JP2000228556A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device having superior controllability and transmission characteristic for the wave length in which characteristics of a semiconductor laser element and an electric field absorption semiconductor light modulator element are adjusted individually, and there is less deterioration in the transmission characteristic being caused by electrical bonding between the semiconductor laser element and the electric field absorption semiconductor light modulator element. SOLUTION: In a semiconductor laser device provided with a semiconductor laser element 2 emitting laser beam and an electric field absorption semiconductor light modulator element 3 that modulates the laser beam emitted from the semiconductor laser element 2, the semiconductor laser element 2 and the electric field absorption semiconductor light modulator element 3 are placed separately, and further temperature control means 7a and 7b are provided to the semiconductor laser element 2 and the electric field absorption semiconductor light modulator element 3, respectively, to individually control temperature of the semiconductor laser element 2 and the electric field absorption semiconductor light modulator element 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device used for an optical communication system or the like, and more particularly to a semiconductor laser device suitable for wavelength division multiplexing optical communication.

[0002]

2. Description of the Related Art Recent long-distance optical communication systems have long distances.
Along with the increase in capacity, a modulator-integrated semiconductor laser device integrated by combining an electroabsorption type semiconductor optical modulator with a semiconductor laser has a small wavelength chirp at the time of modulation. Has been attracting attention as a key device. FIG. 11 shows an example of “A 10-Gb / s Optical Transmitter Module with a
Monolithically Integrated Electroabsorption Modula
tor with a DFB Laser (IEEE PHOTONICS TECHNOLOGYLET
1 is a cross-sectional view of a semiconductor laser device disclosed in "TERS, VOL. 2, NO. 12, DECEMBER 1990". In the figure, reference numeral 1 denotes a modulator integrated semiconductor laser element, which has a semiconductor laser unit 2 for emitting laser light, and an electric absorption type semiconductor optical modulator unit 3 for modulating the intensity of the laser light. 2 and the electroabsorption type semiconductor optical modulator unit 3 are monolithically integrated. The modulator integrated semiconductor laser device 1 includes an optical waveguide 4, an electrode 5a of a semiconductor laser unit 2, an electrode 5b of an electroabsorption type semiconductor optical modulator unit 3, and a ground electrode 6.
The modulator-integrated semiconductor laser device 1 is fixed to the thermoelectric cooling device 7 at the lower portion, and is housed in the case 8 together with the thermoelectric cooling device 7. Further, an optical fiber 9 is mounted on a side portion of the case 8 so as to penetrate the case 8, and light emitted from the modulator integrated semiconductor laser device 1 is incident on the optical fiber 9.

The operation of the conventional semiconductor laser device will be described below. In FIG. 11, the semiconductor laser unit 2
When a direct current is supplied to the electrode 5a, continuous light is emitted from the semiconductor laser unit 2 and is incident on the electroabsorption type semiconductor optical modulator unit 3 by the optical waveguide 4. On the other hand, in the electroabsorption type semiconductor optical modulator section 3, the absorption of this laser light changes according to the voltage applied to the electrode 5b. The laser light emitted from the emission end face of the part 3 is subjected to intensity modulation corresponding to the signal voltage, and the modulated laser light is incident on the optical fiber 9 (arrow A in the figure). Become.

Further, in the modulator integrated semiconductor laser device 1, since the wavelength of the laser light oscillated by the semiconductor laser unit 2 changes depending on the temperature, the modulator integrated semiconductor laser device 1 of the prior art is thermoelectrically cooled. An element 7 and a thermistor thermometer (not shown) are provided to keep the temperature of the modulator integrated semiconductor laser element 1 constant.
Stabilization against changes in ambient temperature is achieved.

[0005]

However, the conventional semiconductor laser device shown in FIG. 11 has the following problems. That is, the transmission characteristics of the modulator-integrated semiconductor laser device 1 change according to the difference between the oscillation peak wavelength of the semiconductor laser unit 2 and the absorption peak wavelength of the electroabsorption type semiconductor optical modulator unit 3, that is, the amount of detuning. In general, when the amount of detuning is small, the α parameter which is an index of the magnitude of the wavelength chirp becomes small, the dispersion tolerance against the positive dispersion of the optical fiber 9 becomes large, and even after long-distance transmission, good It has characteristics such that transmission characteristics can be obtained. On the other hand, the oscillation peak wavelength of the semiconductor laser unit 2 and the absorption peak wavelength of the electroabsorption type semiconductor optical modulator unit 3 each have the property of changing with temperature, and their temperature coefficients are also different. When the temperature of the modulator integrated semiconductor laser device 1 changes, the oscillation peak wavelength and the absorption peak wavelength change, the amount of detuning changes, and the transmission characteristics of the modulator integrated semiconductor laser device 1 also change.

As described above, in the conventional semiconductor laser device of FIG. 11, the modulator integrated semiconductor laser device 1 is mounted on one thermoelectric cooling device 7, and the semiconductor laser unit 2 and the electroabsorption type semiconductor optical modulator are provided. Since the temperature of the unit 3 is always maintained at the same temperature, the temperature of each unit cannot be set independently. As a result, it is very difficult to satisfy the desired oscillation wavelength and the desired detuning amount at the same time. Yes,
For example, when giving priority to the oscillation wavelength, there is a problem that the amount of detuning cannot be set to a desired value and good transmission characteristics cannot be obtained. Particularly, in recent long-distance large-capacity optical fiber communication systems, strict wavelength adjustment of a laser light source corresponding to a wavelength multiplexing method and improvement of transmission characteristics corresponding to a long distance are one of the most important issues. Technology development that balances these has been awaited.

