JPS58175884A - Multiwavelength integration light source - Google Patents

Abstract

PURPOSE:To simply suppress the intensity deviation of the output of a wave collector as well as to contrive miniaturization and integration of the titled light source by a method wherein the deviation of output intensity of beams of light having different wavelengths is effectively cancelled each other out taking advantage of the loss difference existing between ports of the wave collector. CONSTITUTION:Taking advantage of the fact that both of the deviation in the intensity of output light of a plurality of semiconductor laser 22 having different optical wavelengths obtained by changing the distribution constant of a diffraction lattice 24 and the difference of the optical propagation losses existing between the ports of an optical wave collector 23 are independent on the structure of themselves, the semiconductor laser 22 which outputs beams of light having a high light intensity and the input port of the optical wave collector 23 having a larger loss are optically coupled, and in contrast with this, the semiconductor laser 22 which outputs a beam of light of low output light intensity and the input port of the optical collector 23 of smaller loss are optically coupled. Accordingly, a plurality of semiconductor lasers and the input port of the wave collector can be optically coupled respectively, thereby enabling to collectively suppress the output deviation of each optical wavelength in the output of the wave collector.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an integrated multi-wavelength light source in which output intensity deviation of a plurality of lights having mutually different wavelengths is small.

[Technical background of the invention and its problems]

Wavelength multiplexing technology allows the effective use of optical fibers by changing the center wavelength to λ1. Optical signals emitted from two light sources 1 and 2 with different wavelengths of λ3 are combined by a multiplexer 3, and this is combined into an optical 7 eye 7.
The above wavelength λ! is transmitted through the blue quesol 4 and sent to the demultiplexer 5. , the optical signal is demultiplexed for each λ layer and received by photoreceivers g and r, respectively. Therefore, the wavelength OJ% is 92
It becomes possible to perform two systems of optical signal communication simultaneously using one light beam as a signal propagation medium. When performing such wavelength multiplexed communication, it is desired to multiplex a large number of lights by narrowing the wavelength interval of the light as much as possible from the communication efficiency point of 0, for example, to about 101.

Now, when changing the emission wavelength of a semiconductor light emitting device used as a light source, it has conventionally been generally done by changing its composition. The composition ratio with Ga is 1
There are about 96 changes.

On the other hand, a diffraction grating is formed on a substrate with a uniform composition,
There is a semiconductor radar whose emission wavelength is varied by changing the O lattice constant.

This semiconductor radar is used for @DFI (distributed feedback) and DIR
(distributed optical resonator) technology, for example, as shown in FIG. It has a structure consisting of. The emission wavelength of a semiconductor radar having such a structure is determined only by the size of the unevenness of the diffraction grating 10 without depending on its composition, and has the advantage of high wavelength accuracy. Therefore, it is considered suitable as an integrated wavelength multiplexed light source.

However, when the oscillation mechanism is taken into account, the gain increases dramatically.2 At this time, when the semiconductor radar oscillates, the gain exceeds various losses such as free carrier absorption, scattering loss, reflection loss, etc. It is necessary. In a general GaAjAm semiconductor, the gain coefficient that provides the oscillation complementary value is approximately 3001, and as is clear from the characteristics shown in FIG. OX1018
In the case of cx-5, Rade oscillation light can be obtained in a range of about 100 degrees. Therefore, it is possible to form a light source that multiplexes light of approximately 10 waves with a wavelength interval of 10λ.

However, there is a problem in that the oscillation threshold current values for each wavelength obtained in this way are different as shown in FIG. 4(b), and that when driven with the same current value, there is an output intensity deviation. That is, the wavelengths on the shorter wavelength side are set to λ1. λlazy~λ凰◎
When this happens, there is a problem in that the output intensity of the wavelengths λ and λ6 near the center is high, and the output intensity is low on the wavelength sides at both ends.

This shows a guided waveguide type optical multiplexer in which a leading waveguide 12t is formed by diffusing TI on a crystal substrate 11, the waveguide dimensions are approximately 5 to 10 Jm, the waveguide thickness is 2 to 3 μm, and the waveguide spacing is 50071111. It has a three-dimensional structure and has a total size of about 1 cm square.

