JP2003174223A - Semiconductor laser, semiconductor laser module and method for controlling semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser which has a high wavelength stability and prevents a kink from occurring. <P>SOLUTION: An optical amplifier integrated excitation light source is realized by forming a semiconductor laser element for outputting a plurality of laser beams of longitudinal oscillation modes containing diffraction gratings, and an optical amplifier for amplifying the laser beam generated from the laser element to output the beam to the exterior on an n-type InP substrate 1. Thus, the injected current of the laser element is fixed to fix the oscillation wavelength, and the injection current of the amplifier is changed to change the optical output of the laser element. Accordingly, a desired optical output operation can be realized without bringing about an unstable operation such as the kink or the like. <P>COPYRIGHT: (C)2003,JPO

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, a semiconductor laser module and a semiconductor laser control method having a semiconductor laser element that outputs a plurality of oscillation longitudinal mode laser lights, and more particularly to an optical amplifier or an optical attenuator. The present invention relates to a semiconductor laser device, a semiconductor laser module, and a semiconductor laser control method, which are integrated on the same substrate.

[0002]

2. Description of the Related Art In recent years, due to the rapid spread of the Internet and the rapid increase in intra-company LAN connections, not only the number of communication calls has increased, but also the volume of transmitted content data has increased and data traffic Increase is a problem. Therefore, in order to prevent deterioration of communication performance due to this problem, wavelength division multiplexing (WDM: Wavelengt
h Division Multiplexing) system has made remarkable progress and is widely used.

In this WDM system, a plurality of optical signals are put on different wavelengths, respectively, so that a single fiber realizes a large capacity transmission up to 100 times that of the conventional one.
In particular, the existing WDM system enables wide-band and long-distance transmission by performing optical amplification using an erbium-doped fiber amplifier (hereinafter, EDFA) or Raman amplifier. Here, the EDFA is a transmission signal having a wavelength of 1550 n when light is transmitted through a special optical fiber doped with an element called erbium with a pumping laser having a wavelength of 1480 nm or 980 nm (for example, refer to Patent Document 1).
It is a centralized optical fiber amplifier that applies the principle that m-band light is amplified in the special fiber. On the other hand, the Raman amplifier is an optical amplifier that can amplify the signal light as it is by using an already installed optical fiber as an amplification medium, and is a distributed optical fiber amplifier using stimulated Raman scattering.

Therefore, in the WDM system, not only the signal light source for generating the optical signal itself, but also the pumping light source used in the above optical fiber amplifier,
It is necessary to realize highly accurate oscillation control and high output operation. Particularly, the signal light source and the excitation light source are realized by semiconductor laser elements, and the signal modulation and the amplification degree can be electrically controlled.

In a semiconductor laser element used as a signal light source, a direct modulation method in which an injection current applied to the semiconductor laser element is modulated with a signal is often used in order to enable high-speed and large-capacity information transmission. However, there is a problem of so-called wavelength chirping, in which the carrier density in the active layer changes as the injection current changes, the refractive index changes, and the oscillation wavelength changes. Therefore, at present, a so-called modulator integrated light source in which a semiconductor laser device and a semiconductor optical modulator are integrated on the same substrate has been developed. In the modulator integrated light source, since the modulation is performed by the semiconductor optical modulator section, the variation of the injection current in the semiconductor laser element section does not occur, so that the problem of wavelength chirping described above is avoided.

[0006]

[Patent Document 1] JP-A-5-145194

[0007]

However, in a semiconductor laser device which includes a diffraction grating used as a pumping light source in a laser resonator and oscillates in a longitudinal multimode with a narrow spectrum, the injection current does not change due to modulation, Since the injection current is large, the current due to the longitudinal mode hop −
There is a problem that bending of the characteristic curve seen in the light output characteristic, so-called kink, is likely to occur.

Further, in an ultra-long-distance WDM system in which the number of relays exceeds 100, the gain deviation in these optical amplifiers is very small regardless of whether or not the structure includes the EDFA, the Raman amplifier, or both. However, there is a problem that deviation increases as the number of relay stages increases, resulting in a narrow gain band.To solve this problem, the pumping light source of each amplifier, that is, the output power of the semiconductor laser device is controlled. Was there. For example, like a Raman amplifier,
When the pumping light source is composed of a plurality of semiconductor laser elements having different oscillation wavelengths, it is necessary to control the output power for each semiconductor laser element corresponding to each wavelength in order to flatten the gain of the amplifier. is there.

However, the control of the output power, that is, the increase / decrease of the injection current, causes the fluctuation of the oscillation wavelength as described above, and there is a problem that the above-mentioned gain deviation cannot be completely eliminated. .

Further, when a semiconductor laser device is used as a pumping light source for a Raman amplifier, a new problem has arisen with the demand for higher output. As described above, the excitation light emitted from the excitation light source enters the optical fiber, but when light having an intensity higher than a certain threshold enters the optical fiber, stimulated Brillouin scattering occurs. Stimulated Brillouin scattering is a nonlinear optical phenomenon in which incident light interacts with an acoustic wave (phonon) to cause scattering (reflection). It is observed as a phenomenon in which light having a frequency lower by about 11 GHz is reflected in the direction opposite to the incident light due to the loss of phonon energy.

In the Raman amplifier, when this stimulated Brillouin scattering occurs, a part of the incident pumping light is reflected backward and does not contribute to Raman gain generation. In addition, this scattered light may generate unintended noise. In other words, the occurrence of stimulated Brillouin scattering hinders stable and reliable optical amplification.

The present invention has been made in view of the above, and the injection current of the semiconductor laser device is fixed by integrating the optical amplifier and the optical attenuator on the same substrate as the semiconductor laser device, and the oscillation wavelength An object of the present invention is to provide a semiconductor laser device, a semiconductor laser module, and a semiconductor laser control method capable of suppressing fluctuation and generation of stimulated Brillouin scattering.

[0013]

In order to achieve the above object, a semiconductor laser device according to a first aspect of the present invention is formed between an emission end face and a reflection end face of laser light and in the vicinity of an active layer. The semiconductor laser element portion that generates laser light of a plurality of oscillation longitudinal modes and the semiconductor substrate on which the semiconductor laser element portion is formed are shared and integrated by the wavelength selection characteristic of the diffraction grating, and the output of the laser light is output. And a semiconductor light adjusting unit for adjusting.