In the conventional semiconductor laser device shown in FIG. 11, the semiconductor laser unit 2 and the electroabsorption type semiconductor optical modulator unit 3 are monolithically integrated in the modulator integrated semiconductor laser device 1. The electrode 5a of the semiconductor laser unit 2 and the electrode 5b of the electroabsorption type semiconductor optical modulator unit 3 approach each other, and as a result, the distance between the power supply lines of the semiconductor laser unit 2 and the electroabsorption type semiconductor optical modulator unit 3 becomes narrow. As a result, electrical coupling occurs between the power supply lines, the transmission characteristics are degraded by the wavelength chirp, or the characteristics change due to leakage of the modulation signal of the electroabsorption type semiconductor optical modulator unit 3 into the semiconductor laser unit 2. There were also problems.

The present invention has been made to solve the above-mentioned disadvantages of the conventional semiconductor laser device.
A first object of the present invention is to provide a semiconductor laser device and an electro-absorption type semiconductor optical modulator device that can independently adjust and optimize characteristics such as an oscillation peak wavelength and an absorption peak wavelength. An object of the present invention is to obtain a semiconductor laser device excellent in transmission characteristics and suitable for a long-distance large-capacity optical fiber communication system.

A second object of the present invention is to suppress or separate electrical coupling between a semiconductor laser device and an electroabsorption type semiconductor optical modulator device to thereby improve transmission characteristics due to leakage current and leakage electric field. It is an object to obtain a semiconductor laser device with little deterioration.

A third object of the present invention is to provide a laser by providing a means for increasing the optical coupling efficiency between an optically separated semiconductor laser device and an electroabsorption type semiconductor optical modulator device. It is an object of the present invention to provide a semiconductor laser device capable of increasing the light output and improving the light S / N ratio.

A fourth object of the present invention is to reduce the return light from the electro-absorption type semiconductor optical modulator device or the optical fiber, thereby achieving excellent light output and oscillation wavelength stability.
It is another object of the present invention to provide a semiconductor laser device in which transmission characteristics are less deteriorated due to a change in oscillation conditions due to return light.

[0012]

In order to achieve the above object, a semiconductor laser device according to the present invention modulates a laser beam emitted from the semiconductor laser device and a laser beam emitted from the semiconductor laser device. An electroabsorption type semiconductor optical modulator device, and temperature control means capable of independently controlling the temperatures of the semiconductor laser device and the electroabsorption type semiconductor optical modulator device.

Further, in the semiconductor laser device according to the present invention, the temperature control means is constituted by a cooling means and electric heaters provided respectively in the semiconductor laser element and the electroabsorption type semiconductor optical modulator element. Things.

Further, in the semiconductor laser device according to the present invention, the semiconductor laser device, the electroabsorption type semiconductor optical modulator device, and the temperature control means are housed in the same case.

Further, in the semiconductor laser device according to the present invention, the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are housed in a case, and the cooling means is arranged outside the case. The element and the cooling means, and the electroabsorption type semiconductor optical modulator element and the cooling means are thermally connected by a heat transfer means.

Further, in the semiconductor laser device according to the present invention, the temperature control means may detect the laser light emitted from the electroabsorption type semiconductor optical modulator element based on information from modulated light detection means. The semiconductor laser device and the electroabsorption type semiconductor optical modulator device are configured to control the temperature.

Further, the semiconductor laser device according to the present invention is such that the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are integrally integrated.

Further, in the semiconductor laser device according to the present invention, the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are arranged separately.

Further, in the semiconductor laser device according to the present invention, one or a plurality of coupling optical systems are arranged between the semiconductor laser device and the electroabsorption type semiconductor optical modulator device.

Further, in the semiconductor laser device according to the present invention, the coupling optical system is provided with an optical coating that exhibits low reflection near the oscillation center wavelength of the semiconductor laser element.

Further, in the semiconductor laser device according to the present invention, a spherical fiber is used for the coupling optical system.

Further, in the semiconductor laser device according to the present invention, an optical isolator is arranged between the semiconductor laser device and the electroabsorption type semiconductor optical modulator device.

Further, a semiconductor laser device according to the present invention includes a semiconductor laser device for emitting a laser beam, and a semiconductor laser device for modulating the laser beam emitted from the semiconductor laser device. In the laser device, an electric power supply line for supplying electric power to the semiconductor laser element is provided on a side opposite to an emission side of the semiconductor laser element, and an electric absorption type for supplying a modulation signal to the electric absorption type semiconductor optical modulator element. The semiconductor optical modulator element-side power supply line is arranged on the emission side of the electroabsorption type semiconductor optical modulation element.

Further, a semiconductor laser device according to the present invention includes a semiconductor laser device for emitting laser light, an electroabsorption type semiconductor optical modulator device for modulating laser light emitted from the semiconductor laser device, and a semiconductor laser device. A semiconductor laser device having a temperature control means capable of independently controlling the temperature of the device and the temperature of the electroabsorption type semiconductor optical modulator device. An electro-absorption type semiconductor optical modulator element-side power supply line for supplying a modulation signal to the electro-absorption type semiconductor optical modulator element is disposed on the output side of the electro-absorption type semiconductor optical modulation element. It was done.

Also, in the semiconductor laser device according to the present invention, the semiconductor laser device-side bonding wire for connecting the semiconductor laser device-side power supply line to the semiconductor laser device and a connection portion between the semiconductor laser device electrode and the semiconductor laser device electrode are connected to the semiconductor laser device. An electroabsorption type semiconductor optical modulator element-side bonding wire for connecting the electroabsorption type semiconductor optical modulator element side power supply line and the electroabsorption type semiconductor optical modulator element to the side opposite to the emission side of the laser element; The connection portion between the electrode of the electroabsorption type semiconductor light modulation element and the electrode is arranged on the emission side of the electroabsorption type semiconductor light modulation element.

