JPS62272579A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To easily alter the directivity of an emitted light from a semiconductor light emitting device by providing phase adjusting functions independently in a plurality of optical guides in which a laser output is branched to alter the phase of a propagated light independently in the guides. CONSTITUTION:An optical guide type optical branch is provided at the laser output unit CLD of a laser oscillation region LDOSC of a semiconductor light emitting device having the regions LDOSC and an optical guide region LDCONT on the same substrate 1. A laser light branched by the branch are propagated, and optical guides 3, 4 having independent phase adjusting mechanisms 5, 6 and light emitting ends provided in the guides 3, 4 are provided. The mechanisms generate variations in refractive index by supplying a current to the P-N junction of the guide and varying a current density (where when the current density rises, the refractive index of the optical guide layer of the optical guide decreases.), thereby varying the phase of the light propagated in response thereto. Or, the phase is adjusted by applying an electric field to the guide.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Summary] This is a semiconductor light emitting device having a laser, a light branching mechanism, and a phase adjustment mechanism on the same substrate, making it possible to control the directivity of emitted light.

[Industrial application field]

The present invention relates to an array-shaped semiconductor light emitting device, and particularly to a structure for making the directivity of emitted light variable.

[Conventional technology]

Conventionally, an S-product array type semiconductor laser has the feature that the directivity of emitted light can be changed by changing the oscillation state of each laser.

Conventional integrated array semiconductor lasers have a structure in which multiple laser active layers are arranged in parallel (some have been made, but it is difficult to control the oscillation state of each laser independently, so the direction of the emitted light is The drawback is that you cannot change your gender much.

FIG. 5 shows a conventional semiconductor light emitting device.

In the figure, an n-GaAs substrate 51 is
Aff As cladding layer 52, n-GaAnAs active layer 53, p-GaAj2As cladding layer 54, p''
A GaAs contact layer 55 is formed. The lower cladding layer 52 is partially thick (formed), and electrodes 57 and 58 are provided in the windows provided in 5iOzll*56 above this part, and electrodes 59 are provided on the back side of the substrate 51. ing.

With this configuration, laser oscillation occurs at the thicker portions 52A and 52B of the lower cladding layer 52.

That is, the configuration is such that two lasers coupled in the lateral direction are arranged, and the current of each laser can be applied separately. Therefore, the left and right laser electrodes 5
By changing the current flowing through 7 and 58, the oscillation state of the laser changes, the way light is coupled changes, and the directivity of the emitted light changes.

[Problem that the invention seeks to solve]

However, in the conventional semiconductor light emitting device described above, since the oscillation state of the laser itself is changed, changing the laser current changes the oscillation wavelength, etc., making it difficult to control only the wavefront of the emitted light. There is a problem that it cannot be used unless certain conditions are met.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an array type semiconductor laser in which the directivity of laser light emitted from the laser is improved.

[Means for solving problems]

The present invention provides a semiconductor light emitting device in which a laser oscillation region and a waveguide region having a phase adjustment mechanism are formed on a single substrate, and an optical branch is provided in the laser output section to send light to a plurality of waveguides. In addition to branching, each independent phase adjustment mechanism adjusts the phase of the propagating light so that the directivity of the emitted light can be changed.

In the present invention, a normal optical waveguide branching technique can be used for branching the laser output section.

Further, the phase adjustment mechanism used in the present invention can adopt any configuration. For example, by flowing a current through the p-n junction of the waveguide and changing the current density, the refractive index changes (as the current density increases, the waveguide (the refractive index of the light guide layer decreases) and the phase of the propagating light changes accordingly. Alternatively, the phase adjustment may be performed by applying an electric field to the waveguide instead of controlling by applying a current.

[Effect]

In the configuration of the present invention, each of the multiple waveguides that branch the laser output has an independent phase adjustment function, so there is no problem with laser control, and the phase adjustment function can be controlled separately, making it easy to control. By changing the phase of the propagating light independently in each waveguide, the directivity of the emitted light can be easily changed.

