JPS63305583A - Integrated wavelength controlling semiconductor laser - Google Patents

Abstract

PURPOSE:To facilitate its manufacturing and to obtain high yield, by separating two resonators by an internal reflection plane so that a length of a larger resonator and that of shorter one are made to be L1 and L2 respectively and next by integrating a plurality of internal reflection interference type semiconductors, which are different in values L1-L2 from each other, on a similar substrate. CONSTITUTION:Two resonators are separated by an internal reflection plane of an internal reflection interference type semiconductor laser so that a length of a longer resonator and that of a shorter one are made to be L1 and L2 respectively. A plurality of the internal reflection interference type semiconductor lasers, which are different in values L1-L2 from each other, are integrated on a similar substrate. Wavelength control can be hence performed, and further an integrated wavelength controlling semiconductor laser, which oscillates at a plurality of arbitrary wavelengths when the values L1-L2 are varied in the order of several mum to tens of mum between adjacent lasers, can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light source for optical communication, and particularly to a semiconductor laser for broadband high-capacity transmission.

2. Description of the Related Art In recent years, there has been a demand for semiconductor lasers that operate in a stable single-longitudinal mode as light sources for long-distance optical communications. Furthermore, a wavelength multiplexing optical communication system has been proposed as one of the large-capacity optical transmission systems that transmits a wide variety of information at once, and integrated wavelength sterilization semiconductor lasers are available as light sources for this purpose. Volume 39, No. 6, P, 521-542 1984
``Integrated Wavelength Controlled Semiconductor Laser'' by Yutaka Nakamatsu et al.

Another threshold is the fi of this conventional integrated wave invasion fighting semiconductor laser.
1 structure, 201 is an n-InP substrate, 20
2 is an n-rnGaAsP optical waveguide layer, 203 is an n-In
Pn covered layer, 204 is InGaAsP active layer, 205
is p-1nP cladding layer, 206 is p-InGaAsP
Cap layer, 2Q7 p-InP layer and 208 n-In
P layer is a current blocking layer, 209 is a p-InGaAsP layer, 2
10 is 5in2.211 is Au/Zn/Au electrode, 21
2 is Au/Ge/Au electrode, 213 is 201n-1nP
This is a diffraction grating formed on a substrate. In this laser, the oscillation wavelength is controlled by the wavelength selectivity of the diffraction grating, and the period of the diffraction grating of one laser is set to 2000, and the period of the diffraction grating of the other laser is set to 20028. As a result, the oscillation wavelength can be varied by about 15 between the two lasers.

Problems to be Solved by the Invention However, in the above-mentioned more t1η formation, it is safe to create a diffraction grating with an extremely fine structure with a period of about 2000 nm adjacent to the active layer for wavelength control. Another problem was that in order to integrate multiple wavelengths, it was necessary to create the period of the diffraction grating between adjacent lasers with high accuracy, such as by several people.

;E1. ．． In view of the above, the object of the present invention is to provide an integrated wavelength-controlled semiconductor laser that is easy to manufacture and has a high yield.

However, in the present invention, the resonator length of one of the two resonators separated by the internal reflection i of the internal reflection interference type semiconductor laser is set to L.
A plurality of internal reflection interference type semiconductor lasers having different values of L and -L2 were integrated on the same substrate, where L2 is the shorter resonator length.

Effect of the present invention By using an internal reflection interference type semiconductor laser as in the above-mentioned configuration, it is possible to control the wave pattern, and the value of -L2 can be varied by several tens of μm from several/1 m between adjacent lasers. By doing so, it is possible to easily create an integrated wavelength-controlled semiconductor laser that oscillates at multiple wavelengths.

Embodiment FIG. 1 is a structural diagram of a two-wavelength integrated wavelength-controlled semiconductor laser in an embodiment of the present invention. This refined laser consists of a first semiconductor laser and a second semiconductor laser. FIG. 2 is a diagram showing the relationship between Ll-L2 and oscillation wavelength in the semiconductor laser shown in FIG. 1.

First, a method for manufacturing the first semiconductor laser will be explained.

FIG. 3 is a cross-sectional view including the active layer seen from the lateral direction and FIG. a1 showing the cavity end face of the fir mode control laser according to the embodiment of the present invention. FIG. 4 shows a top view (FIG. 4a) and a cross-sectional view (FIGS. 4S and 4C) of the groove during the etching process after the first growth.

In FIG. 3, the n-InP substrate 1 is grown by the first growth.
01, an n-1nP buffer layer IQ2 acts as a current blocking layer (p-InP103 and n-InP104, and an n-InGaAsP layer 104 acts as an etching mask layer).
is grown. Next, on the etching mask layer 105, 8
102 is deposited and a window is opened by photoetching in a stripe shape of approximately 1.5 μm width, thereby exposing the etching mask layer 106 in a stripe shape.

