JP2000208869A - Light emitting device module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device module which is excellent in high- frequency characteristics. SOLUTION: A light emitting device module 10 is composed of a semiconductor light emitting device 12 and a diffractive grating built-in fiber 14 both housed in a housing 11. Diffraction gratings 13 are formed inside the fiber 14 at positions backward apart from the tip 14a of the fiber 14, and the reflectance of the diffraction grating 13 is set at 70%. The diffraction grating built-in fiber 14 provided with a tip 14a is arranged so as to make its tip 14a confront the fiber-side edge face 12a of the semiconductor light emitting device 12, and a gap between the fiber-side edge face 12a of the light emitting device 12 and the diffraction grating 13 is set 13 mm or below. By this constitution, an optical resonance occurs between the projection-side edge face 12a of the semiconductor light emitting device 12 and the diffraction grating 13 of the diffraction grating built-in fiber 14, and a laser beam is projected from the projection-side edge face 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device module including an optical fiber having a built-in diffraction grating and a light emitting device.

[0002]

2. Description of the Related Art A light-emitting element module in which an end of an optical fiber having a diffraction grating inside is arranged to face one end face of a light-emitting element has a relatively stable spectrum with a simple structure. It is used.

In such a light emitting element module, the other end face of the light emitting element and the diffraction grating in the optical fiber constitute a Bragg reflector type resonator. Is oscillated, and this light is output as output light of the light emitting element module.

[0004] In particular, for example, JJPan, XLJing, Y. Shi: "Fi
ber grating stabilized laser source for dense WDM
systems ", OFC '97 Tech. Dig., p213, the light emitting element module that emits laser light from the other end face side can have a relatively high reflectance of the diffraction grating. , It is possible to obtain a large light output.

[0005]

However, the above-mentioned light emitting element module has the following problems. That is, in the light-emitting element module, since the distance between the one end face of the light-emitting element and the diffraction grating is large (because two collimator lenses are interposed), the distance between the other end face of the light-emitting element and the diffraction grating is small. The interval, that is, the resonator length increases. Therefore, when high-speed modulation is performed using the above-described light emitting element module, the generation of laser light cannot follow the increase or decrease of carriers generated in the laser medium, and a chirping phenomenon that causes severe overshoot and undershoot in laser output occurs. As a result, the high frequency characteristics deteriorate.

Accordingly, the present invention solves the above problems,
It is an object of the present invention to provide a light-emitting element module having less chirping phenomenon and excellent high-frequency characteristics.

[0007]

In order to solve the above problems, a light emitting element module according to the present invention comprises a waveguide formed on a substrate and first and second waveguides each including an end of the waveguide.
And a first optical fiber having a built-in diffraction grating, one end of which is arranged to face the first end surface of the light emitting element, and the reflectance of the diffraction grating is 60% or more, the distance between the first end face of the light emitting element and the diffraction grating is 13 mm or less, and optical resonance is generated between the second end face and the diffraction grating via the waveguide of the light emitting element; The laser light is emitted from the second end face.

[0008] By employing a configuration in which optical resonance is generated between the second end face and the diffraction grating to emit laser light from the second end face, the reflectance of the diffraction grating can be increased. In addition, by setting the reflectance of the diffraction grating to 60% or more, the proportion of light that re-enters the light-emitting element out of light incident on the diffraction grating can be increased. Furthermore, by setting the distance between the first end face of the light emitting element and the diffraction grating to be 13 mm or less, the generation of laser light can follow the increase and decrease of carriers even when high-speed modulation is performed. In particular, the value of 13 mm is a necessary and sufficient value when outputting a signal in the 1.25 GHz band.

In the light emitting device module according to the present invention, the first optical fiber and the light emitting device may be fixed to the same base.

[0010] By fixing the first optical fiber and the light emitting element to the same base, positioning of the first optical fiber and the light emitting element becomes easy.

[0011] The light emitting element module of the present invention may be further characterized by further comprising cooling means for cooling the first optical fiber and the light emitting element.

The provision of the cooling means makes it possible to control the temperatures of the first optical fiber and the light emitting element.

Further, in the light emitting device module of the present invention, a dielectric multilayer film is formed on the second end face,
May have a reflectance of 30% or less.

By setting the reflectivity of the second end face to 30% or less, it becomes possible to increase the ratio of laser light emitted from the second end face.

Further, in the light emitting element module according to the present invention, one end of the first optical fiber may be processed into a spherical shape.

