JPH01260878A - Semiconductor laser for emitting light beams at multiple points - Google Patents

Abstract

PURPOSE:To decrease electric interference among light emitting points, by forming a multiple point light emitting laser diode by growing a crystal on an insulating substrate, and forming an isolating groove which isolates the light emitting points so as to reach the insulating substrate. CONSTITUTION:On an insulating substrate 8, e.g., on a Cr doped GaAs substrate, p-type GaAS contact layers 7a and 7b and n-type GaAs current blocking layers 6a and 6b are grown in a liquid phase or a vapor phase. Current injecting grooves 10a and 10b are formed by etching. Then, p-type AlyGa1-yAs second clad layers 5a and 5b, p-type AlxGa1-xAs active layers 4a and 4b, n-type AlyGa1-yAs first clad layers 3a and 3b and n-type GaAs contact layers 2a and 2b are sequentially grown as crystals. Furthermore, an isolating groove 9 is formed by etching so as to reach the insulating substrate 8. Thus, light emitting points 1a and 1b are completely isolated electrically. Electrode parts 11a and 11b are formed so as to form electrodes by etching so that parts of the electrode parts are exposed on the surfaces of the p-type GaAs contact layers 7a and 7b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multi-point emitting semiconductor laser that independently outputs laser light from a plurality of light emitting points, and more specifically, relates to a multi-point emitting semiconductor laser that is formed on a single substrate. This invention relates to a so-called monolithic multi-point emitting semiconductor laser.

[Prior Art] Conventionally, there is a semiconductor laser of this type, a so-called independently driven semiconductor laser, as shown in FIG. The semiconductor laser shown in FIG. 3 has two light-emitting points 1a, lb, and for each light-emitting point 1a, 1b, an n-type contact layer 2a, 2b, an n-type contact layer 2a, 2b, and an n-type contact layer 2a, 2b. Cladding layer 3a, 3
b, active layer 4a, 4b 1p type second cladding layer 5a
, 5b, and p-type current blocking layers 6a, 6b, respectively. Furthermore, the p-type substrate 12 has a self-luminous point 1a.
, lb, and 13 is the self-luminous point 1a, l
This is a separation groove for electrically isolating b.

In this two-beam laser array diode, for example, when driving the light emitting point 1a, the n-type contact layer 2
A forward bias is applied between a and the p-type substrate 12 to inject a current into the active layer 4a.

Further, when driving the light emitting point 1b, a forward bias is similarly applied between the n-type contact layer 2b and the p-type substrate 12.

Generally, the distance between the two light-emitting points 1a and 1b is often set to about 100 μm due to problems such as aberrations of lenses in the optical system and light collection efficiency.
It becomes possible to condense the optical outputs from a and lb using a common optical system and utilize them independently.

Therefore, by applying such semiconductor lasers to optical disk memories, laser printers, etc., two or more laser beams can be operated simultaneously and at high speed.
This means that high functionality can be achieved.

[Problems to be Solved by the Invention] However, in the conventional multi-point emitting semiconductor laser, as described above, the p-type substrate 12 on one electrode side has both light emitting points 1a.
, lb, the light emitting points 1a cannot be separated only by the separation groove 13.

It cannot be said that lb is completely electrically isolated, and therefore mutual electrical interference occurs.

For example, if one light emitting point 1a is being driven with a constant light output and the other light emitting point 1b starts to be driven, the previous output of the one light emitting point 1a will change accordingly. Therefore, for example, when used in the above-mentioned optical disk memory, etc., errors will occur due to fluctuations in optical output.

The present invention has been made in view of the above points, and an object of the present invention is to reduce electrical interference between light emitting points in a monolithic multi-point light emitting semiconductor laser.

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the multi-point emitting semiconductor laser of the present invention, a multi-point emitting laser diode that outputs laser light from a plurality of light emitting points is Separation grooves are formed on the substrate by crystal growth, and reach the insulating substrate to separate the light emitting points of the laser diodes from each other.

[Function] According to the above configuration, the separation groove reaching the insulating substrate allows the p
The type and n-type picture electrodes are also completely separated,
Furthermore, due to the high resistance of the insulating substrate, electrical interference can be almost ignored. Moreover, because it is a so-called monolithic type laser diode with multi-point emitting laser diodes formed on a single insulating substrate, the optical output is higher than that of a so-called hybrid type laser diode that is configured on separate substrates. There is no variation, and it is suitable for mass production.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the structure of a multi-point emitting semiconductor laser according to an embodiment of the present invention. This embodiment shows a two-beam semiconductor laser, and is similar to the conventional example of FIG. Corresponding parts are given the same reference numerals.