Further, in the semiconductor laser device according to the present invention, a microstrip line, a suspended line, a slot line, a coplanar line, or the like may be provided on the semiconductor laser element side power supply line or the electroabsorption type semiconductor optical modulator element side power supply line. Alternatively, one of the fin lines is used.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a sectional view illustrating a configuration of a semiconductor laser device according to a first embodiment of the present invention. In FIG. 1, reference numeral 2 denotes a semiconductor laser element, which includes an electrode 5a, an optical waveguide layer (active layer) 4a, and a ground electrode 6a, and a thermoelectric cooling element 7a is fixed below the element as temperature control means. Reference numeral 3 denotes an electroabsorption type semiconductor optical modulator element, which includes an electrode 5b, an optical waveguide layer (absorption layer) 4b, and a ground electrode 6b, and is mounted on a thermoelectric cooling element 7b as a temperature control means. In the first embodiment, the semiconductor laser device 2
And the electroabsorption type semiconductor optical modulator element 3 are physically and electrically separated, housed in a case 8 together with the thermoelectric cooling elements 7a and 7b, and emit laser light from the electroabsorption type semiconductor optical modulator element 3. An optical fiber 9 is installed through the case 8 on the side end face. Temperature sensors 10a and 10b are mounted on the thermoelectric cooling elements 7a and 7b, respectively, as temperature detecting means. The cooling amounts of the thermoelectric cooling elements 7a and 7b are determined based on the outputs from the temperature sensors 10a and 10b. , The temperature of the semiconductor laser element 2 and the temperature of the electroabsorption type semiconductor optical modulator element 3 can be controlled independently of each other.

The operation of the first embodiment will be described below. In FIG. 1, the electrode 5a of the semiconductor laser device 2
When a direct current is supplied to the semiconductor laser device 2, continuous light is emitted from the optical waveguide layer (active layer) 4a of the semiconductor laser device 2 (arrow B in the drawing), and the optical waveguide layer (absorption layer) 4b of the electroabsorption type semiconductor optical modulator device 3 Is incident on. On the other hand, in the electroabsorption type semiconductor optical modulator element 3, the absorption of this laser light changes in accordance with the voltage applied to the electrode 5b. Is electrode 5
After intensity modulation corresponding to the signal voltage applied to b, the light is incident on the optical fiber 9 from the output end face (arrow A in the figure).

During this time, the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 are respectively provided with thermoelectric cooling elements 7a and 7b and a temperature sensor 10 provided below.
The temperature is independently controlled by a and 10b to stabilize the characteristics with respect to the change of the ambient temperature, and the temperature of the semiconductor laser device 2 and the temperature of the electroabsorption type semiconductor optical modulator device 3 are independently set, thereby making the semiconductor laser device The oscillation peak wavelength of the laser beam emitted from the semiconductor laser device 2 and the absorption peak wavelength of the laser beam absorbed by the electroabsorption type semiconductor optical modulator element 3 are separately adjusted to transmit the wavelength of the laser beam emitted from the semiconductor laser device and the transmission. The characteristics are controlled simultaneously.

As described above, according to the first embodiment, the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 are separately provided on the thermoelectric cooling elements 7a and 7b, each of which can independently control the temperature. By adjusting the temperature of the semiconductor laser device 2 and the temperature of the electroabsorption type semiconductor optical modulator device 3 to desired temperatures respectively, the oscillation peak wavelength of the semiconductor laser device 2 is adjusted to a desired wavelength, Absorption wavelength of the semiconductor optical modulator element 3 can be adjusted so that the transmission characteristics are best;
A semiconductor laser device having wavelength controllability and good transmission characteristics can be obtained.

Further, since the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 are electrically separated, the modulation signal of the electroabsorption type semiconductor optical modulator element 3 leaks out to the semiconductor laser element 2. The conventional problem that the transmission characteristics are deteriorated is solved, and the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are separated by the thermoelectric cooling devices 7a and 7b because they are physically (thermally) separated. The temperature of the semiconductor laser device can be controlled more precisely, and the wavelength and the transmission characteristics can be more accurately adjusted.

Further, since the semiconductor laser element 2, the electroabsorption type semiconductor optical modulator element 3 and the thermoelectric cooling elements 7a and 7b as temperature control means are housed in the same case 8, the semiconductor laser element 2 and the electroabsorption type semiconductor The optical modulator element 3 and the thermoelectric cooling elements 7a and 7b are protected, and the optical axes of the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 which are optically separated from each other due to impact or the like may be displaced. Thus, the reliability of the semiconductor laser device is improved, and the handling and workability are also improved.

Embodiment 2 FIG. FIG. 2 is a sectional view showing a configuration of a semiconductor laser device according to a second embodiment of the present invention. In the second embodiment, the semiconductor laser device 2
Although the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator 3 are integrated as a modulator integrated semiconductor laser device 1 as in the conventional example of FIG. The device element 3 is provided with separate temperature control means 7a and 7b, respectively, so that the temperature can be controlled independently.

Thus, according to the second embodiment,
Just like the first embodiment, the oscillation peak wavelength of the semiconductor laser device 2 and the absorption peak wavelength of the electroabsorption type semiconductor optical modulator device 3 can be adjusted, and the wavelength controllability and good transmission characteristics can be obtained. A semiconductor laser device can be obtained. According to the second embodiment, since the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are integrated, the optical axis alignment of the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 is achieved. Processing becomes unnecessary
Since the assembling is facilitated and the laser light is not lost at the entrance and exit end faces of each element, there is also an effect that a highly efficient semiconductor laser device can be obtained.

