JP2781182B2 - Compound semiconductor laser device having a waveguide - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a compound semiconductor laser device having a novel waveguide with high output, high speed, and high reliability.

[Conventional technology]

In a conventional vertical current path type semiconductor laser, a compound semiconductor laser in which a waveguide that does not absorb laser oscillation light is provided in a part of the cavity that goes from both ends to the inside was tried, and it was reported that the output was improved. (19
87, Proceedings of the 48th Annual Meeting of the Japan Society of Applied Physics p739,18a
-ZR-8). This device is a vertical NAH (Non Absorbing Mirro
r)-called LOC (Large Optical Cavity) laser,
It is less likely to cause self-absorption destruction of the mirror.

[Problems to be solved by the invention]

However, in the above-described vertical current path type semiconductor laser device, the structure is complicated and the substrate is conductive because of the vertical type, and it is difficult to integrate the substrate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a compound semiconductor laser device which can be easily integrated with other elements, has a large output, and can operate at high speed. .

[Means for solving the problem]

The compound semiconductor laser device having the waveguide according to the present invention is a lateral junction buried type (TJ-BH) which can be easily integrated with other elements.
And forming a waveguide by embedding a substance (a non-absorber) having a refractive index smaller than that of the active layer and not absorbing laser oscillation light in advance in a portion in contact with the active layer of the laser. The present invention is characterized in that the current injection layers are separately embedded and the non-absorber forms the end face of the resonator.

[Action]

According to the present invention, in a lateral junction buried heterostructure laser, a waveguide that does not absorb laser light is provided in a portion extending from both ends of the resonator toward the inside. Can be implanted, high output can be obtained, and since the lateral junction type is used, the substrate can be configured with semi-insulating properties. As a result, integration becomes easy, and the capacitance between electrodes is greatly reduced. Thus, high-speed operation can be performed.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a view showing one embodiment of a manufacturing process of the compound semiconductor laser device of the present invention.

First, as shown in FIG. 1 (a), semi-insulating GaAs: Cr
An undoped Al _0.42 Ga _0.58 As layer 2 of 2 μm, an undoped GaAs active layer 3 of 0.2 μm, an undoped Al _0.42 Ga
_{The 0.58} As layer 4 is grown 0.5 μm thick by epitaxy. SiNx is formed on this epitaxial substrate, and then, as shown in FIG. 1 (b), photolithography and etching are performed to a depth of 0.1 in parallel with the <10> direction of the figure.
8 μm stripe grooves 5 and 6 are formed. Then, undoped Al was added to stripe grooves 5, 6 by MOCVD using SiNx as a mask.
_{The 0.42} Ga _0.58 As layers 7, 8 are grown to 0.8 μm (FIG. 1 (c)). The undoped Al _0.42 Ga _0.58 As layers 7 and 8 do not absorb laser oscillation light because the undoped GaAs active layer 3 has a smaller dielectric constant, and thus a lower refractive index, and a larger band gap. Next, SiNx is removed by etching, and WNx is formed as a selective growth mask. A stripe groove 9 having a depth of 0.8 μm is formed in parallel with the <110> direction by photolithography and etching (FIG. 1 (d)), and then 0.8 μm of SiNx is formed. Then <10
> A stripe groove parallel to the direction and narrower than the interval between the previously formed stripes 7 and 8 is formed, and then an n-Al _0.35 Ga _0.65 As layer 10 is selectively grown on this window by MOCVD to obtain SiNx. Is removed by etching (FIG. 1E). The p-Al _0.35 Ga _0.65 As layer 11 is similarly buried (FIG. 1 (F)), and the inside of the layer buried parallel to the <10> direction (C ₁ , FIG. 1 (F)). C ₂ position)
Are cleaved to form cavity end faces (FIG. 1 (g)).

