JPH0949948A - Array type light emitting element module and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light emitting element module which is reducible in size and capable of outputting laser beams of plural wavelengths combining desired oscillation wavelengths by forming diffraction gratings respectively having specific diffraction wavelengths near the respective incident ends of optical fibers. SOLUTION: This light emitting element module is mainly composed of a light emitting element array 10 and optical fiber array 20 loaded on a substrate 30 and has further a lens array 40 inserted between the light emitting element array 10 and the optical fiber array 20. The diffraction gratings 2a are formed near the incident ends of the respective optical fibers 2 constituting the optical fiber array 20. The diffraction gratings 2a formed at the respective optical fibers 2 of the light emitting element module constituted in such a manner are external resonators to the light emitting elements 1. Accordingly, by adequately setting the diffraction wavelengths at the diffraction gratings 2a, the arbitrary setting of the oscillation wavelengths of the laser beams emitted by every optical fiber 2 is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array type light emitting device module. More specifically, the present invention relates to a structure of a novel light emitting element module capable of simultaneously outputting laser beams of desired plural kinds of oscillation wavelengths.

[0002]

2. Description of the Related Art As a method for realizing higher speed and higher density transmission in data transmission using optical signals, WDM (Wav
elength-Division Multiplexing) method. In this method, the transmission density can be efficiently improved by superimposing and transmitting the optical signals having different wavelengths on one optical transmission line.

When performing the WDM method as described above, it is necessary to use a plurality of laser light sources having different oscillation wavelengths. Therefore, DFB (Distrib
utedFeedBack) laser and DBR (Distributed Bragg Refl)
A plurality of light emitting element modules equipped with lasers and the like are prepared, and laser light emitted from each semiconductor module is combined in an optical combiner to generate transmission light.

However, in the above-mentioned method, the WDM
Designed WD when configuring the light source for the transmission system
There is a problem that it is difficult to align light emitting element modules having a predetermined oscillation wavelength necessary for M transmission. Further, since it is necessary to assemble each light emitting element module and then further combine them, there is a problem that the number of manufacturing steps is large and an increase in cost cannot be avoided.

Further, the conventional WDM light source as described above,
Since the light emitting element modules individually manufactured are combined, it is very difficult to downsize the WDM light source as a final product. On the other hand, a light emitting element module as shown in FIG. 9 in which a plurality of semiconductor lasers and a plurality of optical fibers are integrally combined is already known, mainly for the purpose of high-density mounting and cost reduction. This light emitting element module has a common light emitting element array 10 in which a plurality of light emitting elements 1 are arranged in one row and an optical fiber array 20 in which a plurality of optical fibers 2 are arranged in parallel on one arrangement plane. It is configured by being mounted on the substrate 30. Further, in practice, in this type of light emitting element module, an optical system 40 such as a lens is inserted between the light emitting surface of the light emitting element array 10 and the incident end surface of the optical fiber array 20, and the light emitting element 1 The coupling efficiency with the fiber 2 is improved.

However, in the conventional light emitting device module including the plurality of light emitting devices and the optical fiber as described above, the plurality of light emitting devices 1 included in the light emitting device array 10 have the same emission wavelength and different wavelengths. Cannot be used as a WDM light source that requires the optical signal of. That is, this conventional light emitting device module can only support parallel optical transmission.

[0007]

Therefore, the present invention solves the above-mentioned problems of the prior art and enables miniaturization, and at the same time outputs laser light of a plurality of wavelengths in which desired oscillation wavelengths are combined. It is an object of the present invention to provide a novel light emitting element module that can be used. It is also an object of the present invention to provide such a light emitting device module.

[0008]

According to the present invention, a plurality of light-emitting elements and a plurality of light-emitting elements arranged so as to receive light emitted from the light-emitting elements on one end face thereof, respectively. In an array type light emitting device module including a fiber, an array type light emitting device module characterized in that diffraction gratings each having a specific diffraction wavelength are formed in the vicinity of the incident end of each of the optical fibers. Provided.

