JPS63173381A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To make it possible to switch a wavelength by an external signal and to radiate, from both end-surfaces, laser lights whose wavelengths are different from each other, by a method wherein the change-over of oscillation wavelength is performed by pumping a quantum well laser capable of switching wavelength with the other laser light. CONSTITUTION:When a constant bias current is made to flow through a laser A, a quantum well laser, it radiates a laser light with a longer wavelength lambda1 which can be oscillated. Then a laser B is made to oscillate by supplying a current, and the laser A subjected to a pumping of a laser light 7. When the intensity of the laser light 7 exceeds a specified value, the laser A is subjected to a light-pumping by the laser light 7 as well as a pumping by bias current injection, so that the gain is increased to generate a light of short wavelength lambda2. Thus the wavelength of the laser light generated by the laser A can be switched between lambda1, and lambda2, by changing the current supplied to the laser B. In the case where the same substrate is used, the manufacture is facilitated by a method wherein the laser A and the laser B are so cut off by dry etching that the length of a resonator of the laser A is made short.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a single laser diode by integrating two or more semiconductor lasers.
This invention relates to a semiconductor laser device that takes various oscillation states with one input signal.

[Conventional technology]

The specification of the earlier application relating to the invention of the present inventors (Japanese Patent Application No. 61-1
75967) is capable of switching the oscillation of quantum levels n=l and n=2 formed in the active layer by the amount of current injected into the laser.

[Problem that the invention seeks to solve]

However, in conventional wavelength switching lasers, in order to switch the wavelength, the current injected into the laser must be controlled, and switching cannot be performed using other external signals. Further, there are problems in that only light of the same wavelength can be emitted from both end faces of the laser, which limits the range of use.

This invention was made to solve the above-mentioned problems, and it is possible to switch the wavelength using an external signal, and
It is an object of the present invention to obtain a semiconductor laser device that can also emit laser beams of different wavelengths from both end faces.

[Means for solving problems]

A semiconductor laser device according to the present invention includes a semiconductor laser element that emits laser light of a single wavelength or a plurality of wavelengths, and a position where the emitted light of the semiconductor laser element is located near at least one of the front end face and the rear end face of the semiconductor laser element. The device includes a quantum well laser that is installed so as to be incident on the active layer and is capable of emitting laser beams of two or more wavelengths.

[Effect]

A semiconductor laser device according to the present invention includes a semiconductor laser element that emits laser light of a single wavelength or a plurality of wavelengths; Since the configuration includes a quantum well laser that is installed so as to be incident on the layer and is capable of emitting laser beams of two or more wavelengths, the quantum well laser is optically pumped by the semiconductor laser element, and its pumping intensity is The oscillation wavelength can be changed depending on the

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a diagram showing the configuration of a semiconductor laser device according to an embodiment of the present invention.
-A quantum well laser capable of switching the oscillation wavelength as described in No. 175967, Laser B is a laser that oscillates only one light like a normal laser, 1 is an electrode, 2
is a p-AβGaAs cladding layer, 3 is a quantum well active layer,
3' is generally the same active layer as 3 (but may be different from 3), 4 is n-AjIC; aAs cladding layer, 5 is n
-GaAs substrate; 6 is a lead wire; This chip is bonded to a heat sink and grounded.

Further, 7 is a laser beam emitted from the laser B, and its intensity is controlled by the amount of current flowing through the laser B. 8
is the laser light emitted from laser A.

Moreover, FIG. 3 is used as the laser A mentioned above.

For example, FIG. 4 is a block diagram showing a quantum well laser whose oscillation wavelength can be switched, as described in Japanese Patent Application No. 175967/1982, and FIG. 4 is a cross-sectional view taken along line AA in FIG. In the figure, 10 is an upper electrode, 12 is a 5in2 current blocking layer, and 13 is a p
-QaAs contact layer, 14 is p-A/! GaAs cladding layer, 15 p-AnAs-GaAs superlattice graded index waveguide layer, 16 100
human GaAs active layer, 17 is n-A#As-GaAs superlattice graded index waveguide layer, 1
8 is n-Ajl! GaAs cladding layer, 19 is n-Ga
An As substrate, 20 is a lower electrode, and 11 is a Zn diffusion part (shaded part).

Further, as shown in FIG. 4, the edges of the active layer stripes are somewhat uneven.

Further, FIG. 5 is a diagram showing the energy band structure in the active layer of this quantum well laser, and the curved portion is a portion where the energy band changes parabolically due to the GRIN-3CH structure.

As mentioned above, this quantum well laser has a GRI rl-3CH structure by providing superlattice graded insode wave guide layers 15 and 17 between the upper and lower cladding layers of the active layer, and confines light in the thickness direction. doing. Furthermore, the band gap between the upper and lower cladding layers is sufficiently high, and the layer thickness of the active layer 16 is formed sufficiently thin by 100 layers, so that the active layer 16 forms a quantum well structure, and the active layer 16 forms a quantum well structure. The carriers injected at have a quantized energy band. Furthermore, since the Zn diffusion region 11 has a high band gap and a low refractive index, the carriers in the active layer and the generated light are confined laterally within the width W in the figure where Zn is not diffused.