According to the first aspect of the present invention, the semiconductor laser element section generates a plurality of oscillation longitudinal mode laser beams having a predetermined output value such as a threshold value at which stimulated Brillouin scattering occurs, and outputs the laser beams. The power can be adjusted by the semiconductor light adjusting unit integrated on the same semiconductor substrate as the semiconductor laser device unit.

A semiconductor laser device according to a second aspect of the present invention is the semiconductor laser device according to the above-mentioned invention, wherein at least one electrode of an electrode pair for applying a current to the semiconductor laser element portion,
At least one electrode of the electrode pair for applying a current to the semiconductor light adjusting section is electrically separated by a separation groove formed above a coupling boundary between the semiconductor laser element section and the semiconductor light adjusting section. It is characterized by

According to the second aspect of the present invention, an electrode electrically separated by the separation groove is provided between the semiconductor laser device section and the semiconductor light adjusting section integrated on the same semiconductor substrate. Thus, it is possible to control with different applied currents or applied voltages.

According to a third aspect of the present invention, there is provided a semiconductor laser device according to the above-mentioned invention, which has a laminated structure in which the semiconductor light adjusting section is formed of a waveguide having a composition different from at least the active layer of the semiconductor laser element section. It is characterized by being.

According to the third aspect of the present invention, the semiconductor laser element section and the semiconductor light adjusting section can be formed with different crystal growth parameters, so that optimum characteristics are obtained for the semiconductor laser element section and the semiconductor light adjusting section, respectively. be able to.

According to a fourth aspect of the present invention, in the semiconductor laser device according to the above invention, the semiconductor laser element portion has a reflection end face of the laser light as an end face and a high reflection film is provided on the end face. The light adjusting section is characterized in that the emitting end face of the laser light is used as an end face and a low reflection film is provided on the end face.

According to the fourth aspect of the present invention, the two end faces of the semiconductor laminated structure formed by joining the semiconductor laser element portion and the semiconductor light adjusting portion are used as the laser light reflecting surface and the laser light emitting surface, respectively. be able to.

According to a fifth aspect of the present invention, in the semiconductor laser device according to the above invention, the semiconductor light adjusting section has a laminated structure of semiconductor optical amplifiers for amplifying an output of the laser light generated in the semiconductor laser element section. It is characterized by being.

According to the fifth aspect of the present invention, the semiconductor laser element section generates a plurality of oscillation longitudinal mode laser beams having a predetermined output value such as a threshold value at which stimulated Brillouin scattering occurs, and the laser beam outputs. The power can be amplified by the semiconductor light adjusting unit integrated on the same semiconductor substrate as the semiconductor laser device unit.

A semiconductor laser device according to a sixth aspect of the present invention is characterized in that, in the above-mentioned invention, the semiconductor optical amplifier has a laminated structure formed by sharing at least an active layer of the semiconductor laser element portion. There is.

According to the sixth aspect of the present invention, it is possible to share the active layers required for causing the semiconductor laser element section and the semiconductor light adjusting section to function respectively.

According to a seventh aspect of the present invention, in the semiconductor laser device according to the above invention, the semiconductor light adjusting section has a laminated structure of a semiconductor optical attenuator for attenuating an output of the laser light generated in the semiconductor laser element section. It is characterized by being.

According to the seventh aspect of the present invention, the semiconductor laser element section generates a plurality of oscillation longitudinal mode laser beams having a predetermined output value such as a threshold value at which stimulated Brillouin scattering occurs, and the laser beam outputs. The power can be attenuated by the semiconductor light adjusting section integrated on the same semiconductor substrate as the semiconductor laser element section.

According to an eighth aspect of the present invention, in the semiconductor laser device according to the above invention, the semiconductor optical attenuator is provided in a separation groove formed above a coupling boundary between the semiconductor laser element portion and the semiconductor light adjusting portion. It is characterized in that a high resistance layer is laminated.

According to the eighth aspect of the present invention, even when a reverse bias is applied to the semiconductor light adjusting section, the leakage current to the semiconductor laser element section can be cut off.

Further, in a semiconductor laser device according to a ninth aspect of the present invention, in the above invention, the semiconductor optical attenuator has an absorption layer having an energy gap smaller or larger than the oscillation wavelength energy of the semiconductor laser element section. Is characterized by.

According to the invention of claim 9, the light attenuation amount by the absorption layer can be designed to a desired value.

According to a tenth aspect of the present invention, in the semiconductor laser device according to the above invention, the semiconductor laser element section emits laser light of 1200 nm during laser oscillation.
As described above, it is characterized by having a wavelength of 1600 nm or less.

Further, a semiconductor laser device according to an eleventh aspect of the present invention is characterized in that, in the above invention, the cavity length is 800 μm or more and 3200 μm or less.

According to a twelfth aspect of the present invention, in the above-mentioned invention, the semiconductor laser device is characterized in that the diffraction grating length of the diffraction grating of the semiconductor laser element portion is 300 μm or less.

According to a thirteenth aspect of the present invention, in the semiconductor laser device according to the thirteenth aspect, the diffraction grating length of the diffraction grating of the semiconductor laser element portion is (300/130).
It is characterized in that it is not more than 0) times the value.

According to a fourteenth aspect of the present invention, in the above-mentioned invention, the semiconductor laser device is characterized in that the multiplication value of the coupling coefficient of the diffraction grating of the semiconductor laser element portion and the diffraction grating length is 0.3 or less. There is.

A semiconductor laser device according to a fifteenth aspect of the present invention is characterized in that, in the above invention, the diffraction grating of the semiconductor laser element portion has a predetermined period fluctuation in the grating period.

A semiconductor laser device according to a sixteenth aspect of the present invention is characterized in that, in the above invention, the diffraction grating of the semiconductor laser element portion changes the grating period randomly or at a predetermined period.

A semiconductor laser module according to a seventeenth aspect is the semiconductor laser device according to any one of the first to sixteenth aspects, and a light for guiding the laser light emitted from the semiconductor laser device to the outside. A fiber, and an optical coupling lens system for optically coupling the semiconductor laser device and the optical fiber are provided.

According to the invention of claim 17, claim 1
The semiconductor laser device according to any one of 1 to 16 can be provided in a package housing.