Then, when an electrode is formed on the cladding layers 10 and 11 and current is injected in the lateral direction to oscillate, the undoped layers 7 and
8 has a smaller refractive index than the active layer 3 and thus functions as a waveguide, and has a large band gap so that it does not absorb laser oscillation light and functions as a layer for preventing deterioration of the end face.

In addition, if the device surface is covered not only with the light emitting surface but also with a single type or a plurality of types of materials smaller than the refractive index of the active layer, it is possible to prevent leakage of laser oscillation light and improve oscillation efficiency. Can be.

In the above embodiment, the active layer 3 is exposed because the cladding layers 10 and 11 do not reach the undoped layers 7 and 8. This is because the active layer 3 is formed by the passivation to form an antioxidant film. The layers may be prevented from being oxidized, and the cladding layers 10 and 11 may be extended to the undoped layers 7 and 8 so that the carrier layer is not exposed.

Further, a material having a larger band gap, that is, a barrier layer is doped with n-type or p-type or both impurities to form a single quantum well structure or a plurality of single quantum well structures,
Alternatively, the efficiency of carrier injection into the active layer may be improved by forming a multiple quantum well structure to increase the output.

〔The invention's effect〕

As described above, according to the present invention, in a lateral junction buried heterostructure laser device, a vertical NAM (Non Absorbing Mirro
r) As in the case of -LOC (Large Optical Cavity) laser, a non-absorbing reflection mirror can be provided at the end face of the laser resonator, preventing the mirror from absorbing light and causing self-destruction, and providing a large output. Obtainable.

In addition, since a semi-insulating substrate can be used for the lateral junction laser, integration with other elements is easy, and the area for current injection can be significantly reduced as compared with the vertical type, thereby reducing the capacitance between electrodes. And high-speed operation can be performed.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a manufacturing process of the compound semiconductor laser device of the present invention. 1 ... Semi-insulating GaAs: Cr substrate, 2 ... Undoped Al _0.42 Ga
_0.58 As layer, 3 undoped GaAs active layer 3, 4 undoped Al _0.42 Ga _0.58 As layer, 5, 6 stripe groove, 7,8 undoped Al _0.42 Ga _0.58 As layer, 9 stripe groove, 10 n
-Al _0.35 Ga _0.65 As layer, 11 ... p-Al _0.35 Ga _0.65 As layer.

Continued on the front page (72) Inventor Satoshi Nagao 1000 Higashikanamachi, Ushiku City, Ibaraki Prefecture Inside Mitsubishi Chemical Research Institute (72) Inventor Yuichi Inoue 1000 Higashikianamachi, Ushiku City, Ibaraki Prefecture Mitsubishi Chemical Corporation (56) References JP-A-60-198883 (JP, A) JP-A-59-13387 (JP, A) JP-A-62-214687 (JP, A) (58) Fields investigated (Int. . ^6, DB name) H01S 3/18

Claims (7)

(57) [Claims] In a lateral junction buried heterostructure laser device, a waveguide that does not absorb laser oscillation light is provided in a region extending from both ends of the resonator to the inside so as to cover the active layer end surface with substantially the same width as the active layer end surface. A compound semiconductor laser device characterized by being provided. 2. The compound semiconductor laser device according to claim 1, wherein the active layer has one or more single quantum well structures. 3. The compound semiconductor laser device according to claim 1, wherein the active layer has a multiple quantum well structure. 4. The compound semiconductor laser device according to claim 1, wherein the active layer has a single quantum well structure or a single quantum well structure in which a barrier layer is selectively doped with one conductivity type impurity. 5. The compound semiconductor laser device according to claim 1, wherein the active layer has a multiple quantum well structure in which a barrier layer is selectively doped with an impurity of one conductivity type. 6. The compound semiconductor laser device according to claim 1, wherein the active layer has a multiple quantum well structure in which a barrier layer is selectively doped with impurities of both conductivity types alternately. 7. The compound semiconductor laser device according to claim 1, wherein the light-emitting surface and the device surface are covered with a single material or a plurality of materials smaller than the refractive index of the active layer.