By processing one end of the first optical fiber into a spherical shape, light emitted from the first end face of the light emitting element can be condensed and introduced into the first optical fiber.
Light emitted from one end of the first optical fiber can be collected and made incident on the first end face of the light emitting element.

In the light emitting element module according to the present invention, the other end of the first optical fiber may be cut obliquely with respect to the optical axis.

By cutting the other end of the first optical fiber obliquely with respect to the optical axis, unnecessary reflected light at the other end satisfies the condition of total reflection in the first optical fiber. And disappear.

Further, the light emitting element module of the present invention may be characterized in that the light emitting element module further includes a light receiving element arranged to face the other end of the first optical fiber.

By providing the light receiving element, the output light amount of the light emitting element module can be detected. Therefore,
The output light quantity can be controlled based on the light quantity detected by the light receiving element.

Further, the light emitting element module of the present invention is arranged such that one end thereof is opposed to the second end face of the light emitting element and guides the laser light emitted from the second end face. An optical fiber may be further provided.

The provision of the second optical fiber allows the laser light emitted from the second end face to be efficiently propagated to other optical members and the like.

In the light emitting device module of the present invention,
One end of the second optical fiber may be processed into a spherical shape.

By processing one end of the second optical fiber into a spherical shape, light emitted from the second end face of the light emitting element can be condensed and introduced into the second optical fiber.

In the light emitting device module of the present invention,
An optical isolator is provided between the second end face of the light emitting element and one end of the second optical fiber for selectively transmitting light traveling in a direction from the second end face to one end. It may be characterized in that.

By providing the above optical isolator, the second
The light reflected at one end of the optical fiber and the light propagating through the second optical fiber toward the light emitting element do not enter the second end face of the light emitting element.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A light emitting device module according to an embodiment of the present invention will be described with reference to the drawings. First,
The configuration of the light emitting element module according to the embodiment will be described. FIG. 1 is a sectional view of a light emitting element module according to the present embodiment.

Light emitting element module 10 according to this embodiment
Is an optical fiber in which a semiconductor light emitting element 12 (light emitting element) and a diffraction grating 13 are built in a housing 11 (first optical fiber).
Optical fiber. Hereinafter, it is referred to as a diffraction grating built-in fiber 14).

The housing 11 is formed of Kovar, and is configured by connecting a rectangular parallelepiped main body 16 and a cylindrical tubular portion 18. Inside the housing 11, a semiconductor light emitting element 12 contained therein is contained.
In order to prevent deterioration of other components, an inert gas (for example, nitrogen gas) is sealed. A plurality of external leads (not shown) are provided on both sides of the main body 16 of the housing 11 for supplying a drive current to the semiconductor light emitting element 12 and extracting a light receiving signal of a photodiode described later. Have been.

As shown in FIG. 2, which is a partially enlarged sectional view, the semiconductor light emitting element 12 is formed on a substrate 20 made of InP.
A lower clad layer 22 made of InP, an active layer 24 made of InGaAsP, and an upper clad layer 26 made of InP are sequentially laminated. Semiconductor light emitting element 12
Generates a stimulated emission by supplying a drive current to the active layer 24 to form a population inversion, and the active layer 24 functions as a waveguide for the stimulated emission. One end face (first end face) of both end faces including each end of the active layer 24.
A low-reflection film 28 made of a dielectric multilayer film that makes the reflectance of the fiber-side end face 12a about 0.1% is formed on the fiber-side end face 12a, and the other end face (second end face). In the following, the low-reflection film 30 made of a dielectric multilayer film is formed on the emission-side end surface 12b so that the reflectance of the emission-side end surface 12b is about 30%.

As shown in FIG. 1, the semiconductor light emitting element 14 is mounted and fixed on a heat sink 34 made of copper, and the heat sink 34 is mounted and fixed on a chip carrier 36 which is a pedestal. The chip carrier 36 is fixed on a flat plate portion 38a of a base 38 including a flat plate portion 38a and two upright portions 38b and 38c.

As shown in FIG. 2, the fiber 14 with a built-in diffraction grating is an optical fiber cut into a short length, and one end (hereinafter, referred to as a tip 14a) is polished into a spherical shape and the other end is polished. End (hereinafter, referred to as rear end 14b)
Is cut obliquely to the optical axis. Further, a low-reflection film (not shown) made of a dielectric multilayer film having a reflectance of about 0.1% at the front end portion 14a or the rear end portion 14b is formed on the front end portion 14a and the rear end portion 14b. ing.