A semiconductor laser control method according to an eighteenth aspect of the present invention is the semiconductor laser control method for controlling the output of laser light output from the semiconductor laser device according to any one of the first to sixteenth aspects. The method is characterized by including a step of fixing a current applied to the semiconductor laser device section and a step of adjusting a current or a voltage applied to the semiconductor light adjusting section.

According to the eighteenth aspect of the present invention, the output power of the finally output laser light is adjusted and output by the semiconductor light adjusting unit while the injection current of the semiconductor laser element unit is not changed. You can

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a semiconductor laser device, a semiconductor laser module and a semiconductor laser control method according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to this embodiment.

(First Embodiment) First, a semiconductor laser device and a semiconductor laser control method according to the first embodiment will be described. The semiconductor laser device according to the first embodiment integrates a semiconductor laser element section and an optical amplifier section on the same semiconductor substrate to control the output power by the optical amplifier section and to reduce the injection current of the semiconductor laser element section. It is characterized by being fixed. In addition, here, as the optical amplifier unit,
An SOA (Semiconductor Optical Amplifier) is taken as an example.

FIG. 1 is a longitudinal sectional view of the semiconductor laser device according to the first embodiment in the longitudinal direction. Furthermore, FIG.
FIG. 2 is a sectional view of the semiconductor laser device shown in FIG. 1 taken along the line AA. In FIG. 1, the semiconductor laser device according to the first embodiment is formed on the (100) plane of an n-InP substrate 1 sequentially.
n-InP buffer layer 2 that also serves as a buffer layer and a lower cladding layer made of n-InP, GRIN- having compressive strain
SCH-MQW (Graded Index-Separate Confinement H
eterostructure Multi Quantum Well) Active layer 3, p-
The InP spacer layer 4 and the p-InP clad layer 6 are laminated and configured.

On the p-InP clad layer 6, p-
After the InGaAsP cap layer and the p-side electrode are sequentially stacked, the isolation groove 21 is formed as shown in the drawing, so that p
A pair of InGaAsP cap layer 7 and p-side electrode 10,
The p-InGaAsP cap layer 17 and the pair of p-side electrodes 20 are arranged in a state of being substantially electrically insulated. Also,
An n-side electrode 11 is formed on the back surface of the n-InP substrate 1.

Further, as shown in FIG. 1, a reflectance of 8 is formed on the light reflecting end face which is one end face in the longitudinal direction of the semiconductor laser device.
The reflection film 14 having a high light reflectance of 0% or more is formed, and the light emitting end surface which is the other end surface has an emission side reflection film 15 having a low light reflectance of 2% or less, preferably 1% or less. Is formed. The light generated in the GRIN-SCH-MQW active layer 3 of the optical resonator formed by the reflection film 14 and the diffraction grating 13 is reflected by the reflection film 14 and amplified by the light amplification section, and the emission side reflection film 15 is formed. Is emitted as laser light. As shown in the drawing, the window region 22 is provided so as to be adjacent to the emission end face, and thereby, an effective low reflectance is realized together with the emission side reflection film 15.
The influence of the reflection of light from the emission end face is reduced. Although the window structure is used in the present embodiment, even if the window structure is not used, a structure using a reflection film of 1% or less, more preferably 0.1% in the emitting side reflection film 15, The same effect can be obtained.

Furthermore, the semiconductor laser device shown in FIG.
p-I periodically arranged in the p-InP spacer layer 4
It has a diffraction grating 13 of nGaAsP. In particular, the diffraction grating 13 has a center wavelength of 1.48 μm in the laser light generated in the gain region of the GRIN-SCH-MQW active layer 3.
In order to select the light of (1), a surface (hereinafter referred to as a central dividing section) 29 which divides the above-mentioned separation groove 21 in the direction perpendicular to the paper surface of FIG. It has a film thickness of 20 nm and is formed with a pitch of about 220 nm. It is desirable that the diffraction grating 13 is arranged from a position in contact with the central dividing surface 29, but it is not necessary to arrange the diffraction grating 13 in such a manner that the function of the diffraction grating 13 is exerted, for example, 20 μm to 10 μm.
It may be arranged at a position separated from the central dividing surface 29 within a range of about 0 μm.

In the diffraction grating 13, the multiplication value of the coupling coefficient κ of the diffraction grating and the diffraction grating length Lg is set to 0.3 or less, so that the linearity of the drive current-optical output characteristic is improved and the optical output is improved. The stability of is improved. Further, when the resonator length L is 1300 μm, oscillation occurs in a plurality of oscillation longitudinal modes when the diffraction grating length Lg is about 300 μm or less, so the diffraction grating length Lg is preferably 300 μm or less. By the way, since the oscillation longitudinal mode interval also changes in proportion to the length of the resonator length L, the diffraction grating length Lg has a value proportional to the resonator length L. That is, in order to maintain the relationship of (diffraction grating length Lg) :( resonator length L) = 300: 1300,
The relationship in which a plurality of oscillation longitudinal modes are obtained when the diffraction grating length Lg is 300 μm or less can be expanded as Lg × (1300 (μm) / L) ≦ 300 (μm). That is, the diffraction grating length L
g is set so as to maintain a ratio with the resonator length L, and is set to a value equal to or less than (300/1300) times the resonator length L. Further, the diffraction grating 13 may be formed with a grating period having a predetermined period fluctuation, or having a random or a predetermined period change.

As shown in FIG. 2, the p-InP spacer layer 4 including the upper part of the n-InP buffer layer 2, the GRIN-SCH-MQW active layer 3 and the diffraction grating 13 described above is formed as follows.
The mesa stripe is processed, and both sides of the mesa stripe are filled with a p-InP blocking layer 8 and an n-InP blocking layer 9 formed as current blocking layers.

In particular, in this semiconductor laser device, the reflection film 14 side functions as a semiconductor laser element and the emission side reflection film 15 side functions as an optical amplifier with the separation groove 21 as a boundary. In other words, the laser light generated in the semiconductor laser device portion is GRIN− located below the separation groove 21.
In the SCH-MQW active layer 3, the light continuously enters the optical amplifier unit and is amplified in the optical amplifier unit. Finally, the laser beam amplified by the optical amplifier section is emitted from the emitting side reflection film 1.
It is output to the outside via 5.

