JPS6188231A - Optical bistable circuit - Google Patents

Abstract

PURPOSE:To obtain an optical bistable circuit which operates with a low light trigger by employing a method which amplifies external input trigger light by an optical amplifier and then applies it to a bistable semiconductor laser. CONSTITUTION:The bistable semiconductor laser 1 base hysteresis in its current- light output characteristic and light input-light output characteristic. Then when the input trigger light 200 is made incident from the incidence terminal 120 of the optical amplifier 2 while a proper bias current is applied, it is amplified in an optical amplifier active area 100 and enters a light guide 110. The light guide 110 is coupled optically with the striped active area of the semiconductor laser 1, so amplified input trigger light 200 is supplied to the bistable semiconductor laser 1, which is triggered into the 'on' state. The necessary level of this trigger light 200 may be extremely small because it is amplified by the optical amplifier 2, and therefore the optical bistable circuit which operates with the low trigger input is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical bistable circuit for optical logic circuits and optical storage circuits.

(Prior Art and Problems) Research and development is progressing on various optical circuits that perform signal processing using light. An optical bistable circuit is a basic optical circuit constituting these optical circuits, especially optical logic circuits and optical storage circuits. This is an optical circuit that can provide two stable optical output levels for a given optical input. Conventionally, such an optical bistable circuit has several desirable features, such as having the response speed of a bistable semiconductor laser in which a gain region and a saturable absorption region are arranged in series in the cavity axis direction of a semiconductor laser. There is. However, this bistable semiconductor laser has
The problem was that it required a rather large optical trigger input to trigger it into the on state. %, the unavoidable problem is that when the pulse width of the optical trigger input is reduced in an attempt to use it for high-speed signal processing, the manual trigger level increases rapidly.

(Object of the Invention) An object of the present invention is to provide an optical bistable circuit that can operate with a low optical trigger input.

(Structure of the Invention) According to the present invention, there is provided a bistable semiconductor laser having an amplification region and a saturable absorption region, an optical waveguide optically coupled thereto and installed in parallel, and an optical amplifier coupled to the optical waveguide. A low trigger level composite optical bistable circuit is obtained.

(Operations and Effects of the Invention) In order to reduce the optical trigger level in a bistable semiconductor laser, the present invention employs a method in which an externally input trigger light is amplified by an optical amplifier and then applied to the bistable semiconductor laser. ing. Furthermore, since the applied force is applied via an optical waveguide parallel to the striped active region of the bistable semiconductor laser and optically coupled, stable operation can be expected.

The present invention will be described in detail below with reference to the drawings.

(Example) Fig. 1 is a configuration diagram showing the relative positional relationship between a bistable semiconductor laser and an optical amplifier according to an embodiment of the present invention, Fig. 2 is a perspective view thereof, and Fig. 3 (a) (b). ) and (c) are cross-sectional views, respectively. The bistable semiconductor laser 1 has a striped active region including first and second amplification sections 20 and 30 and an absorption region 10.

The optical amplifier 2 includes an optical waveguide 110 parallel to and close to the active region of the bistable semiconductor laser 1 and an optical amplifier active region 100 connected thereto. With this configuration, the bistable semiconductor laser 1 - Shows hysteresis in optical output characteristics and optical input-optical output characteristics.With an appropriate bias current applied, the input from the input end 120 of the optical amplifier 2 to the input 1-IJ
When optical light 200 is incident, it enters the optical amplifier active region 1.
00 and enters the optical waveguide 110. Optical waveguide 1
10 is optically coupled to the striped active region of the bistable semiconductor laser 1, so that the amplified input trigger light 200 is coupled to the bistable semiconductor laser 1 and turns the bistable semiconductor laser 1 into the "on" state. (The required level of this trigger light 200 is amplified by the optical amplifier 2, so it can be extremely small.

This composite optical stabilizer circuit is manufactured as follows.

First, on an n-type InP substrate 40, an n-IrJP buffer layer 41. Non-doped InGaASP active layer 4
2. The P-inp cladding layer 43 is continuously grown to form a double heterocrystal. Next, a first channel pair 50 and a second channel pair 51 are formed by conventional photolithography and chemical etching. A first channel pair 50 distinguishes the striped active region of the bistable semiconductor laser l from the surrounding region, and a second channel pair 51 distinguishes the optical amplifier active region 100 and the optical waveguide 110 of the optical amplifier 2 from the surrounding region. distinguish.