As a method of manufacturing an array type light emitting device module according to the present invention, according to the present invention, a step of fixing each of the optical fibers on a predetermined array plane after forming a diffraction grating in advance is provided. A method for manufacturing a light emitting device module is provided, which comprises:

Further, as another method of manufacturing the array type light emitting device module according to the present invention, according to the present invention,
A method for manufacturing a light-emitting element module, comprising: a step of fixing a plurality of optical fibers on a predetermined array plane; and a step of forming diffraction gratings near the ends of the fixed optical fibers, respectively. To be done.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A light emitting element module according to the present invention has a plurality of output optical fibers in which a diffraction grating is formed in the vicinity of an incident end of an optical fiber as an emission port for propagating emitted light of a light emitting element to the outside. The main feature is that laser light having a desired oscillation wavelength can be output for each.

That is, when an optical signal of a plurality of kinds of wavelengths is to be generated in a general array type light emitting element module, a diffraction grating is formed in each semiconductor light emitting element itself to oscillate at a desired wavelength. However, in this method, the refractive index of the material of the portion where the diffraction grating is formed is changed due to the density of carriers injected into the semiconductor light emitting element and the temperature change, and due to variations in the phase of the diffraction grating on the end surface of the light emitting element, Finally, it was difficult to realize a desired combination of oscillation wavelengths with good reproducibility.

On the other hand, in the light emitting device module according to the present invention, a diffraction grating is formed in the vicinity of the incident end of each optical fiber and used as an external resonator of the semiconductor laser, so that a desired wavelength of each optical fiber can be obtained. Laser light can be output. Further, by selecting an appropriate specification when forming the diffraction grating, it becomes possible to manufacture a light emitting element module in which emitted lights of desired wavelengths are combined. This external resonator structure is possible because the reflection spectrum width of the diffraction grating formed in the optical fiber is sufficiently narrower than the gain width of the semiconductor laser.

Here, for forming the diffraction grating, there is a method of changing the refractive index of the optical fiber itself by irradiating the optical fiber with ultraviolet rays or X-rays. in this way,
By controlling the irradiation intensity and irradiation time, a diffraction grating having a desired diffraction wavelength can be formed relatively easily.

In the light emitting device module according to the present invention as described above, since the diffraction grating for determining the oscillation wavelength is formed in the optical fiber in which the change in the refractive index due to external factors is small.
Unlike the case where the diffraction grating is formed on the light emitting element itself, the oscillation wavelength as designed can be easily and surely obtained. Further, the oscillation wavelength of the diffraction grating formed in the optical fiber has a very small temperature dependence of about 0.01 nm / ° C., so that the characteristics of the entire light emitting element module are stable against temperature changes. However, if it is desired to control the oscillation wavelength more strictly, more precise temperature control can be performed by controlling the temperature of the diffraction grating formed in the optical fiber using a Peltier effect element or the like.

Further, the light emitting element module is generally used by changing the driving power of the light emitting element itself to modulate the output optical signal, but such a method has a problem that the modulation speed becomes slow. Therefore, according to a preferred aspect of the present invention, an extremely high-speed modulation speed is realized by generating a steady optical signal from the light emitting element itself and modulating the optical signal by an optical signal modulator separately mounted. .

When the light emitting element module is operated by the above method, it is preferable that the light output itself of the light emitting element module is stable. Therefore, for example, the operating state of the light emitting element is monitored from the optical output of at least one of the plurality of optical fibers, and the Peltier effect element mounted on the diffraction grating portion of each optical fiber is feedback-controlled to stabilize the operating temperature. It is desirable to let

As described above, since it is possible to supply the light emitting element module having a plurality of kinds of oscillation wavelengths in any combination of wavelengths, it is possible to easily construct a system capable of data transmission by wavelength multiplexing. become.

Hereinafter, the light emitting device module according to the present invention will be described in more detail with reference to the drawings. However, the following disclosure is merely an example of the present invention and limits the technical scope of the present invention. Not a thing.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the basic structure of an array type light emitting device module according to the present invention.

