JPS6242590A - Semiconductor laser array device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor laser array device that can be used as a light source for optical information processing and optical communications.

2. Description of the Related Art In recent years, the output of semiconductor lasers has been increased as light sources for laser printers, optical information recording such as video recording, optical communication, and the like. The most promising structure for increasing output power is a phase-locked semiconductor laser array device. This is a one-chip integrated laser in which multiple laser diodes are arranged on one chip so that the spacing between them is sufficiently small that optical coupling between adjacent diodes is achieved. . In such a semiconductor laser array device, as a result of strong optical coupling, each laser oscillates with the same phase, and the laser light output emitted by each diode is combined to form a large output and a single beam with a wide width. will be obtained.

Problems to be Solved by the Invention However, conventional laser array devices do not take any measures to stabilize the longitudinal mode, so the oscillation wavelength changes due to changes in the external environment such as temperature, and related problems occur. It was not possible to suppress the generation of noise. One solution to this difficulty is to create wavelength selection by creating periodic notches in the active layer of the laser.
B (DistributeclFeaack)
Although a laser structure is adopted, this manufacturing method is extremely difficult, resulting in poor yield and mass production.

□Means for solving the problem In order to solve the above problem, the semiconductor laser array device of the present invention has a plurality of striped electrodes having a width that changes periodically along the direction of the optical axis of the laser cavity. The laser diode is arranged sufficiently close to each other.

Operation With this configuration, the current distribution in the active layer of each individual diode, and therefore the gain, changes periodically along the optical axis of the cavity, for reasons similar to those of a DFB laser.
Longitudinal mode stability is obtained.

The optical coupling of individual diodes stabilized in the same longitudinal mode results in a phase-locked laser array device.
The synergistic effect of mode stabilization results in a highly mode-stabilized product. Since the above-mentioned stripe electrode formation is extremely simple based on conventional techniques, a highly mode-stabilized phase-locked laser array device can be obtained with high yield and mass productivity.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of a semiconductor laser array device according to an embodiment of the present invention. In FIG. 1, 1 is Zn.
Diffusion layer 2 has a thickness of 0.674m and an impurity concentration of 5×10
n-GaAs of crn, 3 is P-Ga0.6All with a thickness of 0.6 μm and an impurity concentration of 1×1o crn
0.4As cladding layer, 4 is 0.1 μm thick and undoped GaAs active layer, 5 is 1.5 μm thick and impurity concentration 5
×10 crn of N-Gao, 6AnO, 4A
s cladding layer, 6 is n-GaAg substrate, 7 is T
i /P t /Au alloy electrode, 8 is Au/G@7 public i alloy electrode.

A plan view showing the striped shape of the Zn diffusion layer 1 is shown in FIG. The wide width of the stripes is 20 μm, the length of each part is 0.48 μm, the width of each narrow part is 4 μm, the length of each part is 0.48 μm, and the gap between the narrow stripes is 1 μm. The laser length in the stripe length direction is 2
50 μm, which is the cavity length.

The operation of the semiconductor laser array device configured as described above will be described below. First, the electrode element is positively biased with respect to the electrode 8. Then, holes are injected from the Zn diffusion layer 1 to the active layer 4, but since n -GaAs+ 2 blocks the hole current, the holes in the active layer 4 are concentrated in the vicinity directly under the Zn diffusion layer 1, and the holes are injected into the active layer 4. It recombines with the electrons injected from 8 and produces laser operating sound. That is, the recombination of holes and electrons occurs in the vicinity directly below the stripes of the Zn diffusion layer 1 shown in FIG. 2, and the gain is not zero only there. That is, the gain changes periodically in the cavity direction, and therefore the effective refractive index also changes with the same period. This period is 0.96 μm, which is four times the material wavelength of the laser light. for that,
Oscillations of many longitudinal modes with different wavelengths other than those determined by this period are strongly suppressed, and mode stabilization is achieved. The period was selected to be about 1 μm because below this value, the disadvantage of gain blurring due to carrier diffusion becomes serious. In reality, the range in which oscillation occurs is about the narrow width of a stripe, so oscillation occurs in two independent stripes, and the two oscillations are optically coupled, resulting in phase-synchronized laser array operation. is obtained. The role of the cladding layers 3 and 6 is to confine injected electrons and holes in the active layer 4, respectively, and at the same time to concentrate the emitted laser light in the active layer 4, thereby reducing the operating current value. It is to let.

As described above, according to this embodiment, a mode-stable semiconductor laser array device can be obtained with a simple configuration in which two lasers using two striped Zn diffusion layers 1 are placed close to each other.

The semiconductor laser array device of the present invention has Z
This can be achieved by forming an n-layer and forming each layer by liquid phase epitaxial growth, but these techniques are well established and can sufficiently ensure yield and mass production.

In this embodiment, the stripes providing the two laser beams are connected over a wide portion, but this is not necessary and they may be separated. Furthermore, although the external stripe structure has been discussed here, the same method can be used for the internal stripe structure as well, without being limited thereto.

In addition, the materials are not limited to those of the examples, and the active layer is made of Ga 1-xAn xAs- and the cladding layer is made of Ga.
1-aA2aA8 may be used under the condition of y>x.

Furthermore, InGaAsP, GaAnAsP, In
As, Pb5nTe.

The structure of the present invention can also be used for materials such as HgCdTe. In particular, Pb5nTe 9 HgCdTe
In a long-wavelength laser using a laser beam, the wavelength within the material of the laser beam is several times that of the example, so even if the stripe period is made the same as the wavelength, the obstacle of gain blurring due to carrier diffusion can be ignored. Therefore, mode stability is particularly excellent.

Effects of the Invention As described above, the semiconductor laser array device of the present invention has a non-uniform structure in which the shape changes periodically along the length direction of the cavity, and the period is a half-integer multiple of the wavelength within the material of the laser beam. A plurality of laser diodes each having a current confinement region in the form of a stripe are integrated on a single chip so that the stripes are parallel to each other, and the distance between the lasers is set to the extent that optical coupling between adjacent lasers is ensured. It is constructed with a small size and can be manufactured with high yield and mass productivity using established conventional laser manufacturing technology.It exhibits high output operation with stable mode and phase synchronization, and its practical effects are great. be.

[Brief explanation of drawings]

Figure 1 is a sectional view of a laser in an embodiment of the present invention, Figure 2 is a cross-sectional view of a laser in an embodiment of the present invention;
The figure is a plan view of a Zn diffusion layer of a semiconductor laser array device in an embodiment of the present invention. 1...Zn diffusion layer, 2...old...n-GaAs
, 3...P-Gao, 6Allo, 4A
s, 4=-=-GaAa, 6---N-Gao,
615J1. o, 4Ats, e ・−・・−n −G
aAs substrate, 7... mark, T i /P t /Au 7
oi, 8-.-Au/Ge/Ni alloy.

Claims (1)

[Claims] A plurality of laser diodes are adjacent to each other and each has a stripe-shaped current constriction region whose width changes periodically along the length direction of the cavity at a period that is a half-integral multiple of the set wavelength of the laser light in the substance. A semiconductor laser array device characterized in that stripes are arranged parallel to each other and integrated on the same substrate at intervals sufficiently small to ensure optical coupling between diodes.