The characteristics of the semiconductor laser device section will be described below. When the semiconductor laser device described above is used as a pumping light source for a Raman amplifier, its oscillation wavelength λ ₀
Is 1100 nm to 1550 nm, and the resonator length L is determined by the distance between the reflection film 14 and the emission-side reflection film 15 described above.
Is 800 μm or more and 3200 μm or less. By the way, in general, the mode interval Δλ of the longitudinal mode generated by the resonator of the semiconductor laser device can be expressed by the following equation, where the equivalent refractive index is “n”. That is, Δλ = λ ₀ ² / (2 · n · L). Here, when the oscillation wavelength λ ₀ is 1480 nm and the effective refractive index is 3.5, when the resonator length L is 800 μm, the mode interval Δλ of the longitudinal mode is about 0.39 nm, and the resonator length is 3200 μm. At this time, the mode interval Δλ of the longitudinal mode is about 0.1 nm. That is, the longer the resonator length L, the longer the mode interval Δλ of the longitudinal mode.
Becomes narrower, and the selection condition for oscillating a single longitudinal mode laser beam becomes stricter.

On the other hand, the diffraction grating 13 selects the longitudinal mode according to its Bragg wavelength. FIG. 3 is a graph for explaining the selection wavelength characteristic of the diffraction grating 13, and the selection wavelength characteristic of the diffraction grating 13 is represented as an oscillation wavelength spectrum 30 as illustrated.

In particular, in this semiconductor laser device, as shown in FIG. 3, due to the existence of the diffraction grating 13, a plurality of oscillation longitudinal modes are present within the wavelength selection characteristic represented by the half width Δλh of the oscillation wavelength spectrum 30. Designed to. In the conventional semiconductor laser device, when the resonator length L is 800 μm or more, single longitudinal mode oscillation is difficult, and therefore the semiconductor laser device having such resonator length L is not used, but this semiconductor laser device is not used. Then, by positively setting the cavity length L to 800 μm or more, laser light including a plurality of oscillation longitudinal modes is output within the half-width Δλh of the oscillation wavelength spectrum. In FIG. 3, there are three oscillation longitudinal modes 31 to 33 within the half width Δλh of the oscillation wavelength spectrum.

When a laser beam having a plurality of oscillation longitudinal modes is used, the peak value of the laser output can be suppressed and a high laser output value can be obtained, as compared with the case where a laser beam having a single longitudinal mode is used. . FIG. 4 is an explanatory diagram for explaining each profile of laser light of a single longitudinal mode and laser light of a plurality of oscillation longitudinal modes. For example, the above-mentioned semiconductor laser device portion has the profile shown in FIG. 4B, and a high laser output can be obtained with a low peak value.
On the other hand, FIG. 4A shows a profile of a semiconductor laser device section of single longitudinal mode oscillation when the same laser output is obtained, and has a high peak value.

Here, when the semiconductor laser device according to the first embodiment is used as a pumping light source of a Raman amplifier,
It is preferable to increase the pumping light output power in order to increase the Raman gain, but if the peak value is high, stimulated Brillouin scattering occurs and noise increases. Stimulated Brillouin scattering occurs when the laser output exceeds a threshold Pth at which stimulated Brillouin scattering occurs, as shown in FIG. Therefore, in this semiconductor laser device, in order to obtain the same laser output power as the profile shown in FIG. 4A, as shown in FIG. 4B, a plurality of peak values are suppressed below the threshold value Pth of stimulated Brillouin scattering. The laser light is emitted in the oscillation longitudinal mode of. Thereby, high pumping light output power can be obtained, and as a result, high Raman gain can be obtained.

Further, in FIG. 3, oscillation longitudinal modes 31 to 31 are generated.
The wavelength interval (mode interval) Δλ of 33 is 0.1 nm or more. This is because when this semiconductor laser device is used as a pumping light source for a Raman amplifier, if the mode interval Δλ is 0.1 nm or less, stimulated Brillouin scattering is likely to occur. As a result, the above-mentioned resonator length L is 32 by the above-mentioned equation of the mode interval Δλ.
It is preferable that the thickness is 00 μm or less. From such a viewpoint, the half-width Δλh of the oscillation wavelength spectrum 30
It is desirable that the number of oscillation longitudinal modes included in the above is plural.

Therefore, as described above, in the semiconductor laser device according to the first embodiment, the arrangement position of the diffraction grating 13 and the resonance are arranged so that two or more oscillation longitudinal modes are included in the half width of the oscillation wavelength spectrum. Since the device length L is set, it is possible to stably obtain a high-power laser output without causing stimulated Brillouin scattering.

In the above description of the semiconductor laser device 20, the reflectance of the emitting side reflection film 15 is 2% or less,
The low light reflectance is preferably 1% or less, but conversely, it may be 1% or more. As a result, even if the return light reaches the emitting side of the semiconductor laser device 20, the return light is further reflected by the high reflectance to prevent the return light from entering the semiconductor laser device 20. be able to.

In FIG. 1, the output power of the laser light generated in the semiconductor laser element portion is the current applied between the p-side electrode 10 and the n-side electrode 11, that is, GRIN-S.
It increases in proportion to the injection current into the CH-MQW active layer 3. However, the fluctuation of the heat generation amount of the active layer temperature accompanying the fluctuation of the injection current causes the fluctuation of the oscillation wavelength due to the refractive index change of the diffraction grating. FIG. 5 is a diagram showing the relationship between the injection current and the oscillation wavelength in the semiconductor laser device section.

As shown in FIG. 5, as the injection current increases, the oscillation wavelength shifts to the long wavelength side. In other words, in a Raman amplifier that uses different injection currents, the gain spectrum will change with the injection current, making stable amplification of the transmission signal difficult.
It becomes difficult to realize accurate optical transmission. Therefore, in the semiconductor laser device according to the first embodiment, as shown in FIG. 5, by fixing the injection current applied to the semiconductor laser element portion (injection current I ₁ ), the oscillation wavelength of the generated laser light is Is also fixed (wavelength λ ₁ ).

However, if the injection current of the semiconductor laser element is fixed, the oscillation wavelength can be fixed, but the output power cannot be changed.
Therefore, the injection current of the semiconductor laser device section is set to a low level in advance to reduce the output power of the laser light generated there, and the small output laser light is amplified by the optical amplifier section, whereby the semiconductor laser device It controls the output power of the final laser light output from the device and realizes stable wavelength operation over the output range.

