configuration of the optical transmission device. It is a figure which shows the video transmission system using the optical transmission apparatus of FIG. 11B.

DESCRIPTION OF SYMBOLS 10: Semiconductor light-emitting device 100: Metal stem 110: Submount 112: Electrode thin film 120: VCSEL 130: Resistance element 140: Light receiving element 150: Cap 152: Flat glass 160-166: Lead terminals 170a-170e: Bonding wire 180: Drive Circuit 182: Transmission path

Claims (14)

A semiconductor light emitting device having a negative temperature characteristic of resistance;
A resistive element electrically connected in series to the semiconductor light emitting element;
A substrate for fixing the semiconductor light emitting element and the resistance element;
The semiconductor light emitting device, wherein the resistance element has a positive temperature characteristic. The semiconductor light emitting device according to claim 1, wherein a slope of the negative temperature coefficient of the semiconductor light emitting element is substantially equal to a slope of the positive temperature coefficient of the resistance element. 3. The semiconductor light emitting device according to claim 1, wherein the positive temperature coefficient of the resistance element has a linear characteristic within a temperature range of at least −40 ° C. to + 120 ° C. 4. 4. The semiconductor light emitting device according to claim 1, wherein the temperature coefficient of the resistance element is +300 ppm / ° C. or more and +5000 ppm / ° C. or less. 5. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting element is a group III-V compound semiconductor surface emitting semiconductor laser element. 6. The semiconductor light-emitting device according to claim 1, wherein the resistance element includes barium titanate. The semiconductor light emitting device according to claim 1, wherein the resistance element is a resistance element in which conductive powder is dispersed in a polymer. The semiconductor light emitting device according to claim 1, wherein the substrate is made of a ceramic insulating substrate having high thermal conductivity, and thermally couples the semiconductor light emitting element and the resistance element. 9. The semiconductor light emitting device according to claim 1, wherein a series resistance of the semiconductor light emitting element and the resistance element is 100Ω within a temperature range of −40 ° C. to 120 ° C. 9. A semiconductor light emitting device according to any one of claims 1 to 9,
A drive circuit connected to the semiconductor light emitting device and driving the semiconductor light emitting element;
An optical transmission module, wherein an impedance of the semiconductor light emitting device is substantially equal to an impedance of the drive circuit. The optical transmission module according to claim 10, wherein the drive circuit drives the semiconductor light emitting element at 5 GHz or more. A semiconductor light emitting device according to any one of claims 1 to 9,
An optical module including an optical member that projects light emitted from a semiconductor light emitting device. An optical space transmission device comprising: the module according to claim 11; and a transmission unit that spatially transmits light emitted from the module. An optical transmission system comprising: the module according to claim 11; and a transmission unit that spatially transmits light emitted from the module.

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