Embodiment 3 FIG. FIG. 3 shows, as a third embodiment of the present invention, an example in which the temperature control means is composed of a cooling means and a heating means. As shown in the cross-sectional view of FIG. 3, in the third embodiment, electric heaters 11a, 11a, 1b, and 1d are formed by depositing resistors under the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, respectively.
1b is provided as a heating means, and a lower portion thereof is provided with a single thermoelectric cooling element 7 as a cooling means.
The temperature of the semiconductor laser element 2 and the temperature of the electroabsorption type semiconductor optical modulator element 3 are independently controlled by the heat generation amount 1b. Note that the third embodiment
In, the temperature sensors 10a and 10b are directly mounted on the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, respectively, in consideration of the influence of heat generated by the electric heaters 11a and 11b.

As described above, according to the third embodiment, while the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 are cooled by the same thermoelectric cooling element 7, the amount of heat generated by the electric heaters 11a and 11b is controlled. By doing so, the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3
Can be controlled independently of each other, so that exactly the same effect as described above can be obtained. In the semiconductor laser device thus configured, it is not necessary to provide a plurality of thermoelectric cooling elements 7, so that the configuration of the temperature control means is reduced. It also has the effect of being simple and easy to manufacture. In addition, electric heaters 11a, 11
b is advantageous in that a semiconductor laser device capable of more precise temperature control and capable of following a rapid change in ambient temperature can be obtained because control is easier and responsiveness is higher than that of the thermoelectric cooling element 7. There is. Further, the temperature sensor 10
a and 10b were directly attached to the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, respectively.
There is an effect that a more accurate temperature can be measured.

Embodiment 4 FIG. FIG. 4 shows a fourth embodiment according to the present invention in which a thermoelectric cooling element 7 which is a cooling means in the third embodiment is disposed outside case 8, and thermoelectric cooling element 7, semiconductor laser element 2, and an electroabsorption semiconductor An example in which the optical modulator element 3 is thermally connected to the optical modulator 3 by heat transfer means 12a and 12b is shown. In FIG. 4, 12a and 12b are:
Heat transfer means made of, for example, a heat conductive material such as aluminum for thermally connecting the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 to the thermoelectric cooling device 7 disposed outside the case 8. And the thermoelectric cooling element 7
The cooling effect of the bottom of the case 8 and the heat transfer means 12a,
The temperature is transmitted to the semiconductor laser element 2 and the electro-absorption type semiconductor optical modulator element 3 via 12b, and the temperature of each element is controlled independently by controlling the electric heaters 10a and 10b. Also in the fourth embodiment, the temperature sensors 10a and 10b are each provided with a semiconductor laser element in order to avoid a temperature difference caused by the heat transfer means 12a and 12b and a temperature measurement error due to a contact thermal resistance at each contact surface. 2 and the electroabsorption type semiconductor optical modulator element 3.

As described above, according to the fourth embodiment, the heat generated due to the cooling by the thermoelectric cooling element 7 is generated in the case 8.
, The cooling load of the thermoelectric cooling element 7 is reduced to increase the efficiency, and the temperatures of the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 in the case 8 are further stabilized. effective. Further, in the semiconductor laser device configured as described above, instead of the thermoelectric cooling element 7, for example, cooling can be performed by a fin or the like provided outside the case 8, and various cooling means and low-temperature sources can be used. There is also an effect that becomes possible.

In the fourth embodiment, an example in which only the thermoelectric cooling element 7 is exposed outside the case 8 has been described.
The entire temperature control means is installed outside the case 8, and the temperature control means is connected to the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 by the heat transfer means 12a and 12b to perform temperature control. Alternatively, the cooling means, the temperature control means, and the heat transfer means 12 may be provided without passing through the bottom surface of the case 8.
a and 12b may be directly connected. Further, as an example in which the bottom surface of the case 8 is used as the heat transfer means 12a and 12b, for example, the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are fixed to the bottom surface inside the case 8, and the thermoelectric cooling device is used. The temperature may be controlled by the electric heaters 10a and 10b provided in the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 while cooling from outside via the bottom surface of the case 8 by the case 7.

In the first to fourth embodiments, when the ambient temperature and operating conditions are relatively stable, the cooling amount of the thermoelectric cooling elements 7a and 7b is set. Since the temperatures of the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are substantially determined, the temperature sensors 10a and 10b can be omitted.

Further, in the first to fourth embodiments, the temperature sensor 1 is used as the temperature detecting means.
The temperature control of the semiconductor laser element 2 and the electro-absorption type semiconductor optical modulator element 3 is performed based on the outputs of the temperature sensors 10a and 10b using the laser sensors 0a and 10b. An oscillation light detecting means (not shown) for detecting the laser light to be emitted and a modulated light detecting means (not shown) for detecting the laser light after passing through the electroabsorption type semiconductor light modulator element 3. The temperature of the semiconductor laser element 2 or the electroabsorption type semiconductor optical modulator element 3 may be detected by monitoring the characteristics of the laser light such as the distribution, and further, a desired wavelength and a desired wavelength may be detected based on these characteristic data. The temperature control may be performed directly so as to obtain the characteristics. In this case, since the temperature and the temperature of each element are controlled by directly detecting the wavelength and the characteristics, the wavelength and the characteristics can be adjusted more precisely, and a semiconductor laser device which is hardly affected by a change in the temperature dependence can be obtained. There is an effect that it can be. If the temperature dependence of the characteristics of the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3 is known, a modulated light detection for detecting the laser beam after passing through the electroabsorption type semiconductor optical modulator element 3 It is also possible to estimate and control the temperatures of the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 based only on information from the means.