In the same figure, Ia and lb are two light emitting points, and n-type contacts 112a and 2b are connected to each light emitting point 1a and lb.
Sn-type first cladding layer 3a, 3b, active layer 4a,
Jb Sp type second cladding layers 5a, 5b and 1p type current blocking layers 6a and 6b correspond to each other, and this structure is basically the same as the conventional example shown in FIG.

7a, 7b are p-type contact layers, 8 is an insulating substrate, 9
is a #l groove separating each light emitting point 1a and lb.

In this embodiment, the above-mentioned n-type contact layer 2a.

2b, n-type first cladding layer 3a, 3b, active layer 4a
, 4b, p-type second cladding layer 5a, 5b, p-type current blocking layer 6a, 6b and p-type contact layer 7a
, 7b is formed on an insulating substrate 8, and furthermore, a separation groove 9 is formed to reach the inside of the insulating substrate 8, whereby p-type contact layers 7a, 7b are formed. are electrically isolated from each other so as to individually correspond to each light emitting point 1a, lb.

Next, the manufacturing procedure of the semiconductor laser having the above structure will be explained based on FIG. 2.

First, the insulating substrate 8 shown in FIG. 2(A), for example,
As shown in FIG. 2(B), a p-type GaAs contact layer 7a is formed on a GaAs substrate doped with C.
, 7b and n-type GaAs current blocking layers 6a, 6
b is grown in liquid phase or vapor phase to form current injection groove 10a,
10b is formed by etching.

Next, as shown in FIG. 2(C), a p-type Al yGa l YAS second cladding layer 5a is formed by liquid phase growth.
, 5b, p-type AlxGa, -xAs active layer 4a
, 4b, n-type AI YGa 1-YAS first cladding layer 3a, 3b, n-type GaAs contact layer 2
Crystals a and 2b are grown sequentially.

Furthermore, as shown in FIG. 2(D), a separation groove 9 is formed by etching to reach the insulating substrate 8 to completely isolate the light emitting points 1a and lb, and furthermore, electrode formation is performed. By etching, p-type GaAs
The surfaces of contact layers 7a and 7b are partially exposed to form electrode portions 11a and 11b, thereby obtaining the semiconductor laser shown in FIG.

In the multi-point emitting semiconductor laser of this embodiment, when driving the light emitting point 1a, a forward bias is applied between the n-type contact layer 2a and the p-type contact layer 7a. Similarly, when driving the light emitting point 1b, the n-type contact layer 3b and the p-type contact layer 7b
It is driven by applying a forward bias between the two.

In this way, a multi-point emitting type laser diode is formed on the insulating substrate 8 by crystal growth, and each light emitting point 1a, I
Since the isolation groove 9 that completely separates the light emitting points 1a and 1b is formed to reach the insulating substrate 8, that is, to separate the p-type contact layers 7a and 7b from each other, each light emitting point 1a,
lb electrical interference will no longer occur. Note that the insulating substrate 8
For example, the electrical resistivity of a commonly used Cr-doped GaΔS substrate is about 10 8 Ωcm, and the leakage current due to the substrate can be virtually ignored. Furthermore, since the semiconductor laser of the present invention is of a monolithic type, there is extremely little variation in the characteristics of each end output compared to a hybrid type semiconductor laser configured on separate substrates, and it is superior in terms of mass productivity.

Although the At Ga As laser was described in the above embodiment, the present invention is not limited to this.
Of course, the present invention can also be applied to other lasers such as InGaAs lasers.

[Effects of the Invention] As described above, according to the present invention, a multi-point emitting type laser diode is formed on an insulating substrate, and a portion MWII for separating each light emitting point of the laser diode from the insulating substrate is formed on the insulating substrate. Since the light-emitting points are formed so as to reach the transparent substrate, each light-emitting point can be completely electrically isolated, and there is almost no electrical interference between the light-emitting points, so that each light-emitting point can be driven completely independently.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a multi-point emitting semiconductor laser according to an embodiment of the present invention, FIG. 2 is a diagram showing the manufacturing procedure of the embodiment of FIG. 1, and FIG. 3 is a diagram showing the structure of a conventional example. FIG. la, lb... Light emitting point, 8... Insulating substrate, 9...
... Separation groove.

Claims (1)

[Claims] A multi-point emitting laser diode that outputs laser light from a plurality of light emitting points is formed on an insulating substrate by crystal growth, and separation grooves that separate the light emitting points of the laser diode from each other reach the insulating substrate. A multi-point emitting semiconductor laser formed as follows.