FIG. 6 is a diagram showing the relationship between the injection current and the output power of the semiconductor laser device section for each drive current of the optical amplifier section. As shown in FIG. 6, when the drive current I _s of the optical amplifier section is 0 mA, the relationship between the injection current and the output power according to the characteristics of the semiconductor laser element section is shown as described above. On the other hand, as the drive current I _s of the optical amplifier unit increases, the output power of the final laser light output from the emitting side reflection film 15 increases.

The drive current of the optical amplifier section corresponds to the applied current between the p-side electrode 20 and the n-side electrode 11, and the carriers generated by the applied current are GRIN-SCH-.
The amplifying action is exerted on the laser light passing through the MQW active layer 3.

Therefore, in the semiconductor laser device according to the first embodiment, laser light having a desired output power can be obtained by the operation of the optical amplifier section even if the injection current of the semiconductor laser element section is fixed to be small. This means that it is possible to carry out the wavelength stabilizing operation and prevent the occurrence of kinks due to an increase in injection current.

In particular, in the configuration of the semiconductor laser device shown in FIG. 1, the semiconductor laser element section and the optical amplifier section are smoothly and continuously connected, no excessive connection loss occurs, and the manufacturing process is extremely difficult. You can enjoy many advantages such as being easy.

The semiconductor laser element section and the optical amplifier section may be formed by so-called butt joint bonding, which are formed by different crystal growths. FIG. 7 is a vertical cross-sectional view of the semiconductor laser device according to the first embodiment formed by butt coupling. In FIG. 7, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The semiconductor laser device shown in FIG. 7 is different from that in FIG. 1 in that the optical amplifier section is formed on the n-InP substrate 1 in order, and the n-InP doubles as a buffer layer and a lower cladding layer made of n-InP. Buffer layer 25 and GRIN-SC
The H-MQW active layer 23 and the p-InP clad layer 26 are laminated, and the crystal growth thereof is the n-InP buffer layer 2 and GRIN constituting the semiconductor laser device portion.
This is a point different from the process of forming the -SCH-MQW active layer 3, the p-InP spacer layer 4 and the p-InP cladding layer 6.

In particular, the above-mentioned laminated structure constituting the semiconductor laser element portion is formed with the optimum crystal growth parameter for forming the semiconductor laser element, and the laminated structure constituting the optical amplifier portion also forms the optical amplifier. It is formed with optimum crystal growth parameters.

As described above, according to the semiconductor laser device and the semiconductor laser control method according to the first embodiment, a semiconductor laser element portion for outputting a plurality of oscillation longitudinal mode laser beams is provided on the same semiconductor substrate. , An optical amplifier integrated pumping light source is realized by forming an optical amplifier section that amplifies the laser light generated in the semiconductor laser element section and outputs it to the outside, so that the injection current of the semiconductor laser element section is fixed. Even if it is made smaller, the output power of the emitted laser light can be adjusted by controlling the drive current of the optical amplifier section. That is, the output power of the laser light can be adjusted, the problem of wavelength chirping can be solved by fixing the injection current, and kink can be prevented from occurring due to the low injection current.

(Second Embodiment) Next, a semiconductor laser device and a semiconductor laser control method according to a second embodiment will be described. In the semiconductor laser device according to the second embodiment, the optical amplifier unit of the semiconductor laser device according to the first embodiment is replaced with an optical attenuator unit, and the output power of the laser light generated in the semiconductor laser element unit is set to an arbitrary value. It is characterized in that it is possible to adjust the final output power by attenuating the output. Here, as the optical attenuator section,
An optical attenuator formed of a semiconductor will be taken as an example.

FIG. 8 is a longitudinal sectional view in the longitudinal direction of the semiconductor laser device according to the second embodiment. In addition, in FIG. 8, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In particular, the semiconductor laser element portion shown in FIG. 8 is a portion that constitutes a semiconductor laser element that outputs a plurality of oscillation longitudinal mode laser beams having a diffraction grating.

In FIG. 8, the optical attenuator section is formed on the n-InP substrate 1 shared by the semiconductor laser element section and n-InP.
N-In which also serves as a buffer layer and a lower cladding layer by
The P buffer layer 45, the absorption layer 43, and the p-InP clad layer 46 are formed and configured.

On the p-InP cladding layer 46, the InGaAsP cap layer 17 and the p-side electrode 20 are sequentially stacked on the p-InP cladding layer 46, as described in the first embodiment.
An n-side electrode 11 is formed on the back surface of the P substrate 1. However, the optical attenuator unit operates by a reverse bias that gives a negative potential to the p-side electrode 20.

Therefore, there is a concern that a leakage current may be generated between the p-side electrode 20 and the p-side electrode 10 which constitutes the semiconductor laser element portion. This is due to the semiconductor laser element portion and the optical attenuator portion. Is formed by butt coupling as described above, and a high resistance layer doped with Fe or protons is provided in the blocking region 40 corresponding to the separation groove 21 shown in FIG.

Further, the absorption layer 43 needs to be formed of a semiconductor mixed crystal having an appropriate composition ratio so as to have a band gap that efficiently absorbs the laser light generated in the semiconductor laser element section.

In the semiconductor laser device according to the second embodiment, since the output power needs to be adjusted by attenuation, it is necessary to fix the injection current of the semiconductor laser element portion to a high value.

Next, the point that the semiconductor laser device according to the second embodiment is effective in suppressing the occurrence of stimulated Brillouin scattering will be described. DFB (Dist
A conventional semiconductor laser device with a built-in diffraction grating such as a ributed feedback (distributed feedback type) laser is also used as a light source for Raman amplification, but as described in the section of the conventional technique,
When trying to obtain higher Raman gain, that is, when trying to obtain higher optical output power, the occurrence of stimulated Brillouin scattering becomes a problem. In order to avoid the occurrence of this stimulated Brillouin scattering, it is sufficient to simply reduce the optical output power. Well known methods of reducing optical output power are:
To reduce the drive current of the semiconductor laser module. However, the inventors of the present invention have made it possible to reduce the drive current in order to avoid the occurrence of stimulated Brillouin scattering in comparison with a conventional single mode oscillation type semiconductor laser module such as a semiconductor laser module for excitation with a built-in diffraction grating. However, it is not necessarily the best solution for a multi-mode oscillation type semiconductor laser module.