However, in the case of such an integrated nine-small-melon multiplexer, there is no problem with conventional multiplexers constructed using individual parts, and the problem of propagating light due to the bending of the optical waveguide. Radiation loss becomes a major problem. This means that each optical propagation loss between the plurality of input ports and the output port is different.

When trying to obtain a compact wavelength multiplexing integrated light source that is integrated in this way, there is a problem of output intensity deviation of light traveling at different wavelengths output by multiple semiconductor radars, as mentioned above, and one multiplexer. There were problems such as different optical propagation losses between the input and output ports.

For this reason, there was a problem in its practicality as a wavelength multiplexed light source used in wavelength multiplexed communication.

[Object of the invention] The present invention has been made in consideration of the above circumstances, and
The purpose is to provide a compact and highly practical multi-wavelength integrated light source that suppresses the output light intensity deviation of wavelength-multiplexed light having different wavelengths to a small value.

[Summary of the invention]

In the present invention, the emission wavelength is varied by changing the distribution constant of the diffraction grating, and the deviation in the output light intensity of nine plurality of semiconductor radars and the difference in optical propagation loss between the optical multiplexers 4-) depend on the structure. A semiconductor radar that outputs light at a wavelength with high output light intensity and an optical multiplexer with high loss input 4-
By optically coupling the semiconductor rades that output light with low output light intensity and the low-loss input of the optical multiplexer, the input of multiple semiconductor rades and the multiplexer can be optically coupled. /-) and optically couple them to each other, thereby comprehensively suppressing the output deviation of each wavelength light in the combined output. [Effects of the Invention] Therefore, according to the present invention, the output intensity deviation of lights of different wavelengths can be suppressed. The loss difference between the four ports of the multiplexer will be explained.

FIG. 6 is a schematic configuration diagram showing the first embodiment, xxF
i A first substrate on which a plurality of semiconductor radars 21a, 21b to 12mt are formed, and 22 represents a ts2 substrate on which an optical multiplexer consisting of an optical waveguide is formed. semiconductor radar jj
m, 21b to 221 are formed, for example, on the GaAj substrate 21 with the same composition, and are Dll type diffraction gratings 24.
They have a structure in which they are simultaneously integrated by providing different emission wavelengths. Each of these semiconductor radars J J a ,
The emission wavelength interval of 2 j b to J J n is the same as the above D
By changing the distribution constant of the IR type diffraction grating 240,
It is set to Oλ. Furthermore, these semiconductor radar 2
J a, J J b ~ J J! 1 are arranged close to each other in parallel with the light oscillation directions aligned. .

On the other hand, the light is output from the optical multiplexer xsFi and its substrate LiNb0°, -1-.

- Therefore, each semiconductor radar 21*, 11b to 21M &
The optical coupling between the and each human power /-) of the Kinpaki 2S is performed as follows. Now, change the wavelength of 1° light to the short wavelength side, λ1. λ3~λl.

Then, these are ranked K111 in descending order of light intensity. On the other hand, the optical multiplexer 2JKTo is ranked in order from the input side, which has a characteristic of large optical propagation loss. Then, the semiconductor radar 22a is arranged according to these rankings.

xzb to zzn and input 4-to are associated with each other to optically couple them. That is, in this case, semiconductor radars that output light with wavelengths λ and λ are provided opposite to the outermost inputs of the optical multiplexer 23, respectively.

Then, inside, the wavelength λ4. A semiconductor radar that outputs light with a wavelength of λT, a semiconductor radar that outputs light with a wavelength of λ$, and a semiconductor radar that outputs a light with a wavelength of λ$ are used.
Yes. Further, here, an example is shown in which the semiconductor radars 22a to 221 and the optical multiplexer 23 are formed on separate substrates, and placed close to each other to perform the above-mentioned optical coupling. Of course, it is also possible to simultaneously integrate and form them on the same substrate.

Thus, according to the multi-wavelength integrated light source configured in this way, each semiconductor radar 21m, 2
The output lights 2b to Jjn, which have different wavelengths, are respectively input from inputs (/-) with different loss characteristics and are multiplexed into K. Moreover, a large loss is given to the wavelength light having high output intensity. Therefore, the light intensity of each wavelength in the multiplexed output is averaged, and the intensity deviation is effectively suppressed.

