JPS6027197B2 - integrated light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an integrated light source suitable for optical communication systems.

In recent years, the quality of optical semiconductor elements and optical fibers has improved, and the practical use of optical fiber communication systems has progressed rapidly.

When put into practical use, optical wavelength division multiplexing transmission systems are expected to be a system that can communicate large amounts of information at low cost. However, conventional optical wavelength division multiplexing transmission systems use multiple light sources (light emitting diodes, laser diodes, etc.) with different emission wavelengths, and the number of components increases because the light from the light sources is multiplexed by a coupling circuit. In addition, the number of man-hours required to assemble and adjust these components increased, making it difficult to lower the cost of the system and further improve its quality.
SUMMARY OF THE INVENTION An object of the present invention is to provide an integrated light source for eliminating the above-mentioned drawbacks and realizing an inexpensive, high-quality optical wavelength division multiplexing transmission system. According to the present invention, in an integrated light source in which a plurality of light emitting elements including an active region and a bonding layer surrounding the active region and forming a bond are arranged on a substrate.
A group of light emitting elements, wherein the active regions of the light emitting elements are arranged in close proximity so that the light emission direction is in one direction, and the active regions of the light emitting elements are made of a material having a larger energy gap along the one direction. An integrated light source is obtained, characterized in that it includes: Now, for the purpose of the following explanation, let us state the basic requirements for realizing a good light source.

Long life and high efficiency are essential for communication light sources.

In order to produce a long-life light source, it is important to match the lattice constant between the heterojunctions of the compound and the electronic constant between the substrate and the compound. When a difference in lattice constant exists, strain occurs, and this strain causes the generation and propagation of dislocations to become noticeable. In a light-emitting element, the electromagnetic energy of light is large, and dislocations absorb this energy and promote multiplication and propagation, causing rapid deterioration of the element. This phenomenon is particularly noticeable in the case of laser devices. A highly efficient light source is realized with a so-called double heterostructure in which an active region is surrounded by layers with a low refractive index and a large energy gap. In a double heterostructure, light and electrons are trapped in the active region, which has a higher refractive index and a smaller energy gap than surrounding layers, making it possible to generate high-intensity light with low power. Next, the present invention will be explained in detail using the drawings.

Figure 1 shows the first embodiment of the present invention, a is a perspective view,
b is a sectional view. 1, 2, 3 and 4 are first, second, third and fourth light emitting diode elements formed on the surface of the n-type substrate 5, respectively; 6, ? , 8 and 9 are the active regions of the first, second, third and fourth light emitting diode elements, respectively.

Here, the active regions 6, 7, 8 and 9 are p-type and are formed of a compound having the same lattice constant as the lattice constant of the substance forming the substrate 5, and the active regions 6, 7
, 8 and 9 are formed of compounds having successively larger energy gaps in this order. 10 and turtle i are bonding layers of n-type and p-type compounds surrounding active regions 6, 7, 8, and 9, respectively;
Among them, the energy gap is larger than the energy gap of the substrate 6 (maximum), and it is made of a compound having the same lattice constant as the lattice constant of the substrate 6.

12, 13, tortoise 4 and 15' are positive electrodes for driving the first, second, third and fourth light emitting diode elements, respectively, and 16 is a positive electrode for driving the first, second to third light emitting diode elements. It is a common negative electrode.

In this configuration, when a voltage is applied between the positive electrode turtle 2 and the negative electrode 16, light emission occurs in the active region 6 of the double heterostructure light emitting diode element 1.

The wavelength of this light emission is approximately determined by the energy gap value of the active region 6. Since the energy gap between the active regions 7, 8 and 9 is larger than that of the active region 6, the incident wavelength light propagates through the active regions 7, 8 and 9 with almost no loss and exits from the end face of the light emitting diode element 4. Emits light. Next, when a voltage is applied only between the positive electrode 13 and the negative electrode 16, the light of wavelength 2 emitted in the active region 7 propagates through the active regions 8 and 9 without loss, but the active region 6 Since the absorption loss is large, it cannot propagate. Between the positive electrode 14 and the negative electrode 16, or between the positive electrode 15 and the negative electrode 16
Similarly, when a voltage is applied between the active region 9 and the active region 9, the light emitted in the active region 9 or the active region 9 cannot propagate in the direction of the active region 7, but The light can be propagated with almost no loss in the direction of the output end face. In this way, "positive electrode 12, electrode 3,
14 and 16 and the negative electrode 16, high-intensity light emission of four wavelengths and multiplexing from the end face of the light-emitting diode element 4 has been described. However, the present invention is not limited to this; It is clear that multiplexing with any number of emissions is possible. Furthermore, in this example, "the bonding layers 10 and 11 made of a common material were used as the layers surrounding the active regions 6, 7, 8, and 9, but any compound having an energy gap larger than the energy gap of the active region may be used." There is no need for "light emitting diode elements 1, 2, 3"
It goes without saying that separate compound layers may be used.