As shown in the figure, the structure of this light emitting element module is basically the same as that of the conventional light emitting element module shown in FIG. 5, and each optical fiber 1 forming the optical fiber array 20 is incident. Diffraction grating 2a formed near the edge
The main feature is that it has.

That is, this light emitting device module is provided with the substrate 30.
The light emitting element array 10 and the optical fiber array 20 are mainly mounted on the light emitting element array 10.
Lens array inserted between the lens and the optical fiber array 20
It has 40. The above-mentioned diffraction grating 2a is formed in the vicinity of the incident end of each optical fiber 2 constituting this optical fiber array 20.

In the light emitting element module configured as described above, the diffraction grating 2 formed in each optical fiber 2
a serves as an external resonator for the light emitting element 1. Therefore,
By appropriately setting the diffraction wavelength in this diffraction grating, the oscillation wavelength of the laser light emitted for each optical fiber 2 can be arbitrarily set.

The diffraction grating formed on the optical fiber may be formed in advance before mounting the optical fiber on the substrate, or, as will be described later, processed after mounting the optical fiber on the substrate. It is also possible to form a diffraction grating.

That is, as a method of forming a diffraction grating in an optical fiber, a phase grating method, a method of irradiating X-rays, etc. can be exemplified in addition to the interference method. That is, the interferometry is a method in which a plurality of ultraviolet laser beams having different irradiation angles are simultaneously irradiated to a specific region of the optical fiber to form a periodic refractive index distribution due to mutual interference of the laser beams. In the phase grating method, an ultraviolet laser beam is incident on a phase grating having a desired synchronization, and a plurality of diffracted light interference patterns generated by the phase grating are applied to a specific region of an optical fiber to form a periodic refractive index distribution. Is the way. The X-ray irradiation method is a method of preparing a mask having a refractive index distribution period formed on an X fiber and irradiating the mask with X-rays to form a refractive index distribution on the X fiber. In these methods, it is possible to form a diffraction grating of arbitrary specifications only in a desired region of a desired optical fiber by using a mask in which only a region forming a diffraction grating of a specific optical fiber is exposed. it can.

In the method of irradiating the optical fiber with ultraviolet rays or X-rays, it is possible to easily form diffraction gratings having different diffraction wavelengths by controlling the irradiation intensity and irradiation time. Therefore, after fixing a plurality of optical fibers to the substrate, it becomes possible to form diffraction gratings having different specifications for each optical fiber.

FIG. 2 is a diagram showing a method of forming diffraction gratings having different diffraction wavelengths in the vicinity of the incident end of an optical fiber by irradiating ultraviolet rays having a light intensity distribution with a diffraction grating period for forming the diffraction grating. Is.

In this method, the diffraction grating is formed by irradiating the vicinity of the incident end of the optical fiber 2 with ultraviolet rays. That is, as shown in FIG. 2 (a), by irradiating ultraviolet rays through a filter 100 having a distribution of ultraviolet ray transmission amount,
The intensity of the ultraviolet rays applied to each optical fiber 2 can be changed as shown in FIG. 2 (b). By such a method, since the average irradiation intensity is different for each optical fiber, it is possible to form a diffraction grating having a unique diffraction wavelength.

FIG. 3 is a diagram showing another method of forming diffraction gratings having different diffraction wavelengths on a plurality of optical fibers by irradiation of ultraviolet rays.

In this method, as shown in FIG. 3 (a), the diffraction grating is formed by scanning the regions near the incident ends of the plurality of optical fibers 2 with ultraviolet rays. here,
The scanning speed of ultraviolet rays differs for each optical fiber as shown in FIG. 3 (b), and therefore the average ultraviolet irradiation amount for each optical fiber 2 changes. By such a method, as shown in FIG. 3C, a diffraction grating having an arbitrary diffraction wavelength different for each optical fiber can be formed.