FIG. 9 is a graph showing the relationship between the driving current and the optical output power together with the threshold value for the occurrence of stimulated Brillouin scattering. In particular, FIG. 9A shows a drive current-optical output power graph (Pw) and a stimulated Brillouin scattering generation threshold graph (Pth) for the single mode oscillation type semiconductor laser module, and FIG. FIG. 15 shows a drive current-optical output power graph (Pw) and a stimulated Brillouin scattering generation threshold graph (Pth) for the multimode oscillation type semiconductor laser module shown in FIGS.

In FIG. 9A, stimulated Brillouin scattering does not occur only when the drive current is less than C1. on the other hand,
In FIG. 9B, as the drive current increases, the threshold value for the stimulated Brillouin scattering increases with the optical output power.

In FIG. 9B, unlike the case of FIG. 9A, even when the optical output power is attenuated by a relatively small amount of attenuation as shown by the arrow, the stimulated Brillouin scattering occurs in a wide drive current range. Occurrence can be avoided. For this reason, the inventors of the present invention have proposed a method of attenuating the emitted laser light for the multimode oscillation type semiconductor laser element portion shown in FIGS. 1 to 4 to avoid the occurrence of stimulated Brillouin scattering. It has been found to be the most effective. In the present embodiment, the above-mentioned optical attenuator unit realizes the optical attenuation.

The conditions under which stimulated Brillouin scattering occurs will be described. FIG. 10 is a schematic diagram showing the structure of a measuring device for detecting the degree of occurrence of stimulated Brillouin scattering. In this measuring device, a multimode oscillation type semiconductor laser device 50a having the characteristics of FIGS. 3 and 4, an optical attenuator 50b, and a reflected light measuring means 53 are arranged on one side through a coupler 51 and the transmission light is on the other side. A fiber 54 and an input light measuring means 55 are arranged. One and the other are connected to each other via a coupler 51, and the transmission optical fiber 54 is connected to the output light measuring means 56.
The transmission optical fiber 54 has a DSF (Dispersion).
Shifted Fiber) is used to transmit optical fiber 54
Has a length of 55 km and a core diameter of 10 μm.

In the measuring apparatus shown in FIG. 10, the input light measuring means 55 receives a light having a certain ratio to the intensity of the laser light output from the optical attenuator 50b, and the reflected light measuring means 53 is for transmission. Light having a certain ratio to the intensity of the light scattered and returned by the optical fiber 54 enters.

Here, when the stimulated Brillouin scattering occurs, the intensity of the light incident on the reflected light measuring means 53 increases. Therefore, the ratio (hereinafter, referred to as “scattering intensity ratio”) between the intensity of light incident on the transmission optical fiber 54 from the semiconductor laser device 50a and the intensity of light scattered and returned by the transmission optical fiber 54. By taking it, it can be determined whether stimulated Brillouin scattering has occurred. Generally, when a semiconductor laser device is used as an excitation light source in optical communication, if the scattering intensity ratio can be suppressed to a value of about −28 dB,
It is considered to be the background level due to Rayleigh scattering, and stimulated Brillouin scattering does not occur, and it is said that there is no problem in using it as an excitation light source.

Even if the scattering intensity ratio has a value of -28 dB or more as measured by the measuring device of FIG. 10, it may be possible to use it as an excitation light source. FIG. 11 is a graph showing the relationship between the attenuation amount and the scattering intensity ratio for six samples of the multimode oscillation type semiconductor laser device having the characteristics of FIGS. 3 and 4. As shown in FIG. 11, it can be seen that although the number of modes of each sample is different from each other, the scattering intensity ratio decreases as the amount of optical attenuation by the optical attenuator 50b increases. That is, FIG. 11 supports the relationship between the optical output power and the generation threshold of stimulated Brillouin scattering described in FIG. 9B. In particular, based on these results, the semiconductor laser element portion of the semiconductor laser device according to the second embodiment is created by a detailed design such as adjustment of the number of modes, so that stimulated Brillouin scattering occurs with an optical attenuation of about 3 dB. It turns out that can be avoided.

FIG. 12 shows a multi-mode oscillation type semiconductor laser device having the characteristics shown in FIGS.
It is the graph which measured the scattering intensity ratio when changing the light intensity which injects into the optical fiber 24 for transmission using the measuring device of 0.

In the graph of FIG. 12, the scattering intensity is about −
Based on the case of 13 dB, by reducing the light intensity from 80 mW to 40 mW (corresponding to a reduction of about 3 dB or less), the scattering intensity ratio is about −13 dB to about −2 dB.
It drops to 9 dB. That is, in the semiconductor laser device having the scattering intensity ratio of about −13 dB in the measuring apparatus of FIG. 10, the light output is reduced by about 3 dB, and the scattering intensity ratio is suppressed to about −28 dB without causing stimulated Brillouin scattering. I understand that

The present inventors have found from such knowledge that the occurrence of stimulated Brillouin scattering can be suppressed by appropriately designing the attenuation amount of the optical attenuator section. FIG. 13 is a diagram showing the relationship between the reverse voltage applied to the optical attenuator unit and the amount of optical attenuation. In particular, this relationship is an experimental result obtained when the absorption length of the optical attenuator section is 300 μm.

In FIG. 13, ΔE represents the energy difference between the composition wavelength of the absorption layer 43 of the optical attenuator section and the laser oscillation wavelength of the semiconductor laser element section, and ΔE = E _sg (oscillation of the semiconductor laser element section). Wavelength energy) −E _ag (bandgap of the absorption layer 43 of the optical attenuator section). Therefore, from FIG. 13, the absorption layer 4 of the optical attenuator is shown.
It can be seen that as the composition wavelength of 3 becomes shorter than the oscillation wavelength of the laser of the semiconductor laser element portion, in other words, as ΔE becomes smaller, the amount of optical attenuation becomes smaller.

As can be seen from FIG. 13, if the reverse voltage applied to the optical attenuator section is increased, the optical attenuation amount can also be increased, but ΔE = −31.8 meV
At this time, the optical attenuation is about 2 dB even if the reverse voltage is increased. Therefore, in order to realize the optical attenuation of 3 dB or more in order to sufficiently suppress the stimulated Brillouin scattering, it is necessary to use a material having a longer wavelength composition than this. Further, even if the bandgap of the absorption layer 43 is too close to the oscillation wavelength energy of the semiconductor laser element portion, the light attenuation amount rapidly increases when a low voltage is applied, and thus it becomes difficult to finely control the light attenuation amount. Therefore, in order to achieve desired optical attenuation in the optical attenuator section, it is necessary to design the absorption length, thickness, and composition of the absorption layer 43 according to the oscillation wavelength energy of the semiconductor laser element section.