Embodiment 5 FIG. FIG. 5 is a sectional view showing a configuration of a semiconductor laser device according to a fifth embodiment of the present invention. In the figure, reference numeral 13 denotes an optical lens arranged on the optical axis between the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3, and the laser light emitted from the semiconductor laser element 2 is condensed by the optical lens 13. The coupling optical system is configured so as to be incident on the electroabsorption type semiconductor optical modulator device 3. Hereinafter, the same or corresponding portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

As described above, according to the fifth embodiment, since the optical lens 13 is arranged between the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, light is emitted from the semiconductor laser device 2. Since the laser light is efficiently coupled to the electroabsorption type semiconductor optical modulator element 3 by the optical lens 13, the light output that can be extracted from the optical fiber 9 increases, and the light S / N ratio increases with the increase in the light output. Thus, a semiconductor laser device having better transmission characteristics can be obtained.

Although the fifth embodiment has shown the case where one optical lens is used as the coupling optical system, it is needless to say that a plurality of optical lenses may be used.

Embodiment 6 FIG. Further, if the end face of the optical lens 13 described in the fifth embodiment is coated with an optical coating that has low reflection in the vicinity of the oscillation center wavelength of the semiconductor laser element 2, the light emitted from the semiconductor laser element 2 can be reduced to a low loss. 13, the light emitted from the semiconductor laser element 2 can be efficiently supplied to the electroabsorption type semiconductor optical modulator element 3 and the optical fiber 9, and the light output that can be extracted from the optical fiber 9 increases. S
Since the / N ratio increases, there is an effect that a semiconductor laser device having good transmission characteristics can be obtained.

Further, the reflected light generated at the end face of the optical lens 13 is reduced by the optical coating, and the return light to the semiconductor laser element 2 is reduced, so that the semiconductor laser element 2 can be oscillated stably, and the light output In addition, the oscillation wavelength is stabilized, and the wavelength chirp due to the change in the oscillation condition due to the return light and the change in the refractive index of the optical waveguide layer (active layer) 4a of the semiconductor laser element 2 is reduced. Obtainable.

Embodiment 7 FIG. FIG. 6 is a sectional view showing a configuration of a semiconductor laser device according to Embodiment 7 of the present invention. In FIG. 6, reference numeral 14 denotes a spherical fiber whose tip is processed into a spherical shape. By disposing this spherical fiber 14 between the semiconductor laser element 2 and the electroabsorption type semiconductor optical modulator element 3, the semiconductor laser element 2 is formed. The light emitted from the optical fiber 9 is efficiently optically coupled to the electroabsorption type semiconductor optical modulator device 3 so that the optical output that can be extracted from the optical fiber 9 is increased. Thus, according to the seventh embodiment, since the coupling optical system composed of the spherical fiber is disposed between the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, the same as in the fifth embodiment, As the optical output increases, the optical S / N ratio can be increased, and a semiconductor laser device having good transmission characteristics can be obtained.

The diameter of the spherical fiber 14 used in the seventh embodiment is smaller than that of the general optical lens 13 shown in the fifth embodiment, so that a compact semiconductor laser device can be obtained. There is also.

Embodiment 8 FIG. In addition, the semiconductor laser device 2 is attached to the end face of the spherical fiber 14 described in the seventh embodiment.
By applying an optical coating having low reflection in the vicinity of the oscillation center wavelength of the optical fiber, the light emitted from the semiconductor laser element 2 can be made to enter and exit the tip fiber 14 with low loss as in the sixth embodiment. 9, the light output that can be extracted from the light source 9 increases, and the light S / N ratio increases, so that a semiconductor laser device having better transmission characteristics can be obtained.

Further, the optical coating reduces reflected light generated at the end face of the spherical fiber 14 and reduces return light to the semiconductor laser element 2, so that the semiconductor laser element 2 can oscillate stably. A semiconductor laser device having excellent transmission characteristics, in which the output and oscillation wavelength are stabilized, and the wavelength chirp associated with a change in oscillation conditions due to return light and a change in the refractive index of the optical waveguide layer (active layer) 4a of the semiconductor laser element 2 is reduced. Can be obtained.

Embodiment 9 FIG. FIG. 7 is a sectional view illustrating a configuration of a semiconductor laser device according to a ninth embodiment of the present invention. In FIG. 7, reference numeral 15 denotes an optical isolator having a characteristic that the transmission loss is small only in the direction from the semiconductor laser device 2 to the electroabsorption type semiconductor optical modulator device 3, and the transmission loss is large in the opposite direction.

As described above, according to the ninth embodiment, since the optical isolator 15 is arranged between the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, the electroabsorption type semiconductor optical modulator device 3 The reflected light generated at the end face of the optical fiber 9 and the end face of the optical fiber 9 can be prevented from re-entering the semiconductor laser element 2, the return light to the semiconductor laser element 2 is reduced, and the semiconductor laser element 2 is oscillated more stably. Therefore, there is an effect that a semiconductor laser device having good stability of optical output and oscillation wavelength can be obtained. Further, since the wavelength chirp due to the change in the oscillation condition due to the return light and the change in the refractive index of the optical waveguide layer (active layer) 4a of the semiconductor laser element 2 is reduced, a semiconductor laser device having excellent transmission characteristics can be obtained.

Embodiment 10 FIG. FIG. 8 is a plan view showing a configuration in which a power supply line is provided in the semiconductor laser device shown in the fifth embodiment as a tenth embodiment according to the present invention. In FIG. 8, reference numeral 16a denotes a semiconductor laser device-side power supply line for supplying a DC current to the semiconductor laser device 2, which has a conductive metallized portion 17a on an upper surface and a semiconductor laser device-side bonding wire 18a at an end thereof. Is electrically connected to the connection portion 19a of the electrode 5a formed on the upper surface of the semiconductor laser device 2. Reference numeral 16b denotes an electro-absorption type semiconductor optical modulator device-side power supply line for supplying a modulation signal to the electro-absorption type semiconductor optical modulator device 3, which has a conductive metallized portion 17b on the upper surface and has an end portion at the end. In addition, it is electrically connected to the connection portion 19b of the electrode 5b formed on the upper surface of the electroabsorption semiconductor optical modulator element 3 by the electroabsorption semiconductor optical modulator element side bonding wire 18b. Further, between the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3, the fifth embodiment is provided.
Similarly to the above, an optical lens 13 is provided, and the laser light emitted from the semiconductor laser element 2 is condensed by the optical lens 13 and is incident on the electroabsorption type semiconductor optical modulator element 3.