The tip 14a of the fiber 14 with a built-in diffraction grating
A plurality of diffraction gratings 13 are formed at predetermined intervals inside a position (particularly, a core portion) receded from the surface, and function as a kind of reflecting mirror. Here, when it is desired to selectively reflect light having a predetermined wavelength λ by the diffraction grating 13, the refractive index of the core of the fiber 14 with a built-in diffraction grating is defined as n, and the distance d between the diffraction gratings 13 satisfies the expression (1). Should be determined.

2nd = mλ (m is an arbitrary integer) (1) The reflectance of the diffraction grating 13 under the above-mentioned predetermined wavelength is 7
It is 0%. The reflectance of the diffraction grating 13 can be easily adjusted by, for example, changing the number of grating layers and the difference in refractive index.

As shown in FIG. 1, the fiber 14 with a built-in diffraction grating is inserted into a ferrule 40, and the ferrule 40 is inserted into an insertion hole (not shown) provided in one upright portion 38 b of the base 38. It is inserted and fixed. On this occasion,
The tip 14a of the fiber 14 with a built-in diffraction grating faces the fiber-side end face 12a of the semiconductor light emitting element 12, more specifically, faces the portion of the fiber-side end face 12a corresponding to the end of the active layer 24. Next, the positioning of the diffraction grating built-in fiber 14 and the semiconductor light emitting element 12 is performed. The fiber-side end surface 1 of the semiconductor light emitting element 12
The distance D (see FIG. 2) between 2a and the diffraction grating 13 is 13 mm
It is as follows.

With such a configuration, the light emitting element module 10 is connected between the output side end face 12b of the semiconductor light emitting element 12 and the diffraction grating 13 of the diffraction grating built-in fiber 14 via the active layer 24 of the semiconductor light emitting element 12. Then, optical resonance is generated, and laser light is emitted from the emission side end face 12b.

A Peltier element 42 (cooling means) is provided below the base 38 so that the semiconductor light emitting element 12 and the fiber 14 with a built-in diffraction grating can be cooled via the base 38 and the like. A thermistor 44 for detecting a temperature is mounted on the chip carrier 36,
Based on the output of the thermistor 44, the Peltier element 42
Temperature control.

Rear end 14b of fiber 14 with built-in diffraction grating
A photodiode 46 (light receiving element) for detecting the intensity of light transmitted through the diffraction grating 13 of the fiber 14 with a built-in diffraction grating is fixed to the support member 48 at a position facing the support member 48. By feeding back the intensity of light detected by the photodiode 46 to the drive current of the semiconductor light emitting element 12, the intensity of light emitted from the light emitting element module 10 can be made constant.

An opening (not shown) is provided in the upright portion 38c provided on the base 38 at a position facing the emission side end surface 12b of the semiconductor light emitting element 12, and the opening is provided with a lens. The lens 52 housed in the holder 50 is inserted.

An airtight sealing window 54 made of a translucent material is formed on the wall surface of the main body 16 constituting the housing 11 and on the optical axis connecting the semiconductor light emitting element 12 and the lens 52.

The cylindrical portion 18 constituting the housing 11 is
It extends from the hermetic sealing window 54 in the optical axis direction. The other end of the cylindrical portion 18 (the side facing the hermetic sealing window 54)
Is provided with an optical fiber (a second optical fiber; hereinafter, referred to as a light guiding fiber 58) inserted into the ferrule 56. The light-guiding fiber 58 has a tip 58a.
Are arranged so as to face the emission side end face 12b of the semiconductor light emitting element 12, so that the laser light emitted from the emission side end face 12b of the semiconductor light emitting element 12 can be guided to another optical element or the like. ing. Here, in particular, the distal end portion 58a of the light guiding fiber 58 is processed into a spherical shape, and a low reflection film (not shown) made of a dielectric multilayer film having a reflectance of the distal end portion 58a of about 0.1%. ) Is formed. The end face 56 a of the end face of the ferrule 56 which faces the semiconductor light emitting element 12 is the semiconductor light emitting element 1.
2 is formed obliquely with respect to the optical axis so as to remove unnecessary reflected return light to the optical axis 2.

Between the hermetic sealing window 54 and the distal end portion 58a of the light guiding fiber 58, light traveling in the direction from the emission side end surface 12b of the semiconductor light emitting element 12 toward the distal end portion 58a of the light guiding fiber 58. An optical isolator 60 that selectively transmits light is disposed. Further, a lens 62 for condensing the light passing through the optical isolator 60 on the distal end portion 58a of the light guiding fiber 58 is provided downstream of the optical isolator 60.
It is accommodated and disposed in the lens holder 64.

