JPS6344785A - Semiconductor laser array - Google Patents

Abstract

PURPOSE:To suppress a 180 deg. phase synchronous mode and provide a high-fidelity semiconductor laser array device that make oscillations with a single 0 deg. phase synchronous mode by preparing a groove part at the junction surface of a substrate where a width of a groove is narrower than a total size of widths of respective emission regions and its groove has a prescribed depth. CONSTITUTION:A groove part 3 is formed at the upper surface of a substrate 2, and then a clad layer 4, an active layer, the clad layer 6 and electrode formation layers 7 are grown. And then ridges 8 are formed and when a width size WS of the groove part 3 becomes narrower than the width size WL that is almost equal to the total widths of respective width sizes of the ridges, a thickness of the clad layer 4 at a central part of an array is deeper than those of peripheral parts of the array and accordingly a stripe equivalent refractive index in the clad layer 4 increases. Yet, on the contrary, a loss due to absorption of the substrate 2 becomes so large that at the central part of the array there is a refracting distribution which is of advantage to a 0 deg. phase mode oscillation having a large field strength and at each part of the array there is a loss distribution where a 180 deg. phase synchronous mode having the same strength is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention is applicable to semiconductor laser array devices that can oscillate in a single mode and obtain high output, for example, used in optical communications and optical information processing equipment such as optical disk players. Seki, that's what I do.

(b) Prior Art Generally, semiconductor laser array devices are known in which a plurality of semiconductor lasers are integrated in order to obtain high output. As for its structure, for example, one semiconductor laser is made of n-type GaAffAs on a flat n-type GaAs substrate.
After sequentially forming a cladding layer, a CaAs active type GyuAQAs cladding layer, and a p-type GaAs cap layer,
A ridge waveguide laser element having a structure in which all of the left and right sides of the cap layer and a portion of the left and right sides of the cladding layer are removed by etching, and SiO* insulating layers are formed on both left and right surfaces of the cladding layer, is fabricated on one substrate. It is formed by stacking three pieces on top.

(c) Problems to be Solved by the Invention However, in the above structure, oscillation in a single 0° phase locking mode has not been achieved, and therefore high output has not been achieved. This is because the high-order 180° phase locking mode oscillates with a low threshold gain. The gain difference between the exactly 0° phase locking mode and the 180° phase locking mode is extremely small, so either the two modes oscillate mixedly, or rather, the gain between the ridges is small and the 180° phase locking mode is extremely small.
The oscillation in the phase-locked mode is the main one.

This invention was made in view of the above circumstances, and 180
It is an object of the present invention to provide a semiconductor laser array device that suppresses the phase-locked mode and oscillates in the phase-locked mode.

(d) Means for Solving the Problems The present invention has a configuration in which a plurality of semiconductor lasers are integrated on the same substrate, and in a semiconductor laser array device comprising a plurality of light emitting regions, the substrate faces the light emitting region. A semiconductor laser array device is characterized in that a groove portion having a width smaller than the sum of the widths of the respective light emitting regions and a predetermined depth is provided on the bonding surface of the semiconductor laser array device.

(E) Effect The refractive index in the groove portion is the highest and absorption of higher-order modes is increased in the peripheral portion other than the groove portion, so that 0° phase oscillation can be stably obtained.

(F) EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following examples.

A semiconductor laser array device I shown in FIG. 1 is a three-stripe semiconductor laser array device.

2 is a p-type GaAs substrate with a radius 6 on its top surface (junction surface).
Grooves 3 each having a depth of 1 μm are formed in a stripe shape.

That is, the groove portion 3 extends in the longitudinal direction of the resonator (not shown) of the semiconductor laser array device 1. Then, on the substrate 2 processed as described above, a p-type GaAffAs cladding layer 4, a GaAQAs active layer 5, an n-type GaA12As
Ω-type GaAsR for cladding layer and electrode formation
7 are grown by liquid phase epitaxial method. Next, a width of 2 μm S is formed around the groove 3 formed in the substrate 2.
Ridges 8 with a spacing of 2 μm are formed by reactive etching. Furthermore, an SjN film 9 for current blocking is formed on the surface of the n-type GaAs layer 7 for electrode formation except for the top surface and the surface of the p-type GaAl2As cladding layer 4, and continues on the top surface and the top surface of the n-type GaAs layer 7 for electrode formation. Then, an n-type electrode IO is formed. 1] is a p-type electrode provided on the lower surface of the substrate 2. Thereafter, the wafer is divided into individual semiconductor laser array devices I using a conventional method.

In this embodiment, the width of the light emitting areas 121° 12b, 12c below the respective glue horns 8, or in other words, the width WL which is approximately equal to the sum of the widths of the respective glue horns 8, is determined by the width of the groove 3. The width dimension ws of is small (W5 < Ww). Therefore, due to the groove portion 3, the layer thickness of the p-type GaA/As cladding layer 4 becomes larger at the center of the array than at the periphery of the array, and the equivalent refractive index of the stripe of this p-type GaA/IAs cladding layer 4 increases. On the contrary, in the peripheral area, the loss is large due to absorption by the substrate 2.

Therefore, the semiconductor laser array device of the present invention has a refractive index distribution that is advantageous for the 0° phase mode 1 oscillation, with a large electric field strength at the center of the array, and a loss distribution that suppresses the 180° phase synchronization mode with the same intensity in each part of the array. It becomes.

In this example, the front resonance surface was coated with a transmission film and the back resonance surface was coated with a high reflection film, and single 〇゛ phase oscillation was obtained up to an output of 300 mW.

This method can also be applied to other real guide lasers, such as embedded guides and rib guides.

In the above embodiment, the semiconductor laser array device has three ridges, but the number of ridges may be increased or decreased depending on the desired output.

(G) Effects of the Invention According to this invention, only a single 〇゛ phase-locked mode oscillation can be detected from among multi-mode oscillations including high-order transverse modes by giving a distribution to the equivalent refractive index of the cladding layer. A semiconductor laser array device can be obtained that can perform laser oscillation extremely stably and with high main power.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention. 2...Substrate, 3...Groove, 12a
, +2b, 12c... Light emitting region. Figure 1

Claims (1)

[Claims] 1. In a semiconductor laser array device having a plurality of light emitting regions by integrating a plurality of semiconductor lasers on the same substrate, each light emitting region is provided on a bonding surface of the substrate facing the light emitting region. What is claimed is: 1. A semiconductor laser array device comprising a groove portion having a width smaller than the sum of the widths of and a predetermined depth.