As described above, in the tenth embodiment, since the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are separated, the semiconductor laser device side power supply line 16a is Since the distance between the power supply line 16b and the optical modulator element-side power supply line 16b can be widened and interference and electrical coupling between the power supply lines can be reduced, the electric power supply line on the electro-absorption type semiconductor optical modulator element side can be provided. The wavelength chirp caused by the leakage of the modulation signal electric field on the semiconductor laser element-side power supply line 16a on the semiconductor laser element side 16b can be suppressed low, and a semiconductor laser device having excellent transmission characteristics can be obtained.

Embodiment 11 FIG. FIG. 9 shows a connection part 19a of the electrode 5a of the semiconductor laser device 2, a semiconductor laser device-side power supply line 16a, and a semiconductor laser device-side bonding wire 18a according to an eleventh embodiment of the present invention. The electrode 5 of the electroabsorption type semiconductor optical modulator element 3 is provided at the end opposite to the emission end face.
b, an electroabsorption type semiconductor optical modulator element side power supply line 16b, and an electroabsorption type semiconductor optical modulator element side bonding wire 18b are provided at the end of the electroabsorption type semiconductor optical modulator element 3 on the emission end face side. Here is an example. According to the semiconductor laser device shown in the eleventh embodiment, the connection portions 19a and 19b, the power supply lines 16a and 16b, and the bonding wires 18a and 18b are connected to the power supply line 16a.
Since the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are arranged at the ends of the semiconductor laser device 2 and the electro-absorption type semiconductor optical modulator device 3 so as to increase the interval between 16b, interference and electric coupling between power supply lines can be further reduced, and transmission characteristics are more excellent. A semiconductor laser device can be obtained.

In the eleventh embodiment, an example is shown in which the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 are separated from each other.
Also in a semiconductor laser device in which the electro-absorption type semiconductor optical modulator element 3 is integrally integrated, the distance between the semiconductor laser element-side power supply line 16a and the electro-absorption type semiconductor optical modulator element-side power supply line 16b is set wide. By doing
The same effect as in the eleventh embodiment can be obtained. It is clear that this effect does not depend on the presence or absence of the temperature control means 7a, 7b.

Embodiment 12 FIG. FIG. 10 shows a power supply line 16a according to a twelfth embodiment of the present invention.
An example is shown in which the power supply lines 16a and 16b are arranged obliquely with respect to the optical axis of the laser light in order to set a larger interval between 16b. According to the twelfth embodiment, the distance between the power supply lines 16a and 16b can be further increased,
A semiconductor laser device having more excellent transmission characteristics can be obtained.

In the eleventh and twelfth embodiments, the examples in which the connection portions 19a and 19b are provided at the ends of the semiconductor laser device 2 and the electroabsorption type semiconductor optical modulator device 3 have been described. Even when the portions 19a and 19b are formed in the central portion, arranging the power supply lines 16a and 16b on the end side has an effect of preventing leakage of an electric field between the power supply lines 16a and 16b and improving transmission characteristics. There is. In the twelfth embodiment, the power supply line 16
Although a and 16b are arranged obliquely to the optical axis, they may be installed parallel to the optical axis, or a part of the L-shaped feed lines 16a and 16b may be parallel to the optical axis. And the distance between the power supply lines 16a and 16b may be increased.

Furthermore, if the microstrip line, suspended line, slot line, coplanar line, or fin line is used as the feed lines 16a and 16b shown in the tenth to twelfth embodiments, Transmission line has a strong confinement for high frequency signals, so that the wavelength chirp due to electric field leakage can be further suppressed,
Further, since the influence of inductance is very small as compared with the case where a long bonding wire is used, a semiconductor laser device having more excellent transmission characteristics and capable of high-speed response can be obtained.

[0060]

Since the present invention is configured as described above, it has the following effects.

Since temperature control means for independently controlling the temperature of the semiconductor laser device and the temperature of the electroabsorption type semiconductor optical modulator device for modulating the laser light emitted from the semiconductor laser device are provided, Since the oscillation peak wavelength can be adjusted to a desired wavelength, and the absorption peak wavelength of the electroabsorption type semiconductor optical modulator element can also be adjusted so that transmission characteristics and the like are the best,
There is an effect that a semiconductor laser device excellent in wavelength controllability and transmission characteristics can be obtained.

Further, the temperature control means may include a cooling means,
Since the semiconductor laser device and the electric absorption type semiconductor optical modulator device are configured by electric heaters provided respectively, the temperature control is easy, the responsiveness is high, and the temperature control can be performed more precisely. There is an effect that a semiconductor laser device that can follow a sudden change in temperature can be obtained.

Since the semiconductor laser device, the electroabsorption type semiconductor optical modulator device, and the temperature control means are housed in the same case, the semiconductor laser device and the electroabsorption type semiconductor optical modulator device And the temperature control means is protected, and the optical axes of the semiconductor laser element and the electroabsorption type semiconductor optical modulator element, which are optically separated from each other due to an impact or the like, are less likely to be shifted. This has the effect of improving reliability and improving handling and workability.

Further, the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are housed in a case, and the cooling means is arranged outside the case. Since the semiconductor light modulator element and the cooling means are thermally connected by the heat transfer means, the heat generated in the cooling means is radiated out of the case, so that the efficiency becomes high and the inside of the case becomes high. This has the effect of further stabilizing the temperatures of the stored semiconductor laser device and the electroabsorption type semiconductor optical modulator device. There is also an effect that various cooling means such as fins and a low-temperature source can be used.

