JPS62173782A - Optical integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain a small-sized optical integrated circuit which operates with a fine input signal by forming a laser driver of an MESFET and a Schottky diode together with a semiconductor laser on a GaAs substrate. CONSTITUTION:After a P-type GaAs grown layer 2 is grown 3mum or thicker on a GaAs semi-insulating substrate 1, an N-type GaAs current block layer 3, a first clad layer 4, an active layer 5, a second clad layer 6 and a cap layer 7 are sequentially grown by an LPE method. Then, a BTRS type semiconductor laser and the grown layer except the layer 2 for an electrode are removed. Thereafter, Si is doped in the substrate 1 to form active layers 10, 11. After an SiO2 is formed on the end of a laser for wiring, a gate electrode 13, a drain electrode 12, and a source electrode 14 are formed to form an MESFET, and a Schottky electrode 15 and an N-type electrode 16 are formed to form a Schottky diode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical integrated circuit and a device capable of emitting laser light with a minute input signal.

2. Description of the Related Art Conventionally, when driving a semiconductor laser element with a minute input signal, a silicon integrated circuit or a circuit combining discrete elements has been used.

Problems to be Solved by the Invention With the techniques described above, it has been impossible to obtain a continuous laser drive current with rising and falling edges due to the insufficient mobility of silicon and the delay caused by wiring. Therefore, the high-speed modulation properties of semiconductor lasers could not be fully utilized. Furthermore, since this circuit uses a large number of elements, the system becomes large.

Means for Solving the Problems In order to solve the above problems, the optical integrated circuit device of the present invention includes a semiconductor laser and 1. a semiconductor laser on a GaAs semiconductor substrate. The drive circuit is integrated with the drive circuit.

Function: With this configuration, the drive circuit can use GaA, which has high mobility.
Since the device is constructed using S as a material, delays due to circuit elements are reduced, and since all elements including the semiconductor laser are fabricated on the same substrate, the spacing between elements is extremely small, which reduces delays due to wiring. do. At the same time, the system becomes more compact.

Embodiment FIG. 1a is an external view of an optical integrated circuit according to an embodiment of the present invention, and the same figure is a sectional view thereof.

The size of the chip is 10.4×7wj.

In the semiconductor laser, as shown in FIG. 1, a current blocking layer (n-type GaAs) 3 having two ridges is provided on a p-type GaAs layer 2 having mesa stripes. This structure is called a BTR3 type semiconductor laser. With this structure, the AlGaAs active layer 5
It is possible to make the film thinner (0.1 μm or less) and concentrate the current. The characteristics of this semiconductor laser can be changed depending on the thickness of the active layer 6, the A1 composition of the active layer 5, the coating structure (thickness, multilayer coating, asymmetric coating) of the light emitting end face, etc.

The BTR3 type semiconductor laser in the optical integrated circuit fabricated here has the following features: (1) thinning of the active layer 6 and optimum end face coating (Al2O3 film thickness λ/4 on the front surface, Al2O3 film thickness λ/4 on the rear surface);
I (h-35 mackerel, λ = 830 nm, Pout = = 40 m'W (Iop
= 90mA) ultra-high output infrared semiconductor laser.

(2) Active layer 5 (7) Reduced A1 composition, ■th=4
0self, λ=750nm, POut=5mW (I.p=
65mA) visible light semiconductor laser.

FIG. 2 shows the circuitry of the GaAs integrated circuit section that drives this BTR8 type semiconductor laser. MESFETTr
Tr Schmitt key diode D1. D2. D3 and ■S FET T r 6, T r 7. Sig 7 key f'f,? -)'D4°D5. D6
are respectively input signals o and o at ECL level (pulse H
-0, aV at I, -1-3V at LO),! ::7:
This is a circuit that converts the circuit into a double-pull configuration, and is compatible with high-speed logic. Also M E S F E T T
r3. T r 4 and T r 6 constitute a current switching circuit. VIP is the constant current source MES
Apply a bias voltage of FETTrs, and set it to -4, esV when the laser operates at a relatively high output, and -5, 2V when the laser operates at a relatively low output, to avoid wasting power consumption. Splash. The MESFET T r s provides a bias current to the laser, and the current can be changed from 0 to 45 mA depending on the value of IB. If set, the laser output will be linear with respect to the input 0-0.

