JPH0225087A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To enable the supermulti-oscillation of a semiconductor laser by a method wherein a laser and a distributed reflecting section are formed on the same position on the same substrate to form the semiconductor laser of a Fourier resultant wave type structure. CONSTITUTION:In a distributed reflection type semiconductor laser which oscillates concurrently in two wavelengths, if the period of a distributed reflection section 3 is l, l is represented by an equation, l=l/2ne (where ne denotes the refractive index of the distributed reflection section 3). Therefore, if l is made to change, the semiconductor laser oscillates in different wavelengths correspondingly. And, if the distributed reflection section 3 is constituted in such a manner that the laser oscillate a resultant wave that two wavelengths lambda1 and lambda2 of two periods l1(=lambda1/2ne) and l2 (=lambda2/2ne) are compounded together, the reflectivity of this part from an active section 2 side as a basis is high toward the wavelengths lambda1 and lambda2. In the combination of a reflector and a laser obtained as mentioned above, if an interval between lambda1 and lambda2 is large to a certain extent, light rays of the wavelengths lambda1 and lambda2 can be concurrently oscillated, so that wavelengths lambda1, lambda2... can be set independently of each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention relates to a semiconductor laser that performs stable multi-wavelength simultaneous oscillation, and in particular to a so-called distributed reflection type (DBR) semiconductor laser in which the reflection section is The present invention relates to a semiconductor laser device having a Fourier-synthesized waveform structure in which periods corresponding to multiple wavelengths are synthesized instead of a single period in order to simultaneously obtain high reflectance at multiple wavelengths.

[Prior Art] As shown in FIG. 4, a conventional multi-wavelength simultaneous oscillation semiconductor laser has two active parts 2 and one distributed reflection part 3 for each wavelength on a single substrate 1 at different locations. were made, and current was supplied independently from the electrode lead wires 4 provided to each to cause oscillation.

This allows simultaneous oscillation of multiple wavelengths with a relatively small size. In the case of Fig. 4, λ1. λ2. λ3゜λ4. λ, no 5
The wavelength can be obtained. Note that IL, . . . , 15 indicates the period of the distributed reflection section 3.

(Problems to be Solved by the Invention) However, the above conventional technology has the following problems.

■ Since the active part 2 and distributed reflective part 3 of the semiconductor laser for each wavelength are fabricated at different positions on the substrate 1, there are problems with crystal non-uniformity of the active part 2 and distributed reflective part 3 and limits of processing accuracy. Due to differences in heat distribution and heat distribution, each oscillation wavelength λ1. There are variations in the accuracy of .

Furthermore, due to heat generation, only about five wavelengths could be incorporated on the same substrate 1.

■ Since lasers are created for each wavelength at an independent position, the size becomes enormous if more wavelengths (100 to 1000) are required.

The present invention was made to solve the above problems, and an object of the present invention is to provide a semiconductor laser device that is compact and capable of oscillating multiple wavelengths.

[Means to solve the problem]

In the semiconductor laser device according to the present invention, the periodic structure of the distributed reflection section or the distributed feedback section is a Fourier synthesis waveform structure for multiple wavelengths.

[Effect]

In this invention, since the periodic structure of the distributed reflection section or the distributed feedback section has a Fourier composite waveform structure for multiple wavelengths, laser light of multiple wavelengths included in this Fourier composite waveform is output.

〔Example〕

FIG. 1 is a side view showing an embodiment of the present invention. For the sake of simplicity, this embodiment shows the case of simultaneous oscillation of two wavelengths. In a distributed reflection semiconductor laser (DBR), its oscillation wavelength λ is given by the following, where L is the period of the distributed reflection section 3. Here, no is the refractive index of the distributed reflection section 3. Therefore, if the period °C is changed, oscillation occurs at a different wavelength accordingly.