As described above, by forming a diffraction grating having a different diffraction wavelength for each optical fiber, it is possible to emit a laser beam having a unique wavelength from each optical fiber 2. Specifically, the gain width of a general semiconductor laser is about 100 nm, and it can be used if the interval is equal to or larger than the oscillation wavelength width (0.1 nm or less). So, for example, set the gain peak of a semiconductor laser to 1550 nm and
By setting the wavelength interval of the diffracted wavelength in the optical fiber at 1 nm intervals in the band of 50 ± 50 nm, it is possible to output a laser with a maximum of 100 wavelengths. Also, if the gain peak of the semiconductor laser is set to 1310 nm and the oscillation wavelength is set at 1 nm intervals in the band of 1310 ± 10 nm, it is possible to take 100 wavelengths in the same way, but in reality, such a large number of wavelengths is required. If not, the number of wavelengths required may be set in the band close to the peak wavelength of the gain. An ultraviolet laser having a wavelength of 244 to 248 nm can be preferably used as the ultraviolet light with which the optical fiber is irradiated.

FIG. 4 is a diagram showing another example of the structure of the array type light emitting device module according to the present invention.

As shown in the figure, this light emitting element module is characterized in that it further includes an optical multiplexer 50 mounted on the substrate 30 in addition to the light emitting element module shown in FIG. That is, in this light emitting element module, the rear end of the optical fiber array 2 coupled to each light emitting element 10 is coupled to the optical multiplexer 50 mounted on the common substrate 30. The optical multiplexer 50 has a function of multiplexing the lights injected from the optical fiber array 20 and outputting the combined lights to the optical fiber 51 which is an emission port. Therefore, from the optical fiber 51, a plurality of laser lights each having a unique wavelength are superposed and emitted. The light emitting element module having such a configuration can be used alone as a light source for WDM optical communication.

As an optical multiplexer that can be used in the light emitting element module as described above, an optical fiber multiplexer in which the cores of a plurality of optical fibers are brought close to each other until the respective propagating lights interfere with each other, or a Y-shaped Alternatively, a planar waveguide or the like having an X-shaped pattern can be used alone or in combination. In the example shown in FIG. 2, all the light emitted from the light emitting elements on the substrate 30 are combined and output to a single output port. However, for example, two light emitting elements are combined to form a plurality of output ports. It is also possible to configure a light emitting element module having.

FIG. 5 is a diagram showing still another configuration example of the array type light emitting device module according to the present invention.

The light emitting device module shown in the figure is an optical isolator in addition to the light emitting device module shown in FIG.
It is configured by adding 70. That is, in applications such as analog optical transmission in which return light due to reflection on the optical transmission path affects the light emitting element, it is necessary to insert an optical isolator between the light emitting element module and the optical transmission path thereafter. However, when the conventional light emitting element module is used, it is necessary to mount a large number of optical isolators according to the number of light emitting elements, resulting in extremely high cost. On the other hand, in the light emitting device module according to the present invention, as shown in FIG. 3, a single optical isolator 70 may be inserted in the propagation optical path of the optical fiber 51 which is an output port. Therefore,
As a whole, the number of manufacturing steps is reduced and the material cost is also reduced.

FIG. 6 is a diagram showing still another configuration example of the array type light emitting device module according to the present invention.

The light emitting device module shown in the figure is constructed by loading the entire light emitting device module shown in FIG. 2 on a Peltier effect device 60. With such a configuration, the temperature of the entire light emitting element module can be managed extremely accurately. That is, for example, the substrate
A temperature detection element 61 such as a thermistor is mounted on the 30 and a Peltier effect element drive circuit 62 that supplies a drive current to the Peltier effect element 60 while monitoring a change in the output (resistance value in the case of a thermistor) of the temperature detection element. The feedback control makes it possible to control the wavelength characteristics of the light emitted from the light emitting element module extremely accurately. Specifically, since the temperature of the light emitting element module having such a configuration can be controlled up to about 0.01 degree Celsius, the fluctuation of the diffraction wavelength in the diffraction grating having the temperature characteristic of about 0.01 nm / degree is usually 10 ^−4. It can be suppressed to below nm. In this way, it is possible to obtain an output with a very stable wavelength.