Therefore, there is a concept that when attempting to integrate a light source in wavelength multiplexed communication, it is sufficient to change the current applied to the semiconductor radar O or adjust the temperature. However, since the dimensions of the integrated light source as described above are very small, the -K
Therefore, it is extremely difficult to perform the above control. Even if such control were possible, the 'Q'po control mechanism would be very complicated, and for example, a slight change in current would appear as a change in temperature. However, in order to perform this kind of control, special measures are required, and the advantages of an integrated and miniaturized multi-wavelength integrated light source will be lost. The optical coupling relationship between the semiconductor radar and the input of the multiplexer (/-) is determined by the output intensity and the input l-
It can be said that it is extremely advantageous to define this in correspondence with the loss characteristics of the target.

Now, Figure 7 is a diagram showing another embodiment of the present invention, and is a diagram showing an example in which the multiplexer 26 is constructed using a diffraction grating 2r. In this case, the input side, which is farther from the output 4, passes through the diffraction grating 2r more times, and as a result, the loss increases.
Optical coupling may be effected by arranging the emission wavelengths of the input ports having the highest output intensity to face the input ports that are farthest from the output (-).

Needless to say, even in this case, the same effects as in the above-mentioned embodiment can be achieved.

As described above, according to the present invention, light having a specific wavelength is oscillated and output from a plurality of semiconductor radars integrated simultaneously, and the intensity deviation is suppressed and the light is combined, thereby producing a great practical effect.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the wavelength interval of a plurality of lights, the number of wavelengths, etc. may be determined according to specifications. Further, a semiconductor radar can be constructed using a DPI type diffraction grating instead of a DBR type diffraction grating. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawings] Figure 1 is a schematic diagram of a wavelength division multiplexing communication system, and Figure 2 is a schematic diagram of a wavelength division multiplexing communication system.
Figure 3 shows the change in band width depending on the composition of the Ga-mu semiconductor lede, Figure 3 shows the DPI type cow-shaped conductor lede structure, and Figures 4 (a) and (b) show the gain characteristics and output intensity of the AzGaAa semiconductor lede. FIG. 5 shows an example of an optical waveguide type multiplexer 23... optical multiplexer, 24...
・DIRfi diffraction grating, 25... Raw wave path, 2e...
Optical multiplexer, 21...diffraction grating. Applicant: Director of the Agency of Industrial Science and Technology, Kei Ishizaka - Figure 4, Figure 5

Claims (1)

[Scope of Claims] (1) One O semiconductor radar of the same composition formed by simultaneous integration on a substrate with mutually different oscillation wavelengths;
an optical multiplexer that is integrally formed on a substrate and multiplexes light having different oscillation wavelengths output from each of the semiconductor rades, and the output of each semiconductor rader is determined by the order of the semiconductor rades. At the same time, the order of the inputs 4-) of the optical multiplexer is determined by each person's power 4-. fI# is set in descending order of the optical propagation loss between the output mate and the optical multiplexer, and between the l semiconductor radars and the input ports of the optical multiplexer according to the nine set orders. A first line length integrated light source characterized by being optically coupled in correspondence. (Oi) The semiconductor radar is integrated and the nine substrates and the optical multiplexer are integrated. Claim lIg1 which is made through
Multi-wavelength integrated light source as described in Section 1. (3) The substrate integrated with semiconductor sheets and the substrate integrated with optical waveguides are two separate substrates placed close to each other.The optical coupling between the semiconductor radar and the optical multiplexer is as follows. Opposed optical input/output of the above two separate boards/-)
The multi-wavelength integrated light source according to claim 1, wherein the multi-wavelength integrated light source is transmitted through a light propagation path formed between them. (4) The multi-wavelength integrated light source according to claim 1, wherein the optical multiplexer has a nine-structure structure with a diffraction grating formed on the substrate. (5) The optical multiplexer is made of TI on the LiNbO3 crystal main board.
2. The multi-wavelength integrated device according to claim 1, wherein the multi-wavelength integrated device has a structure in which a leading wave path is formed by selectively diffusing the .