JPS62287683A - Light branching semiconductor laser - Google Patents

Abstract

PURPOSE:To offer a light branching semiconductor laser with many functions applying a semiconductor laser, by combining a circular light waveguide and a linear light waveguide. CONSTITUTION:A basic constitution is one in which four linear light waveguides 104 are made to contact with a circular light waveguide 103. In this case, four kinds of resonator combination are possible for a semiconductor laser 102, that is, two kinds of resonator formed only by the respective linear waveguides 104, and the two kinds of resonator formed by a combination of half of the circular light waveguide 103 and the two linear waveguides 104. In order to operate independently these resonators, an N-type clad layer is eliminated in the vicinity of connecting parts of each light waveguide in the manner in which independent carrier injection into each light waveguide is possible. By controlling in this manner the density of carrier injection into a divided N-side electrode 114, a light signal can be branched in one or both directions out of two directions in a state wherein the light signal coming from outward is amplified and its waveform is shaped.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical branching semiconductor radar for switching optical signals.

[Prior art] Optical communication using optical fibers as transmission paths has advantages such as being able to transmit a large amount of information due to the wide band of optical fibers and being unaffected by induced noise. ,
It is expected that it will be widely used in the future. In this optical communication, a transmitting device converts the information to be sent from an electrical signal to an optical signal, the information is transmitted through an optical fiber, and a receiving device converts the information back into an electrical signal. In this case, the optical signal is nothing more than a transmission means that takes advantage of the extremely small transmission loss of the optical fiber of the transmission line to transmit the signal from one side to the other, and the optical signal is used for active signal processing of optical information. I haven't gotten to the point where I can play a role. If optical switching, optical amplification, and waveform shaping could be achieved without converting optical signals into electrical signals by combining one or several optical elements, it would be extremely effective for diversifying the functions of optical communication systems. .

Conventionally, two types of optical switching methods are known: a mechanical system and an optical waveguide system. The mechanical type switches the optical waveguide by mechanically moving the prism or lens system. on the other hand.

Optical waveguide method is lithium niobate CLxNbOs
An optical waveguide is formed on an electro-optic crystal such as ), and the waveguide of light is switched by turning the voltage on and off.

[Problems to be solved by the invention] However, light switching devices based on these methods have limitations in terms of materials for miniaturization, and cannot be made thin, small, or short.
There is a problem in that the direction of the optical components is opposite to the direction they are aimed at.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical branching semiconductor radar which eliminates the conventional drawbacks and has multiple functions using a thin, small and short semiconductor radar.

[Means for Solving the Problems] According to the present invention, in a semiconductor laser having a branched resonator, two or more resonances can be achieved by a two circular waveguide and a plurality of straight waveguides in contact with this waveguide. Furthermore, the cleaved end face of the linear waveguide constitutes the resonator surface, and the electrodes were formed separately so that carrier injection into the circular waveguide and the linear waveguide function independently. It is characterized by

[Example] Next, two aspects of the present invention will be described in detail. FIG. 1 is a top view of one embodiment of the present invention. FIG. 2 to FIG. 5 are implementation 9 of the present invention.
FIG. 3 is an end view illustrating the manufacturing process. Also, Figures 6 and 7 are respectively.

The stages of FIGS. 3 and 5 are shown in top view.

In this example, p-type InP, which is easy to structure and process, is used.
A substrate 101 is used as a base, or a semiconductor radar 102 having a horn-shaped heterostructure is used.

The basic configuration is a circular waveguide 103 and four straight waveguides 1.
04 is in the shape of touching. In this case, four types of resonator combinations are possible for the semiconductor laser 102. That is, there are two types of resonators that are configured only with two individual linear waveguides 104 and two types of resonators that are configured with a combination of two circular waveguide 1030 halves and two linear waveguides 1040. In order to make each of these resonators function independently,
In the vicinity of the connection of each waveguide, approximately seven of the n-type InP cladding layers are removed. The wider the removed portion 113 of the n-type InP cladding layer 111, the larger the proportion of the saturable absorption portion in the resonator of the semiconductor radar 102, which causes the injection current vs. optical output characteristics to have hysteresis characteristics. , the hysteresis width tends to increase. Regarding this, Japanese Patent Application No. 58-142922 and Japanese Patent Application No. 58-167
No. 798 describes this in detail.

This example is manufactured as follows.

First, in FIG. 2, a p-type InP buffer layer 108 is formed on a p-type 1nP substrate 101 by liquid phase epitaxial growth or vapor phase epitaxial growth. p-type 1nP cladding layer 109. Non-doped InGaA with wavelength 1.3μm composition
sP active layer 110. The n-type InP cladding layer 111 is grown condylarly.

Next, in FIG. 3, as shown in FIG. 6, a ridge-shaped waveguide is formed using photolithography and etching techniques so that the lip-shaped circular waveguide 103 and the four linear waveguides 104 touch at two points. Form a wave path. The width of the ridge at this time is 2 μm, which enables single-transverse mode oscillation. Further, the etching depth is set to just before the p-type InP buffer layer 108. In order to inject electrons into each waveguide independently, the n-type InP cladding layer 111 is removed by etching in the removed portion 113 where each waveguide contacts.