When carriers are injected into the quantum well laser configured as described above, electrons and holes transition between quantum levels in the active layer 16 according to the number of injected carriers, and reach their respective quantum heavy positions. Generates light of the corresponding wavelength. Then, when the gain due to the current becomes larger than the resonator loss, laser oscillation occurs.

As shown in FIG. 4, the active layer stripe has irregularities, so the generated light is largely scattered at this portion, resulting in loss inside the resonator. Furthermore, by narrowing the stripe width, the resonator internal loss also increases. Now, if we set this stripe width to about 4μ and sufficiently increase the internal loss of the resonator, while the number of injected electrons and balls is small, that is, while the injected current is small, the inside of the active layer shown in Fig. At the transition of quantum weight position n=l, n
Laser oscillation with a wavelength λ corresponding to the Keiko quasi-position of =1 occurs, and light of λ1 is emitted. However, if the injection current is increased, n
The density of states of the carrier at the quantum gravity position of =2 is n = 1
Since it is larger than that at the quantum gravity position, the gain is n=2
The light due to the transition becomes larger and emits light with a wavelength λ2 corresponding to the quantum gravity position of n=2. This allows n=1
However, by setting the magnitude of the resonator internal loss to a predetermined value and flowing a predetermined current, it is possible to simultaneously emit the light of λ1 and λ2.

Next, the operation of this embodiment shown in FIG. 1 will be explained.

Laser A is a quantum well laser that operates as described above.
When a constant bias current is applied in advance to the laser A, the laser A first emits a laser beam having the longer wavelength λ1 among the lights that can be oscillated.

Next, in this state, a current is applied to the laser B to cause laser oscillation, and the laser A is bombed with the laser beam 7. When the intensity of the laser beam 7 exceeds a certain level, the laser A performs optical pumping by the laser beam 7 in addition to the bombing by the bias current injection, so that the gain increases and emits light λ2 with a short wavelength.

By changing the current flowing through laser B in this way, the wavelength of the laser light emitted by laser A can be switched between λ and λ2.

For example, when manufacturing the semiconductor laser device of this embodiment using the same wafer, lasers A and B are formed by dry etching to change the cavity lengths of lasers A and B (to shorten the cavity length of laser A). It can be easily manufactured by cutting B.

Note that in the above embodiment, laser A was set in advance to emit light of λ1, but if it was left in a non-oscillating state, the amount of current flowing through laser B would change to non-oscillating state 2 λ
Three states are obtained: a state that produces 1 and a state that produces λ2.

Furthermore, as described in Japanese Patent Application No. 61-175967, the laser A has a wavelength of λ1. Since λ2 can be produced at the same time, four states can be obtained by adding them.

In addition, in the above embodiment, a wavelength-switchable quantum well laser was installed only on one side of laser B, but since laser B also emits laser light from the rear, a wavelength-switchable quantum well laser is installed on only one side of laser B. If we install Laser C, which is a well laser, at the rear, and set the threshold for changing the wavelength to be different from Laser A, for example by using different bias currents, we can control the wavelengths emitted from the left and right sides.
More various states can be obtained with one chip.

Furthermore, if laser B is also a quantum well laser whose wavelength can be switched by injection current, more various states can be expected.

〔Effect of the invention〕

As described above, according to the present invention, the wavelength-switchable quantum well laser is configured to switch the oscillation wavelength by optically bombing it with another laser. This has the effect of allowing various oscillation states to be taken. That is, this has the effect of providing the possibility of becoming a basic component of future optical logic integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a semiconductor laser device according to one embodiment of the invention, FIG. 2 is a block diagram showing a semiconductor laser device according to another embodiment of the invention, and FIG. 3 is a quantum well laser used in the invention. A configuration diagram showing an example of the configuration, Fig. 4 is A of Fig. 3.
-A cross section, and FIG. 5 is a diagram showing the energy band structure of the laser of FIG. 3. 1 is an electrode, 2 is p-Aj! GaAs cladding layer, 3 quantum well active layer, 4 n-AβGaAs cladding layer, 5 n-GaAs substrate, 6 lead wire, 7 light emitted from laser B, 8 light emitted from laser A, 8' Output light of laser C.

Claims (3)

[Claims] (1) A semiconductor laser element that emits laser light of a single wavelength or a plurality of wavelengths, and the emitted light of the semiconductor laser element enters an active layer near at least one of the front end face or the rear end face of the semiconductor laser element. What is claimed is: 1. A semiconductor laser device comprising: a quantum well laser which can emit laser light of two or more wavelengths; (2) The semiconductor laser device according to claim 1, wherein the semiconductor laser element and the quantum well laser are formed on the same substrate. (3) The quantum well laser is provided near both end faces of the semiconductor laser device, and the threshold values of the two quantum well lasers are different from each other. Semiconductor laser equipment.