The channel width of each channel pair is approximately 7 μm.
The width of the mesa sandwiched between these was 1 to 1.5 μm.

The wafer in this state is placed in a liquid phase growth furnace and a P-1np first current block layer 44. Second current blocking layer 45 of n-Ir1P. Buried layer 46 of P-InP, P-J
nQaAsp key? Seven layers 47 are grown successively.

At this time, by appropriately setting the supersaturation degree and growth time of the grown melt, the regions shown in FIGS. In the amplification sections 20 and 30 of the optical amplifier 2 and in the optical amplifier active region 100 of the optical amplifier 2, first and second current blocking layers 44 and 45 are formed with first and second channel pairs 50 and 51. It is possible to prevent any growth from occurring on the top of the mesa. Furthermore, the regions shown in FIG. 3(C), that is, the absorption region 10 of the striped active region of the bistable semiconductor laser 1 and the optical waveguide 11 of the optical amplifier 2
In the part where the mesas 0 are close to each other, as a result of the two being close to each other, the overall width of the mesa formed by both mesas becomes large, so it is not possible to grow the second current blocking layer 45 so as to cover the tops of both mesas. can.

The wafer thus formed was coated with hn-ae-Nr over the entire surface as the n-side electrode 60. Second. 3rd (7)
The first and second P-side electrodes 61 and 62 are made of bistable semiconductors.
are divided in the resonator axis direction, and are formed at positions corresponding to the upper portions of the first and second optical amplification sections 20 and 30, respectively. On the other hand, the third P-side electrode 63 is connected to the optical amplifier 2
The active region 100 is formed at a position corresponding to the upper part of the active region 100.

When 30 mAl and 2 On+A are flowed into the first and second P-side electrodes 61 and 62 of this composite optical bistable circuit, respectively, and the incident quadratic light 210 from one resonator end face 70 of the bistable semiconductor laser 1 is injected. , the optical output 220 from the other resonator end face 71 is at the input trigger light level or about 5
When it was 0F, it was tripped to the "on" state. In this state, 6350 mA is applied to the third PMM other pole, and the input end 12
Input from 0) When IJ Gakko 200 was injected, about 2,
Triggered to "on" state at 5sW. That is,
In the present invention, by integrating the optical amplifier 2, an optical bistable circuit with a low trigger level is realized.

In this embodiment, the portion where the striped active region of the bistable semiconductor laser 1 and the optical waveguide 110 of the optical amplifier 2 are formed close to each other automatically forms n-1n due to the nature of crystal growth.
This overlaps with p, resulting in a region where it is difficult for current to flow.

That is, there is an advantage that the saturable absorption region of the bistable semiconductor laser 1 is automatically formed.

In the above embodiment, the bistable semiconductor laser adopted a buried structure, so the striped active region had a laminated structure formed in a striped shape. However, other structures, such as a planar striped structure, Although the laminated structure is not a striped structure, the optical bistable circuit of the present invention can also be obtained with a structure in which the region into which current is injected is striped, and this current injection region becomes a striped active region.

Further, this also applies to the optical amplifier 2.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a perspective view thereof, and FIG. 3 is a sectional view thereof. In the figure, 1 is a bistable semiconductor laser, 2 is an optical amplifier,
1O is an absorption region, 20.30 is an amplification section, 40 is an InP substrate, 41 is a buffer layer, 42 is an active layer, 43 is a cladding layer, 44.45 is a current block layer, 46 is a buried layer,
47 is a cap layer, 50.51 is a channel pair, 60~
63 is an electrode, 1oo is an active region, and 110 is an optical waveguide. Ma? ? ? Mao 3 figure

Claims (1)

[Claims] A bistable semiconductor laser having a laminated structure including a striped active region, and an optical amplifier that guides trigger light to the bistable semiconductor laser, and the striped active region includes an optical amplification section and an optical absorption region. , comprising at least an electrode above the optical amplifying section for injecting a current into the optical amplifying section, and the optical amplifier is connected to an optical waveguide arranged parallel to the striped active region and optically coupled to the optical waveguide. An optical bistable circuit comprising at least an optical amplifier active region.