〔Example〕

FIGS. 1 to 4 are plan views of an embodiment of the present invention, respectively.
A-a' line sectional view, b-b" line sectional view, and C-C'
A line cross-sectional view is shown.

In FIG. 1, a laser oscillation region LD is provided on one substrate 1.
O5C and a waveguide region LDCONT are provided 6.

A distributed feedback laser is formed in the laser oscillation region LDO5C, and the laser stripe is indicated by 2.

In addition, in the waveguide region LDCONT, 3.4 waveguides are formed by branching the laser stripe 2, and the phase adjustment mechanism P instructs the light passing through each waveguide to be 5 or 6.
It is emitted to the outside via CONT. The output light is A.

The length of the branch portion is 100 μm, and the length of the parallel waveguide portion in which the phase adjustment mechanism PCONT is formed is approximately 200 μm.

Next, the a-a' section in Fig. 2 and the bb-b in Fig. 3.
'The cross section is a diagram illustrating a laser oscillation region.

In FIGS. 2 and 3, corrugations (unevenness) 21A are formed in the laser oscillation region on the surface of the n-1nP substrate 21, and the following growth layers are sequentially formed on the corrugations 21A.

2'l ・−n −InGaAsP light guide layer λg=
1.15μm 23-Undoped InGaAsP active layer λg=1.3
μm 24 ・-p −InGaAsP light guide layer 2 μm1.
15μm 25--p-1nP cladding layer 27--p-1nGaAsP contact layer On the other hand, to explain the waveguide region with reference to FIGS. 2 and 4, there is no corrugation (unevenness) on the surface of the InP substrate 21. The following growth layers are sequentially formed on top.

24.-p-InGaAsP light guide layer 2 μm1.
15 μm 25-.-p -1nP cladding layer 26-9-1nGaAsP contact layer When obtaining the above growth layers of the laser oscillation region and waveguide region,
2 on the substrate 21 on which corrugations are partially formed.
A corrugated portion 21A and a corrugated portion 21B are formed by epitaxially growing layers 2 and 23 and exposing the substrate by etching the other surface portions leaving a laser stripe. Thereafter, each of layers 24 to 27 is epitaxially grown.

Next, by etching, the laser stripe 2 and waveguide 3 are left, and the other parts are removed until reaching the substrate 21, and the laser stripe 2 and waveguide 3 are removed as shown in FIGS. 3 and 4. It is embedded with n-1nP32.

Thereafter, the groove 28 shown in FIG. 2 is further formed to electrically isolate the laser oscillation region and the phase adjustment region. Then, an electrode 31 is formed on the back side of the substrate 21, and on the front side, an electrode 29 is formed in the laser oscillation region and an electrode 30 is formed in the waveguide region.

The method for manufacturing the semiconductor light emitting device of this example will be described in detail below.

First, on the n-InP substrate 21, a corrugation with a depth of 400 and a pitch of 2000 was formed with a width of 300 μm.
[After forming in (the portion 21A that will become the laser oscillation region), an n −1nGaAsP light guide layer 22 is formed on the entire substrate surface.
(λg=1.15 μm, thickness 0.1 μm), undoped InGaAsP active layer 23 (λg=1.3 μm, thickness 0
゜1μm), p -1nGaAsP light guide layer 24 (
(λg=1.15 μm, thickness 0.2 μm) are sequentially grown by a liquid phase growth method. After the growth, the part without corrugation (the part 21B that will become the waveguide region) is etched with a sulfuric acid-based etching solution to the substrate surface, and then a p-InGaAsP guide layer 24 (2 μm 1.1
5 μm, thickness 0. Jun), p-1nP 25
(thickness: 2 .mu.m), and a p-1nGaAsP contact layer (.lambda.g=1.2 .mu.m, thickness: 0.3 .mu.m) is grown on the entire surface. After this, using the SiO2 film as a mask, a width of ~2 μm was formed.
Striped waveguides 2, 3 and 4 are formed.