As described above, according to the semiconductor laser device and the semiconductor laser control method according to the second embodiment, a semiconductor laser element portion for outputting a plurality of oscillation longitudinal mode laser beams is provided on the same semiconductor substrate. , An optical attenuator integrated pumping light source is realized by forming an optical attenuator part for attenuating the laser light generated by the semiconductor laser device part and outputting it to the outside. Even when is fixed, the output power of the emitted laser light can be adjusted by controlling the drive current of the optical attenuator section. That is, the output power of the laser light can be adjusted, and the stable operation of the wavelength can be realized by fixing the injection current.

Further, by designing the optical attenuator section based on the oscillation wavelength energy of the semiconductor laser element section, it is possible to realize the optical attenuation capable of suppressing the stimulated Brillouin scattering.

(Third Embodiment) Next, a semiconductor laser module according to a third embodiment will be described. The semiconductor laser module according to the third embodiment is a mode in which the semiconductor laser device according to the first or second embodiment is enclosed in a package together with various optical components, and the laser light generated by the semiconductor laser device is transmitted to an optical fiber. It is modularized for the purpose of making it easily incident.

FIG. 14 is a vertical sectional view showing the structure of the semiconductor laser module according to the third embodiment. In FIG. 14, the semiconductor laser module 80 is provided on the inner bottom surface of a package 81 formed of ceramic or the like.
The Peltier element 120 described above is arranged. The base 110 described above is arranged on the Peltier element 120, and the semiconductor laser device 90 is arranged on the base 110. Here, semiconductor laser device 90 corresponds to the semiconductor laser device shown in the first or second embodiment.

The Peltier element 120 and the base 110
In the configuration including the semiconductor laser device 90, an electric current (not shown) is applied to the Peltier element 120 to perform cooling and heating depending on the polarity thereof. However, in order to prevent the oscillation wavelength shift due to the temperature rise of the semiconductor laser device 90, mainly. Functions as a cooler. That is, the Peltier device 120 cools and controls the temperature to a low temperature when the laser light has a longer wavelength than the desired wavelength, and when the laser light has a shorter wavelength than the desired wavelength. Is heated and controlled to a high temperature. This temperature control is controlled based on the detection value of a thermistor (not shown) arranged near the semiconductor laser device 90, and the control device (not shown) normally keeps the temperature of the semiconductor laser device 90 constant. The Peltier device 120 is controlled. Further, a control device (not shown) controls the Peltier element 120 so that the temperature of the semiconductor laser device 90 decreases as the drive current of the semiconductor laser device 90 increases. By performing such temperature control, the wavelength stability of the semiconductor laser device 90 can be improved, which is also effective in improving the yield.

In FIG. 14, an optical monitor 83, a first lens 84 and an isolator 85 are arranged on the base 110 in addition to the semiconductor laser device 90. Further, in the semiconductor laser module 80, the second lens 86 is arranged inside the portion where the optical fiber 82 is loaded.

The laser light emitted from the semiconductor laser device 90 is emitted from the first lens 84, the isolator 85 and the second lens 84.
The light is guided into the optical fiber 82 via the lens 86. The second lens 86 is provided on the package 81 on the optical axis of the laser light, and is optically coupled to the optical fiber 82 connected to the outside. The optical monitor 83 monitors and detects the light leaked from the reflective film side of the semiconductor laser device 90.

Further, due to the isolator 85 between the semiconductor laser device 90 and the optical fiber 82, the return light reflected by other optical components returns to the resonator and becomes stray light, which adversely affects the oscillation operation and the detection operation. It prevents it from being lost.

As described above, according to the semiconductor laser module of the third embodiment, since the semiconductor laser device shown in the first or second embodiment is modularized, the polarization-dependent isolator is used. The returned light can be made small, and it is possible to promote low noise and a reduction in the number of parts.

In the third embodiment described above, the example in which the isolator 85 is provided in the module has been shown, but the isolator is not necessarily an essential structure.

In the first to third embodiments described above, the oscillation wavelength λ ₀ of the semiconductor laser device is 1480 nm.
However, it is needless to say that the present invention can be applied to the case where a semiconductor laser element portion having another oscillation wavelength such as 980 nm is provided. Further, it goes without saying that the present invention can be applied not only to Raman amplifiers but also to EDFAs.

[0101]

As described above, according to the semiconductor laser device and the semiconductor laser control method of the present invention, a plurality of oscillation longitudinal modes below the threshold value which causes stimulated Brillouin scattering are generated on the same semiconductor substrate. Since an optical amplifier integrated pumping light source is realized by forming a semiconductor laser element section that outputs laser light and an optical amplifier section that amplifies the laser light generated by the semiconductor laser element section and outputs it to the outside. Even if the injection current of the semiconductor laser device section is fixed and reduced, the output power of the emitted laser light can be adjusted by controlling the drive current of the optical amplifier section. The output power can be adjusted, the stable injection wavelength can be achieved by fixing the injection current, and the occurrence of kinks due to the injection current can be prevented. An effect.

Further, according to the semiconductor laser device and the semiconductor laser control method of the present invention, a semiconductor laser element portion which outputs a plurality of oscillation longitudinal mode laser beams on the same semiconductor substrate, and the semiconductor laser element portion. Since an optical attenuator integrated pumping light source is realized by forming an optical attenuator section that attenuates the laser light generated in (1) and outputs it to the outside,
Even when the injection current of the semiconductor laser device is fixed, the output power of the emitted laser light can be adjusted by controlling the drive current of the optical attenuator unit. In addition to enabling adjustment, stable injection wavelength can be achieved by fixing the injection current,
Furthermore, the effect of suppressing the stimulated Brillouin scattering can be realized.

Further, according to the semiconductor laser module of the present invention, it is possible to provide the above-mentioned semiconductor laser device in the state of being enclosed in the package housing.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view in a longitudinal direction of a semiconductor laser device according to a first embodiment.

FIG. 2 is a sectional view taken along the line AA of the semiconductor laser device shown in FIG.

FIG. 3 is a diagram showing a graph for explaining a selective wavelength characteristic by the diffraction grating of the semiconductor laser device according to the first exemplary embodiment.