Next, a resist stripe with a width of approximately 1 μm is formed perpendicular to the SiO□ stripe by photolithography, and the n-InGaAsP layer 105 is etched using an H2SO4 enchantment using the above S10□ and resist as a mask to form striped windows 5102. and S
A portion of 1n-InGaAsP is left within the iO□ stripe window (FIG. 4a).

When etching is performed using HCe as an etchant using a mask as shown in FIG. 1, the cross-sectional view in the stripe direction of the striped window of 5lo2 becomes as shown in FIG.

After removing the n-InGaAsp 106 within the 51o2 striped window by etching again using H2SO4 enchantment, etching is performed again using HC (j) as an etchant to form a convex portion 112 (FIG. 4C).

After removing the SiO film 116, n I n + x, G ax1 S y, P
1y1 Clad layer 1o6゛n-In=xG&xA
syP, , Active layer 107, p-In, , Gax 2 people 572PI Y2 Krat, 910 B, p-In
n-In with a GaAsP cap layer 109 grown in sequence
, -xGaxAsyPl-y The active layer 107 has the convex portion 11
2 and a position 114 of the n-InGaAsP mask layer. x=0.24. x1=x2=O
, o6.

Y=0.55,7. =72=0.14, the bandgap of the cladding layer is 1.25 (θV), the refractive index is 3.43, and the bandgap of the active layer is 1.3ei (ev
), and the refractive index was set to 3.51. Since the convex portion 112 is a part of the current blocking layer grown by the first growth, its refractive index is 3.40, which is the refractive index of InP. The width of the active layer is approximately 2.2
μm, and the thickness near the center is approximately 0.1671 m.

Ohmic electrodes 110° and 111 were attached to such a wafer.

The second semiconductor laser is manufactured on the same substrate in the same process and at the same time as the first semiconductor laser. After the ohmic electrodes 110 and 111 are formed, the ohmic electrode 110 is etched away using a photoresist as a mask, and then, The seven n-InP pamphlet layers 102 are sequentially applied to the InGaAsP layer using an H2So4 etchant and the InP layer using an HCt etchant.
A separation groove 118 reaching 100 mm was formed between the first semiconductor laser and the second semiconductor laser.

The integrated laser according to the embodiment of the present invention is one in which two internal reflection interference type semiconductor lasers are integrated on the same substrate by the above-described manufacturing method (FIG. 1a).

Each internal reflection interference type semiconductor laser is a double cavity laser separated by an internal reflection region 119 having a width d. The two cavity length beams of the first semiconductor laser are L2,
The second semiconductor laser is L12. It is L12.

d=2/jm, total resonator length (L, +L2+d, L1'+
When L2'-I-d) is 200 .mu.m, the relationship between -L and oscillation wavelength is shown in FIG.

In this example, the first semiconductor laser glue, -L2=
When starting with 6E5μm, the oscillation wavelength becomes 13000 ± 3, and L of the second semiconductor laser, ' -L 2' =
If we set it to 6911m, the height would be 13011±38.

The oscillation threshold of each laser is -30 to 60 m, and most devices exhibit single mode operation at about 1.2 times the threshold, and there is no mode hopping up to about 4 times the threshold. It shows extremely stable single-longitudinal mode oscillation.

In this example, a long wavelength laser using InP/TnGaAsP was described, but a laser using GaAs/(,
It is no secret that a similar effect can be obtained with a laser using aA7AS material.

Effects of the Invention As described above, according to the present invention, by integrating internal reflection interference type semiconductor lasers in which the values of L and -L2 differ by several μm to several μm on the same substrate, the integrated wavelength can be easily changed. A controlled semiconductor laser can be realized, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of an integrated wavelength-controlled semiconductor laser according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between Ll-L2 and the oscillation wavelength, and FIGS. 3a and 3b are diagrams of the semiconductor laser shown in FIG. an end view of the resonator and a cross-sectional view including the active region seen from the side;
4a to 4C are etching process diagrams of the manufacturing process of the same semiconductor laser, and FIG. 5 is a structural diagram of a conventional integrated wavelength control semiconductor laser. 101---...n-I nP substrate, 1Q6...
...n-engine nG2LASF cladding layer, 1oy=...
n-InGaAsP active layer, 10El-...-p-In
GaAsP cladding layer, 112-... Convex portion, 115,
116...End face. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Fig. 2 Good condition, 1 inch, 1 piece of vine, 1 piece of leg racer. l/δ倚11 Nose 2I21 Basket Ll-12 and release 1: a Seki 4 tails (L++12”4-20
0. un) Figure 3//6 Phase 8 4th mouth - InGtaAs P0S

Claims (1)

[Claims] An internal reflection surface is formed by making a part of the active layer have a different refractive index from other parts, and of the two resonators separated by the internal reflection surface, the length of the longer one is L_1, and the length of the shorter one is L_1. 1. An integrated wavelength control semiconductor laser characterized in that a plurality of internal reflection interference type semiconductor lasers having different values of L_1-L_2 are integrated on the same substrate, where the resonator length of is L_2.