Using the liquid phase growth method while leaving the SiO2 film mask,
A buried waveguide is formed by growing p-InP33 (thickness ~1 μm) and n-In2S3 (thickness ~2 μm). After the crystal growth, the 5i02 film mask is removed and the p-1nGaAsP contact layer and p
- After partially removing the 1nP layer and forming the groove 28, the electrode 29
, 30.31. With the above steps, the semiconductor light emitting device of this example is obtained.

The operation of the device of this example will be explained below.

The light emitted in the laser oscillation region is guided by the light guide layer and propagated to the waveguide region, where it is horizontally branched into two parts, each of which propagates through the waveguide region. Since the waveguide region has a light phase adjustment function, each propagating light is emitted from the output end after undergoing a phase change. Here, since the two emitted lights cause interference, the electric field strength becomes stronger only in a certain direction. In other words, it has directionality. In this embodiment, by changing the current flowing through the phase adjustment region, the phase of the light changes, so the directivity can be changed. For example, in the far-field image shown on the right side of Figure 1, 1. The directivity can be changed like II or III. In this embodiment, when the currents flowing through the phase adjustment mechanisms on the side of the emitted light A and B are made equal, the advances of the wavefronts of A and B become the same, as shown in (2).

In addition, the current flowing through the phase adjustment mechanism 5 on the output light side of A is changed to
If the output light side of 6 is made larger, the refractive index of the A side will be lowered by the amount that the current density is larger than that of the B side, so the output light A of the 5 side will be smaller than the output light B of the 6 side. The wave front advances and becomes like ■. Also, if the current flowing through the phase adjustment mechanism 6 on the outgoing light side of B is made larger than that on the outgoing light side of A, the refractive index on the B side will decrease by the amount that the current density is greater than on the A side. , the wavefront of the emitted light B is more advanced than that of the emitted light A, as shown in (■).

In this manner, the semiconductor light emitting device of this embodiment has the advantage that the directivity of light emitted from the emission end can be intentionally changed.

Note that in the example shown above, the light coming from the laser oscillation region is split into two at the laser output section, but if the light is split into three or more and the phase is adjusted using each waveguide, the directivity can be adjusted more easily. Can be performed with good controllability. Further, in the above embodiment, only the laser output section may be divided into sections, and each section may be provided with a phase adjustment function.

〔Effect of the invention〕

As described above, according to the present invention, the directivity of the emitted light can be easily changed by providing a plurality of waveguides in the laser output section and changing the phase of the propagating light independently in each waveguide. be able to. Further, according to the configuration of the present invention, it is easy to separate the emitted light of 311M1 or more by branching into three or more, and therefore it is possible to control the directivity of the emitted light with high precision. First, it is also possible to control the half-value width (of the far-field image) of the emitted light.

[Brief explanation of the drawing]

FIG. 4 is a sectional view taken along the line c-c' in FIG. 1, and FIG. 5 is a sectional view of the conventional example. 1-...Substrate LDOS C---Laser oscillation area LDCONT-
1. Waveguide area 2 - Laser stripe (waveguide) 3.4 - Waveguide (of waveguide area) 5.6 - Phase adjustment mechanism PCONT A, B - Emitted light← - 1 and 21 - n InP substrate 21A -Corrugation (unevenness) 21B--Surface without corrugation 22-- n
-1nGaAsP light guide layer 23 - undoped InGa
AsP active layer 24 -p -rnGaAsP optical guide layer 25... -p -1nP cladding layer 26-p -1nGaAsP contact layer 27--p
- [nGaAsP contact layer 28 - groove 29.30.31-m-electrode 32-n -1nP 33-・p-1nP

Claims (1)

[Claims] A semiconductor light emitting device including a laser oscillation region and a waveguide region on the same substrate, comprising: a waveguide type optical branch provided in a laser output section of the laser oscillation region, and a laser branched at the branch. What is claimed is: 1. A semiconductor light emitting device comprising: a waveguide that propagates light and has an independent phase adjustment mechanism; and a light output end provided on the waveguide.