FIG. 7 is a diagram showing still another configuration example of the array type light emitting device module according to the present invention. The constituent elements common to those of the light emitting element module shown in FIG. 1 are designated by common reference numerals, and detailed description thereof is omitted.

As shown in the figure, this light emitting device module has the same basic structure as the array type optical device module shown in FIG. 1, and further includes a Peltier effect device 81 for cooling the diffraction grating portion 2a of the optical fiber 2. And this Peltier effect element 81
Its main feature is that it is provided with a Peltier effect element drive circuit 82 for supplying a drive current. Here, the Peltier effect element drive circuit 82 uses the optical fiber 2 with a diffraction grating.
Of the optical fiber 2
The Peltier effect element 81 is configured to perform feedback control by detecting a change in the temperature of the diffraction grating portion 2a from the emitted light. With such a configuration, it becomes possible to automatically compensate for a change in light output due to a change in temperature. Since the control accuracy in such a configuration seems to be about 1 degree, the control accuracy is lower than that in the configuration shown in FIG. On the other hand, there is an advantage that it is not necessary to mount an additional element such as a temperature detecting element on the optical element module.

FIG. 8 is a diagram showing still another configuration example of the array type light emitting device module according to the present invention. The constituent elements common to those of the light emitting element module shown in FIG. 4 are designated by common reference numerals, and detailed description thereof is omitted.

As shown in the figure, this light-emitting element module has an optical modulator 90 having the configuration of the array type optical element module shown in FIG. It is configured by mounting. That is, as described above, when the drive power of the light emitting element 1 itself is changed to modulate the output optical signal, the modulation speed becomes slow. On the other hand, in the case of the above-described configuration, a constant optical signal is generated from the light emitting element itself, and the optical signal is modulated by the separately mounted optical signal modulator 90, thereby improving the modulation speed. be able to.

As the optical signal modulator 90, one using LiNbO ₃ or one using a multiple quantum well structure with GaAs / AlGaAs or InGaAsP / InP semiconductor elements can be specified.

With the above-described structure, while the limit of the modulation speed of the conventional optical element module which does not use the external modulator is 10 GHz or less, the optical modulator which uses the external modulator according to the present invention is used. With element modules, it becomes possible to achieve modulation speeds up to around 100 GHz.

[0045]

As described in detail above, according to the present invention, it is possible to easily and surely provide an array type light emitting device module that emits laser beams of different wavelengths, which are obtained by combining desired wavelengths. become. Therefore, by using this light emitting element module, it is possible to easily and inexpensively realize high-density, high-speed optical transmission of the wavelength division multiplexing method.

Further, in the light emitting device module according to the present invention, as described above, after fixing the optical fiber, the diffraction grating can be formed so as to have a desired combination of oscillation wavelengths. Therefore, for example, a product in which the diffraction grating is not formed may be shipped, and the diffraction grating may be formed so that the user has desired specifications according to the application.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an array type light emitting device module according to the present invention.

FIG. 2 is a diagram for explaining a method of forming a diffraction grating on an optical fiber in the array type light emitting device module according to the present invention.

FIG. 3 is a diagram for explaining another method of forming a diffraction grating on an optical fiber in the array type light emitting device module according to the present invention.

FIG. 4 is a diagram showing another configuration example of the array type light emitting device module according to the present invention.

FIG. 5 is a diagram showing another configuration example of the array type light emitting device module according to the present invention.

FIG. 6 is a diagram showing another configuration example of the array type light emitting device module according to the present invention.

FIG. 7 is a diagram showing another configuration example of the array type light emitting device module according to the present invention.

FIG. 8 is a diagram showing another configuration example of the array type light emitting device module according to the present invention.

FIG. 9 is a diagram showing a configuration of a conventional light emitting element module.