Furthermore, in this embodiment, the substrate 5 is coated with an n-type material, and the active region 6 is coated with an n-type material.
, 7, 8, and 9, and n-type and p-type compounds were used for layer 0 and layer 1, respectively.
It is clear that compounds of opposite type may also be used.

In this case, a positive voltage is applied to the positive electrodes 2, 3, 14, and 15, and a positive voltage is applied to the negative electrode amount 6. A second embodiment of the present invention will be described using FIG.

A is a perspective view, and b is a sectional view. 2nd trial, 22 ships and 23
25 is a laser diode element formed on a substrate 24;
, 26 and 27 are laser diode elements 21,
22 and 23 active regions.

Here, the active regions 25, 26, and 27 have the same lattice constant as that of the material forming the substrate 24, and are made of a p-type compound with a larger energy gap in the order of the active regions 25, 26, and 27. .28 and 29 are active regions 2
These bonding layers are made of n-type and p-type compounds, respectively, which have an energy gap larger than that of the substances forming materials 5, 26, and 27, and which have the same lattice constant as that of the substrate 24.

Between the bonding layer 28 and the active regions 25, 26, and 27, a plurality of sets of diffraction gratings are provided as reflectors, corresponding to the active regions 25, 26, and 27, with different grating intervals in the direction of light propagation, and the laser diode is Elements 21, 22 and 23
The structure is designed to enable laser oscillation. Reference numerals 30, 3 and 32 are electrodes for applying a positive voltage, and 33 is an electrode for applying a negative voltage.

In the above configuration, when a voltage is applied to the electrodes 30, 31, 32, and 33, laser oscillation occurs in the laser diode elements 21, 22, and 23, and their active regions 25, 2
As in the case of the first embodiment in which the wavelength input light from 6 and 27 is oscillated, the energy gaps of the active regions 25, 26, and 27 are increasing in this order, so that the wavelength input light is oscillated. , propagates through the active regions 26 and 27 without being absorbed, and light propagating toward the active region 25 with a wavelength of 2 is absorbed, but light propagating toward the active region 27 is not absorbed. do.

In this way, from the end face of the laser diode element 23, multiplexed light of wavelengths ^, , ^2, and 3 is obtained. In this embodiment, multiplexing of oscillation light of three wavelengths has been described, but the number of laser diode elements is not limited to three.
It is clear that it is sufficient if there are two or more.

Further, in this embodiment, bonding layers 28 and 29 common to the active regions 25, 26, and 27 are formed, but if the compound has an energy gap larger than that of the active regions, the bonding layers 28 and 29 can be formed in the active regions 25, 26, and 27. A corresponding independent bonding layer may also be provided.

Further, in this embodiment, an n-type substrate 5, an n-type bonding layer 28, a p
Although a type active region and a bonding layer 29 are used, it is of course possible to use a substrate 5, bonding layers 28 and 29, and an active region in which n-type and p-type are reversed.

Furthermore, in this embodiment, the laser diode elements 21, 2
active regions 25, 26 and 2 as reflectors of 2 and 23;
Although a diffraction grating was used between the active regions 25, 26 and 27 and the bonding layer 29, a diffraction grating was used between the active regions 25, 26 and 27 and the bonding layer 29, and a grating-like refractive index change inside the active regions 25, 26 and 27 was used. It is also possible to use a diffraction grating formed by forming.

Above, in the first and second embodiments, the case where a plurality of light emitting elements arranged along the light propagation axis is one set has been described, but when two or more sets of light emitting elements are provided on a substrate, It is clear that it is possible.

Furthermore, in the above embodiment, the multiplexed light is extracted from the end face of the light emitting diode or laser diode, which has a large energy gap in the active region. The multiplexed light may be coupled to other optical elements through the optical waveguide.

Finally, the features of the present invention are that light of different wavelengths can be directly multiplexed without using a multiplex circuit, and multiple light sources are integrated on one substrate. Another object is that it is possible to provide a compact light source with high efficiency and high reliability suitable for an inexpensive and high quality optical wavelength division multiplexing transmission system.

[Brief explanation of the drawing]

1A and 1B are a perspective view and a sectional view of a first embodiment of the invention, and FIGS. 2A and 2B are a perspective view and a sectional view of a second embodiment of the invention, respectively. 1, 2, 3 and 4 are light emitting diode elements, 5 is a substrate, 6
, 7, 8 and 9 are active regions, 10 and 11 are bonding layers, 1
2, turtles 3, 14 and 15 are positive electrodes, 16 is a negative electrode, 21, 22 and 23 are laser diode elements, 2W substrate, 25, 26 and 27 are active regions, 28 and 29 are bonding layers, and 30 , 31, 32 and 33 are electrodes. Figure 1 Figure 1 Figure 2

Claims (1)

[Claims] 1. In an integrated light source in which a plurality of light emitting elements each including an active region and a bonding layer surrounding this region and forming a junction are arranged on a substrate, the active regions of the light emitting elements are located on the same plane. The device is characterized by comprising a group of light emitting elements that are arranged so that their light emitting directions are in the same straight line in close proximity to each other, and the active regions of the light emitting elements are made of a material with a large energy gap along the same straight line direction. integrated light source.