Further, the semiconductor laser device and the electroabsorption semiconductor device are controlled by the temperature control device based on information from a modulated light detection device for detecting a laser beam emitted from the electroabsorption semiconductor light modulator device. Since the configuration is such that the temperature of the optical modulator element is controlled, the wavelength and transmission characteristics can be adjusted more precisely, and a semiconductor laser device that is less affected by changes in the temperature dependence can be obtained.

Further, since the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are integrated, the optical axis alignment of the semiconductor laser device and the electroabsorption type semiconductor optical modulator device becomes unnecessary. Processing and assembly of the device are facilitated, and there is no loss of laser light at the entrance and exit end faces of each element, so that a highly efficient semiconductor laser device can be obtained.

Further, since the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are arranged separately, the semiconductor laser device and the electroabsorption type semiconductor optical modulator device are electrically separated from each other, The conventional problem that the modulation signal of the absorption type semiconductor optical modulator element leaks into the semiconductor laser element to deteriorate the transmission characteristics is solved, and the semiconductor laser element is separated from the electric field because the semiconductor laser element is thermally separated. There is an effect that a semiconductor laser device that can more precisely control the temperature of the absorption type semiconductor optical modulator element and can further adjust the wavelength and the transmission characteristics with higher accuracy can be obtained. In addition, since the semiconductor laser element and the electroabsorption type semiconductor optical modulator element are separated from each other, it is possible to increase an interval between power supply lines for supplying power to the semiconductor laser element and the electroabsorption type semiconductor optical modulator element. As a result, interference and electrical coupling between power supply lines can be reduced, so that the wavelength chirp can be suppressed low, and a semiconductor laser device having excellent transmission characteristics can be obtained.

Further, since one or a plurality of coupling optical systems are arranged between the semiconductor laser device and the electro-absorption type semiconductor optical modulator device, the light emitted from the semiconductor laser device is transmitted to the electro-absorption type semiconductor optical modulation device. Since the light can be efficiently incident on the incident end face of the device element, the light output that can be extracted from the optical fiber increases, and the optical S / N ratio increases, a semiconductor laser device having good transmission characteristics can be obtained.

Also, since the coupling optical system is provided with an optical coating that has low reflection near the oscillation center wavelength of the semiconductor laser element, the return light to the semiconductor laser element caused by the reflection in the coupling optical system is small. A semiconductor laser having excellent transmission characteristics, which can stabilize the optical output and the oscillation wavelength of the semiconductor laser element, and can suppress the oscillation condition due to the return light and the wavelength chirp associated with the change in the refractive index of the active layer of the semiconductor laser element. There is an effect that a laser device can be obtained.

Further, since a spherical fiber is used for the coupling optical system, a small and compact semiconductor laser device can be obtained.

Further, since an optical isolator is arranged between the semiconductor laser device and the electroabsorption type semiconductor optical modulator device, reflected light generated at the incident end surface of the electroabsorption type semiconductor optical modulator device and the end surface of the optical fiber can be obtained. It is possible to suppress the reflected light generated in the semiconductor laser element from re-entering the semiconductor laser element and to reduce the return light to the semiconductor laser element, so that the optical output and oscillation wavelength of the semiconductor laser element can be stabilized and the return light It is possible to suppress wavelength chirp caused by a change in the oscillation conditions and the refractive index of the active layer of the semiconductor laser element, and to obtain a semiconductor laser device having excellent transmission characteristics.

Further, a power supply line on the semiconductor laser device side for supplying power to the semiconductor laser device is provided on the side opposite to the emission side of the semiconductor laser device, and an electric field for supplying a modulation signal to the electroabsorption type semiconductor optical modulator device. Type semiconductor optical modulator element-side power supply line is arranged on the emission side of the electroabsorption type semiconductor optical modulation element. Therefore, the distance between the semiconductor laser element side power supply line and the electroabsorption type semiconductor optical modulator element side power supply line is wide. Therefore, the interference and the electric coupling between the power supply lines can be reduced, so that the wavelength chirp can be suppressed low, and a semiconductor laser device having excellent transmission characteristics can be obtained.

Further, the connecting portion between the semiconductor laser device-side bonding wire connecting the semiconductor laser device-side power supply line and the semiconductor laser device and the electrode of the semiconductor laser device is located on the side opposite to the emission side of the semiconductor laser device. ,
Further, an electric absorption type semiconductor optical modulator element-side bonding wire for connecting the electroabsorption type semiconductor optical modulator element side power supply line and the electroabsorption type semiconductor optical modulator element, and an electrode of the electroabsorption type semiconductor optical modulation element. Is arranged on the emission side of the electroabsorption type semiconductor optical modulation element, so that the distance between the power supply lines can be widened, and interference and electrical coupling between the power supply lines can be reduced. Chirp can be suppressed low, and a semiconductor laser device having excellent transmission characteristics can be obtained.

Further, since any one of a microstrip line, a suspended line, a slot line, a coplanar line, and a fin line is used as the power supply line, the wavelength chirp due to electric field leakage can be further reduced. Since the influence of inductance is very small as compared with the case where a long bonding wire is used, there is an effect that a semiconductor laser device having more excellent transmission characteristics and capable of high-speed response can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a configuration of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a sectional view illustrating a configuration of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 3 is a sectional view illustrating a configuration of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 4 is a sectional view illustrating a configuration of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view illustrating a configuration of a semiconductor laser device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view illustrating a configuration of a semiconductor laser device according to a seventh embodiment of the present invention.

FIG. 7 is a sectional view illustrating a configuration of a semiconductor laser device according to a ninth embodiment of the present invention.