If the periodic structure of the distributed reflection section 3 is as shown in Fig. 2,
In other words, (i) is the sum of (i) and (if) in Figure 2.
As shown in ii), it can be easily produced by the blowfish method or the like. Furthermore, this structure has two
The configuration is not limited to wavelengths, and it is possible to configure up to about 1000 wavelengths at the maximum, and as a result, simultaneous multiplex oscillation of up to about 1000 wavelengths is possible. In the combination of the reflector and laser thus obtained, λ1. If the interval λ2 is larger than a certain degree (so-called uniform spread width 1 to 3 GH), the wavelength λ1°λ2. . . . can be oscillated simultaneously, and the wavelength λ1. λ2. . . . can be set independently (at the processing stage).

As shown in Fig. 2, the reflectance of the distributed reflection section 3 having the I) BR section, which has a structure that is a combination of two (multi) periods, is as follows for each period II I + Jl,, l... ...
・The wavelength λ1. λ2. ... exhibits high reflectance. On the other hand, the amplification degree of the active part 2 of the semiconductor laser exhibits a considerable so-called average spread (10 THz or more). Due to this average spread, the wavelength λ1. λ2.・・・
The lights of ... can oscillate independently if the interval between them is wide enough. Edge-reflection lasers that do not have a normal distributed reflector often exhibit multi-axis mode oscillation. The reason for this is due to the mean-spreading phenomenon of semiconductor materials. In this case, the oscillation wavelength is determined by λ=2L-n,/m. Here, L indicates the state of multiple oscillation when the rays and surfaces at both ends of the semiconductor laser are used as reflective surfaces.

In this way, the amplification degree of the active part 2 of the semiconductor laser is -
Since it has a spread, different wavelengths λ1 . λ2. If a reflector with high reflectance is attached to the required laser body, the wavelength λ
1. λ2. ...and oscillate at the same time.

Note that in FIG. 3, since the amplification degree changes depending on the wavelength, each wavelength λ1. λ2. If the reflectance of the distributed reflection section 3 for . Such output characteristics are not practical.

According to the present invention, this problem can be solved by a simple device. That is, in FIG. 2, the amplitude al+ of the periodic structure with respect to wavelength λ1, the amplitude 82 with respect to λ1, etc. are set to different values in order to provide reflectances that are inversely proportional to the amplification degree of the active part 2 for each wavelength. In this way, the overall amplification including the reflectance can be made substantially constant for each wavelength. As a result, the output has a wavelength λ1. λ2.・・・・・・
・Can be set almost constant.

(Effects of the Invention) As explained above, this invention uses the periodic structure of the distributed reflection section or the distributed feedback section as a Fourier synthesis waveform structure for multiple wavelengths, so that ultra-multiplexed oscillation of a semiconductor laser, which was previously impossible, is achieved. I can do it. That is, as in the conventional example shown in Fig. 4,
With lasers constructed on the same substrate, the limit was at most 5 multiplexed oscillations with a wavelength interval of 5 people, but according to this invention,
Up to 1000 multiplexes are possible with an interval of 0°05 people. This is because the distortion and thermal effects of the crystal have the same effect on all wavelengths because the laser and the distributed reflector are fabricated at the same location on the same substrate, so the oscillation wavelength is randomly generated relative to the design value. They cannot overlap and interfere with each other. Even if variations exist, they occur simultaneously and in the same direction for all oscillation lines. moreover,
When a DBR or DFB laser is operated at a single wavelength, only one tree in FIG. 3 oscillates, so all the energy in the other wavelength ranges is actually wasted. According to this invention, all of this part also contributes to oscillation, so that the energy utilization efficiency as a whole becomes extremely high.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of the present invention, FIG. 2 is a diagram explaining the configuration of the distributed reflection section of the present invention, FIG. 3 is a diagram explaining multi-axis mode oscillation of a semiconductor laser, and FIG. 1 is a perspective view showing an example of a conventional multi-wavelength simultaneous oscillation semiconductor laser. In the figure, 1 is a substrate, 2 is an active part of a semiconductor laser, 3 is a distributed reflection part, and 4 is an electrode lead wire. Figure 1 Figure 3 □~30THz Figure 2 (iii)

Claims (1)

[Claims] In a distributed Bragg reflection type or distributed feedback type semiconductor laser device, in order to obtain simultaneous oscillation of multiple wavelengths, the periodic structure of the distributed reflection part or the distributed feedback part is a Fourier synthesis waveform structure for multiple wavelengths. Semiconductor laser equipment.