In Figure 4, the entire surface is coated with CVD (Chemical Gueno E-
・D? 30% SiO2 film 112 by
00 is laminated thickly.

In FIG. 5, the S r 02 film is removed by panofur dopanic acid over the entire surface except for the removed portion 113 so as to expose only the n-type InP cladding layer of the ridge waveguide using photolithography and etching techniques again, and as shown in FIG. As shown, the n-side electrode 1 is
As 14, Au-Ge-Nt is deposited and alloyed. In the removal part 113, Au-Ge-N is deposited on the S r 02 film 112.
Although i is deposited, it cannot be alloyed with the semiconductor material and can be easily removed by partial chemical etching. In this way, the n-side electrode 114 divided into six parts is formed.

Next, as shown in Figure 5, the thickness of the entire semiconductor is 150 mm.
After polishing to about .mu.m, Ti--Pt--Au is shear-alloyed as a p-type electrode 115 using a sputtering device, and the wafer manufacturing is completed. In the n-side electrode 114 divided into six parts.

Since all electrons are injected into the active layer 110 from the n-type InP cladding layer 111 on the ridge-shaped waveguide,
There is no need to consider mutual crosstalk between the n-side electrodes.

Next, in order to clearly explain the operation of this optical branching semiconductor laser 102, the n-side electrode 114, which is divided into six parts in FIG. 1, is divided into regions (4) to (F).

When electrons and holes are injected only into regions (C) and (D).

Photons are generated except for the removal part 113, and if the cane in the resonator exceeds the loss as a whole, laser oscillation starts using the first and second arm opening surfaces 116 and 117 as resonator surfaces. In addition, even in the state before Rade oscillation, for example, if light with a wavelength close to the Rade oscillation wavelength is injected from the first arm opening 116 side into the region (C), this will act as a trigger to start Rade oscillation. . At this time, as explained earlier, since the removal section 113 becomes a saturable absorption section, the optical output shows a steep rise at the same time as the laser oscillation, and has an optical amplification factor of 20 dB or more and a waveform shaping function. becomes.

Next, (A), (B), (C), (F)
Consider the case where electrons and holes are injected into the region. In this case, two resonators (A) and (B), (A) and CF), and (C) coexist. if.

This is the result of an optical signal 118 being injected into the region (A) from the outside.

When the optical injection triggers Raded oscillation, whether the optical output signal becomes the optical signal 119 in the (B) region or the optical signal 120 in the (C) region depends on the difference in resonator length and CB). , ((:) depends on the magnitude of the current injection density into the region. If the current injection density into the (B) and (C) regions is about the same, the one with the longer cavity length will be optically quenched. The shorter resonator is activated and takes the key from the longer resonator to oscillate the laser.In this case, the removal unit 1
The presence of 13 causes a steep rise in the optical output, and when the optical output is switched from the off state to the on state,
It also has an optical amplification factor of 20 dB or more and a waveform shaping function.

In the embodiment, the case where the optical signal 118 is large from the region (A) has been described, but it goes without saying that the region where the optical signal is injected is not limited. Furthermore, although a ridge-type InP-based semiconductor laser with a p-type substrate was used as the optical branching semiconductor laser, this is not particularly limited either. Furthermore, in the example, 6
Although the divided n-side electrode 114 is used, as long as it is divided into three or more, the difference in characteristics will hardly be a problem, so it may be arbitrary.

[Effects of the Invention] As described above, the present invention allows a plurality of resonators to coexist within a semiconductor laser by combining an 8-circular waveguide and a linear waveguide. By controlling the carrier injection density to the nine-divided n-side electrode,
After the optical signal from the outside is amplified and further waveform-shaped, the optical signal can be optically branched in one or both of two directions. This makes it possible to split light using a minute semiconductor laser.

[Brief explanation of the drawing]

FIG. 1 is a top view of an embodiment of the present invention, FIGS. 2 to 5 are end views illustrating the method of manufacturing a semiconductor radar of the present invention, and FIGS. 6 and 7 are respectively. FIG. 5 is a top view of the intermediate product at the stage of FIGS. 3 and 5; Note that FIGS. 3 and 5 are end views taken along lines GG and I (-H) in FIGS. 6 and 7, respectively. 101...p-type InP substrate, 102... semiconductor Laser. 103... Circular waveguide, 104... Straight waveguide. 108 - P-type InP buffer layer, 109-p-type In
P cladding layer, 110...non-doped InGaAsP
active layer. 111- n-type InP cladding layer, 112 ・-810
2 membranes. 113...Removal part, 114...N-side electrode, 115...
- N-side electrode, 116... first arm opening surface, 117...
Second crystal opening plane, 118... optical signal, 119... (B
) optical signal from the area, 120... (C) optical signal from the area.

Claims (1)

[Claims] 1. In a semiconductor laser having a branched resonator, two or more resonators are formed by a circular waveguide and a plurality of straight waveguides in contact with the circular waveguide, and An optical branching semiconductor laser characterized in that a cleaved end face of a linear waveguide constitutes a resonator surface. 2. The optical branching semiconductor laser according to claim 1, wherein the electrodes are divided so that carrier injection into the circular waveguide and the plurality of linear waveguides function independently.