FIG. 4 is an explanatory diagram for explaining each profile of a laser light of a single longitudinal mode and a laser light of a plurality of oscillation longitudinal modes in the semiconductor laser device according to the first embodiment.

FIG. 5 is a diagram showing a relationship between an injection current and an oscillation wavelength in a semiconductor laser element section in the semiconductor laser device according to the first exemplary embodiment.

FIG. 6 is a diagram showing the relationship between the injection current and the output power of the semiconductor laser device section for each drive current of the optical amplifier section in the semiconductor laser device according to the first embodiment.

FIG. 7 is a vertical cross-sectional view of the semiconductor laser device according to the first embodiment formed by butt coupling.

FIG. 8 is a longitudinal cross-sectional view in the longitudinal direction of the semiconductor laser device according to the second embodiment.

FIG. 9 is a graph showing the relationship between the drive current and the optical output power together with the threshold value for the occurrence of stimulated Brillouin scattering.

FIG. 10 is a schematic diagram showing the structure of a measuring device for detecting the degree of occurrence of stimulated Brillouin scattering.

FIG. 11 is a graph showing the relationship between the attenuation amount and the scattering intensity ratio for six samples of the semiconductor laser device.

12 is a graph in which the scattering intensity ratio is measured when the intensity of light incident on the transmission optical fiber 24 is changed by using the measuring device of FIG.

FIG. 13 is a diagram showing the relationship between the reverse voltage applied to the optical attenuator section and the amount of optical attenuation in the semiconductor laser device according to the second embodiment.

FIG. 14 is a vertical sectional view showing a configuration of a semiconductor laser module according to a third embodiment.

[Explanation of symbols]

1 n-InP substrate 2,25,45 n-InP buffer layer 3,23 GRIN-SCH-MQW active layer 4 p-InP spacer layer 6,26,46 p-InP clad layer 7,17 p-InGaAsP cap layer 8 p-InP blocking layer 9 n-InP blocking layer 10, 20 p side electrode 11 n-side electrode 13 diffraction grating 14 Reflective film 15 Emitting side reflective film 21 separation groove 22 window area 43 Absorption layer 40 Blocking area 43 Active layer 50a, 90 semiconductor laser device 50b optical attenuator 51 coupler 53 Reflected light measuring means 54 Optical fiber for transmission 55 Input light measuring means 56 Output light measuring means 80 Semiconductor laser module 81 packages 82 optical fiber 83 Optical monitor 84 first lens 85 Isolator 86 Second lens 110 base 120 Peltier element

Claims (18)

[Claims] 1. A semiconductor laser device for generating laser light of a plurality of oscillation longitudinal modes by the wavelength selection characteristics of a diffraction grating formed between the emitting end face and the reflecting end face of laser light and near the active layer. And a semiconductor light adjusting unit that adjusts the output of the laser light while being integrated by sharing a semiconductor substrate on which the semiconductor laser element unit is formed. 2. The semiconductor laser device section includes at least one electrode of an electrode pair for applying a current, and at least one electrode of an electrode pair for applying a current to the semiconductor light control section, 2. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is electrically separated by a separation groove formed above a coupling boundary between the laser element portion and the semiconductor light adjusting portion. 3. The semiconductor light adjusting unit according to claim 1, wherein the semiconductor light adjusting unit has a laminated structure formed of a waveguide having a composition different from that of at least the active layer of the semiconductor laser device unit. Laser device. 4. The semiconductor laser element part has a reflection end face of the laser light as an end face, and a high reflection film is provided on the end face, and the semiconductor light adjusting part has the emission end face of the laser light as an end face, The semiconductor laser device according to claim 1, further comprising a low reflection film provided on the end face. 5. The semiconductor light adjusting unit is a laminated structure of semiconductor optical amplifiers for amplifying an output of laser light generated in the semiconductor laser device unit.
4. The semiconductor laser device according to any one of 4. 6. The semiconductor laser device according to claim 5, wherein the semiconductor optical amplifier has a laminated structure formed by sharing at least an active layer of the semiconductor laser element portion. 7. The semiconductor light adjusting unit has a laminated structure of semiconductor optical attenuators that attenuate the output of the laser light generated in the semiconductor laser device unit.
4. The semiconductor laser device according to any one of 4. 8. The semiconductor optical attenuator is characterized in that a high resistance layer is laminated on a separation groove formed above a coupling boundary between the semiconductor laser device portion and the semiconductor light adjusting portion. The semiconductor laser device described. 9. The semiconductor laser device according to claim 7, wherein the semiconductor optical attenuator has an absorption layer having an energy gap smaller or larger than the oscillation wavelength energy of the semiconductor laser element section. . 10. The semiconductor laser device section emits laser light at a laser oscillation time of 1200 nm or more at 160 nm.
It has a wavelength of 0 nm or less.
9. The semiconductor laser device according to any one of 9. 11. The resonator length is 800 μm or more and 3200.
11. The semiconductor laser device according to claim 1, wherein the semiconductor laser device has a thickness of μm or less. 12. The semiconductor laser device according to claim 1, wherein the diffraction grating of the semiconductor laser element portion has a diffraction grating length of 300 μm or less. 13. The diffraction grating length of the diffraction grating of the semiconductor laser device portion is equal to or less than a value of (300/1300) times the cavity length, according to claim 1. The semiconductor laser device described. 14. The semiconductor according to claim 1, wherein a multiplication value of a coupling coefficient of the diffraction grating of the semiconductor laser element portion and a diffraction grating length is 0.3 or less. Laser device. 15. The semiconductor laser device according to claim 1, wherein the diffraction grating of the semiconductor laser element portion has a grating period with a predetermined period fluctuation. 16. The semiconductor laser device according to claim 15, wherein the diffraction grating of the semiconductor laser element portion changes the grating period randomly or at a predetermined period. 17. The semiconductor laser device according to claim 1, an optical fiber that guides laser light emitted from the semiconductor laser device to the outside, the semiconductor laser device, and the light. A semiconductor laser module comprising: an optical coupling lens system for optically coupling with a fiber. 18. A semiconductor laser control method for controlling the output of laser light output from the semiconductor laser device according to claim 1, wherein a current applied to the semiconductor laser element section is fixed. A semiconductor laser control method, comprising: a step of adjusting a current or a voltage applied to the semiconductor light adjusting section.