[Explanation of symbols]

1 ... Light emitting element, 2, 61 ... Optical fiber, 10 ... Light emitting element array, 20 ... Optical fiber array, 30 ... Substrate, 40 ... Lens array, 50 ... Optical combination Wave instrument, 60, 80
..Peltier effect elements, 62, 82 ... Peltier effect element drive circuit, 70 ... Optical isolator, 90 ... Modulator, 100 ... Filter

Claims (18)

[Claims] 1. An array type light emitting device comprising a plurality of light emitting devices and a plurality of optical fibers respectively arranged corresponding to the respective light emitting devices so as to receive light emitted from the light emitting devices on one end face thereof. In the module, an array type light emitting device module is characterized in that diffraction gratings each having a specific diffraction wavelength are formed in the vicinity of the incident end of each of the optical fibers. 2. The array-type light emitting device module according to claim 1, wherein the optical fiber includes a plurality of optical fibers arranged in parallel on a specific arrangement plane. 3. The array type light emitting device module according to claim 1 or 2, wherein the diffraction wavelength of the diffraction grating formed in at least one of the optical fibers is equal to that of other optical fibers. A light-emitting element module, which is different from at least one. 4. The light emitting device module according to claim 1, wherein the light emitting device and the vicinity of the incident end of the optical fiber are loaded on a common substrate. Characteristic light emitting element module. 5. The light emitting device module according to claim 1, further comprising an optical system arranged between the light emitting device and an incident end of the optical fiber. Characteristic light emitting element module. 6. The light emitting element module according to claim 5, wherein the optical system is a lens array. 7. The light emitting device module according to claim 1, wherein the light emitting device and / or the optical fiber is loaded on a Peltier effect device. Light emitting element module. 8. The light emitting device module according to claim 7, wherein the optical output from at least one of the optical fibers is monitored, and the Peltier effect device is operated according to the optical output. , Said light emitting element and /
Alternatively, the light-emitting element module is configured to control the temperature of the diffraction grating. 9. The light emitting element module according to claim 1, further comprising an optical multiplexer in which the respective output ends of the optical fibers are coupled. module. 10. The light emitting element module according to claim 9, wherein the optical multiplexer is mounted on a common substrate together with the light emitting element and the optical fiber. 11. The light emitting element module according to claim 9 or 10, further comprising an optical isolator inserted in a propagation optical path on the output side of the optical multiplexer. 12. The light emitting element module according to claim 9, further comprising an optical modulator that modulates the light emitted from the optical multiplexer by an arbitrary signal, and the light emitting element. Each of which is configured to generate a steady light output. 13. A method for manufacturing a light emitting device module according to claim 1, wherein each of the optical fibers has a predetermined diffraction grating after being formed with a predetermined diffraction grating. A method for manufacturing a light-emitting element module, comprising the step of fixing on an array plane. 14. A method of manufacturing a light emitting device module according to claim 1, comprising a step of fixing a plurality of optical fibers on a predetermined array plane, and And a step of forming diffraction gratings near the ends of the fixed optical fiber, respectively. 15. The method according to claim 13 or 14, wherein a mask is used in which only a portion corresponding to a region forming a diffraction grating of a specific optical fiber is opened, and irradiation angles are different from each other through the opening. A method for manufacturing a light-emitting element module, comprising the step of forming a diffraction grating on the optical fiber by simultaneously irradiating the optical fiber with laser light. 16. The manufacturing method according to claim 13 or 14, further comprising the step of irradiating each of the optical fibers with ultraviolet rays or X-rays at different irradiation doses to form the diffraction grating. A method for manufacturing a light emitting device module, comprising: 17. The method for manufacturing a light-emitting element module according to claim 16, wherein the ultraviolet ray or the X-ray is irradiated through a filter means having an attenuation characteristic of a predetermined distribution to irradiate the optical fiber. Is controlled, and a method for manufacturing a light-emitting element module. 18. The method for manufacturing a light emitting device module according to claim 16, further comprising the step of irradiating the optical fiber with the ultraviolet ray or the X-ray while changing a scanning speed. Method for manufacturing element module.