As shown in FIG. 3a, the method for manufacturing this optical integrated circuit is as follows: First, a layer is formed on a semi-insulating substrate 1 by LPE or MOCVD.
p-type GaAs 2 is grown to a thickness of 3 μm or more using the method.

Thereafter, the layers up to the cap layer 7 are sequentially grown by the LPE method. Next, as shown in FIG. 3, using dry etching or chemical etching, the grown layers other than the BTR3 type semiconductor laser and the p-type GaAs layer 2 for electrode are removed. Then the third
As shown in FIG. C, the removed semi-insulating substrate 1 is doped with SL by ion implantation to form active layers 10.11.

Then, after forming SiO□ on the end face of the wiring laser, a gate electrode and metal wiring are formed, and the optical integrated circuit shown in FIG. 1 is completed.

Next, as an example of the characteristics of this optical integrated circuit, FIG. 4 shows a case where an ultra-high output infrared V-ray laser is integrated. Here, the power supply vss is -5.2V. Bias voltage te, VIB
= -4,4V, VIP = -4,5V (!
: When this happens, the characteristics of the GaAs integrated circuit section will be as shown in Figure A. Therefore, if a sine wave with an amplitude of 1.3V is added to inputs 0-6, the current flowing through the laser will be offset 6.
It becomes a sine wave of 5 mA, amplitude 1a, -r mA, and output laser light P. ut is offset 20 mW
, becomes a sine wave with an amplitude of 1stnW. Here, when vIP is decreased, the gain of the differential amplifier circuit is decreased, as shown in B, and the optical output is decreased. Furthermore, when v is made smaller, the laser bias current becomes like C, and the output waveform is distorted.

The BTR3 type semiconductor laser integrated in the optical integrated circuit device of this example has high efficiency and high reliability, so it
In W's APC operation life test, it operated for over 1000 hours! No change in pressure (from 0, O, V, Vlp) was observed.

Effects of the Invention Since the present invention is a GaAs integrated circuit, it has excellent frequency characteristics and responds to laser output light up to an input signal of 2 GHz. Furthermore, since the laser and drive circuit are integrated on one substrate, it is extremely compact.
Eliminates the need for element wiring, reducing the number of assembly steps. As a result of the above, the present invention can be widely used, for example, as a communication light emitting unit in a LAN or the like, a writing/reading laser unit in an optical disc, a laser light emitting unit in a small CD player, and the like.

In this way, the influence of the present invention on devices using semiconductor lasers is significant.

[Brief explanation of drawings]

FIG. 1a is an external view of an optical integrated circuit according to an embodiment of the present invention, which is a sectional view thereof, FIG. 2 is an equivalent circuit diagram of the optical integrated circuit of the present invention, and FIG. FIG. 2 is a cross-sectional view showing a part of the manufacturing process of the optical integrated circuit of the present invention. FIG. 4 is a characteristic diagram of the optical integrated circuit of the present invention. 1...GaAs semi-insulating substrate, 2...
p-type GaAs growth layer, 3...n-type GaAs current blocking layer, 4...p-type AI GaAs first cladding layer, S...AI GaAs active layer, 6...
...N-type AlGaAs second cladding layer, 7...
...n-type AlGaAs cap layer, 8...n-type electrode, 9...p-type electrode, 10...ME
SFET active layer, 11...Schottky diode active layer, 12.14...drain electrode, source electrode, 13...gate electrode, 16...
- Schottky electrode, 16... river, n-type electrode. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (3)

[Claims] (1) An optical integrated circuit device characterized in that a laser driving circuit section comprising a semiconductor laser light emitting section, a Schottky junction field effect transistor, and a Schottky diode is formed on the same substrate. (2) The semiconductor laser light emitting section includes a current blocking layer, a first cladding layer, an active layer, a second cladding layer, a current blocking layer, a first cladding layer, an active layer, a second
A cladding layer and a cap layer are sequentially formed, and two ridges are provided on the block layer, and the structure has a structure in which current can be injected only through the gap between the two ridges. The optical integrated circuit device according to scope 1. (3) The laser drive circuit section includes an input signal conversion circuit that can convert an ECL level input signal to a desired signal level, a differential amplifier circuit with variable gain, and a bias circuit that can flow a constant current to the laser. An optical integrated circuit device according to claim 1, characterized in that it has the following.