FIG. 8 is a plan view illustrating a configuration of a semiconductor laser device according to a tenth embodiment of the present invention.

FIG. 9 is a plan view illustrating a configuration of a semiconductor laser device according to an eleventh embodiment of the present invention.

FIG. 10 is a plan view illustrating a configuration of a semiconductor laser device according to a twelfth embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a configuration of a conventional semiconductor laser device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Modulator integrated semiconductor laser element 2 Semiconductor laser element (semiconductor laser part) 3 Electroabsorption type semiconductor optical modulator element (electric absorption type semiconductor optical modulator part) 4 Optical waveguide layer 4a Optical waveguide layer of semiconductor laser element (active) Layer) 4b Optical waveguide layer (absorption layer) of electroabsorption type semiconductor optical modulator element 5a Electrode of semiconductor laser element (semiconductor laser section) 5b Electrode absorption type semiconductor optical modulator element (electroabsorption type semiconductor optical modulator section) Electrode 6, 6a, 6b Ground electrode 7, 7a, 7b Thermoelectric cooling element (temperature control means, cooling means) 8 Case 9 Optical fiber 10a, 10b Temperature sensor (temperature detection means) 11a, 11b Electric heater (heating means) 12a, 12b Heat transfer means 13 Optical lens (coupling optical system) 14 Spherical fiber (coupling optical system) 15 Optical isolator 16a Semiconductor laser device side Power supply line 16b Electric power absorption type semiconductor optical modulator device side power supply line 17a Metallized portion 17b Metallized portion 18a Semiconductor laser device side bonding wire 18b Electroabsorption type semiconductor optical modulator device side bonding wire 19a Connection portion 19b Connection portion

Claims (15)

[Claims] 1. A semiconductor laser device for emitting a laser beam, an electroabsorption semiconductor optical modulator device for modulating a laser beam emitted from the semiconductor laser device, and the semiconductor laser device and the electroabsorption semiconductor light modulator And a temperature control means capable of independently controlling the temperatures of the device elements. 2. The apparatus according to claim 1, wherein said temperature control means comprises cooling means, and electric heaters provided in each of said semiconductor laser device and said electroabsorption semiconductor optical modulator device. 13. The semiconductor laser device according to claim 1. 3. The semiconductor laser device according to claim 1, wherein the semiconductor laser device, the electroabsorption type semiconductor optical modulator device, and the temperature control means are housed in a same case. Semiconductor laser device. 4. The semiconductor laser device and the electro-absorption type semiconductor optical modulator device are housed in a case, and the cooling means is arranged outside the case. 3. The semiconductor laser device according to claim 2, wherein the semiconductor light modulator element and the cooling unit are thermally connected by a heat transfer unit. 5. The semiconductor laser device and the electro-absorption semiconductor based on information from a modulated light detector that detects laser light emitted from the electro-absorption semiconductor optical modulator device. 5. The semiconductor laser device according to claim 1, wherein a temperature of the optical modulator element is controlled. 6. The semiconductor laser device according to claim 1, wherein said semiconductor laser device and said electroabsorption type semiconductor optical modulator device are integrally integrated. 7. The semiconductor laser device according to claim 1, wherein said semiconductor laser device and said electroabsorption type semiconductor optical modulator device are arranged separately. 8. The semiconductor laser device according to claim 7, wherein one or a plurality of coupling optical systems are arranged between said semiconductor laser device and said electroabsorption type semiconductor optical modulator device. 9. The semiconductor laser device according to claim 8, wherein the coupling optical system is provided with an optical coating that has low reflection near an oscillation center wavelength of the semiconductor laser element. 10. The semiconductor laser device according to claim 8, wherein a spherical fiber is used for the coupling optical system. 11. The semiconductor laser device according to claim 7, wherein an optical isolator is arranged between said semiconductor laser device and said electroabsorption type semiconductor optical modulator device. 12. A semiconductor laser device comprising: a semiconductor laser device for emitting a laser beam; and an electroabsorption type semiconductor optical modulator device for modulating the laser beam emitted from the semiconductor laser device. The power supply line on the side of the semiconductor laser element for supplying power is on the side opposite to the emission side of the semiconductor laser element, and the power supply line on the side of the semiconductor laser modulator for supplying a modulation signal to the semiconductor light modulator element of the electroabsorption type. A semiconductor laser device arranged on the emission side of the electroabsorption type semiconductor light modulation element. 13. A semiconductor laser device-side power supply line for supplying power to said semiconductor laser device, on the side opposite to the emission side of said semiconductor laser device, and for electric field absorption for supplying a modulation signal to said electroabsorption type semiconductor optical modulator device. 12. The semiconductor laser device according to claim 1, wherein a power supply line on the element type semiconductor optical modulator element side is arranged on an emission side of the electroabsorption type semiconductor optical modulator element. 14. A connection portion between a semiconductor laser device-side bonding wire connecting the semiconductor laser device-side power supply line and the semiconductor laser device and an electrode of the semiconductor laser device, on a side opposite to an emission side of the semiconductor laser device. An electroabsorption type semiconductor optical modulator element-side bonding wire connecting the electroabsorption type semiconductor optical modulator element side power supply line and the electroabsorption type semiconductor optical modulator element; and an electrode of the electroabsorption type semiconductor optical modulation element. 14. The semiconductor laser device according to claim 12, wherein a connection portion between the semiconductor laser device and the semiconductor laser device is disposed on an emission side of the electro-absorption type semiconductor light modulation element. 15. The power supply line on the semiconductor laser device side,
2. The method according to claim 1, wherein any one of a microstrip line, a suspended line, a slot line, a coplanar line, and a fin line is used as the power supply line on the electro-absorption type semiconductor optical modulator element side.
The semiconductor laser device according to claim 2.