Next, the operation and effect of the light emitting element module according to the present embodiment will be described. FIG. 3 shows a light emitting element module including an optical fiber having a built-in diffraction grating and a semiconductor light emitting element.
FM in 5 GHz band (corresponding to 2.5 GHz NRZ modulation)
This shows the relationship with the response. Here, the FM response refers to a value obtained by dividing the spread (MHz) of the emission spectrum width due to the application of the modulation current by the modulation current (mA). The smaller the FM response, the smaller the influence of the chirping phenomenon. The values shown in FIG. 3 indicate that the reflectivity of the fiber-side end face of the semiconductor light emitting device is 0.1% and the optical coupling efficiency between the fiber with a built-in diffraction grating and the semiconductor light emitting device is -4 dB.
It is the result when it is set as. As can be seen from FIG. 3, when the reflectance of the diffraction grating is small, the FM response increases, and the influence of the chirping phenomenon increases. On the other hand, when the reflectance of the diffraction grating increases, the FM response decreases, The effect of the ping phenomenon can be reduced.

FIG. 4 shows a light emitting device module which emits laser light from the end face of the semiconductor light emitting device by generating optical resonance between the semiconductor light emitting device and the diffraction grating as in the light emitting device module 10 according to the present embodiment (FIG. FIG. 5 is a diagram illustrating the relationship between the refractive index of the diffraction grating and the output of the laser light for A) in FIG. 4 and a light emitting element module (B in FIG. 4) that transmits laser light through the diffraction grating. The values shown in FIG. 4 are values calculated under the following conditions. That is, for a light emitting element module that emits laser light from the end face of the semiconductor light emitting element, the reflectivity of the fiber side end face of the semiconductor light emitting element is 0%, the reflectivity of the emission side end face is 30%, the fiber with a built-in diffraction grating and the semiconductor light emitting element. The optical coupling efficiency with the element is -4
The optical coupling efficiency between the light guide fiber and the semiconductor light emitting element is set to -3 dB. Further, in a light emitting element module that emits laser light by passing through a diffraction grating, the reflectivity of the reflective end face of the semiconductor light emitting element is 90%, the reflectivity of the fiber side end face is 0%, and the fiber with a built-in diffraction grating and the semiconductor light emitting element. Is set to -4 dB. As can be seen from FIG. 4, in the light-emitting element module that emits laser light from the end face of the semiconductor light-emitting element, the output of the laser light increases as the refractive index of the diffraction grating increases, but the laser light is transmitted through the diffraction grating to transmit the laser light. The output of the light emitting element module peaks at a reflectance of about 10%, and the output of the laser beam decreases as the reflectance of the diffraction grating increases. In particular, when the reflectance of the diffraction grating is about 60%, the output of the laser light of the light emitting element module that emits the laser light from the end face of the semiconductor light emitting element passes through the diffraction grating and emits the laser light. Laser light output.

Here, the light emitting element module 10 according to the present embodiment generates optical resonance between the emission side end face 12 b of the semiconductor light emitting element 12 and the diffraction grating 13 of the diffraction grating built-in fiber 14, and generates the light emission side end face. With the configuration in which the laser light is emitted from 12b, the reflectance of the diffraction grating 13 can be increased. As a result, the FM response can be reduced, the chirping phenomenon can be reduced, and the high frequency characteristics can be improved.

Further, the light emitting element module 10 of the present invention
Is that the reflectance of the diffraction grating 13 is 60% or more,
It is possible to increase the ratio of light re-entering the light-emitting element out of the light incident on the diffraction grating 13. Therefore, it is possible to maintain the output of the laser light in a large state.

FIG. 5 shows a light emitting element module that emits laser light from an end face of a semiconductor light emitting element by generating optical resonance between the semiconductor light emitting element and the diffraction grating. The distance between
A frequency band in which the signal intensity represented by the difference between the maximum value and the minimum value of the output light intensity when a current that changes with time in a sine wave is injected into the light emitting element module is reduced by 3 dB as compared with the low frequency (hereinafter referred to as critical FIG. The values shown in FIG. 5 indicate that the reflectance of the diffraction grating is 70%,
This is a result when the optical coupling efficiency between the fiber with a built-in diffraction grating and the semiconductor light emitting element is -4 dB. As can be seen from FIG. 5, the critical frequency decreases as the distance between the fiber-side end face of the semiconductor light emitting device and the diffraction grating increases. That is, as the distance between the fiber-side end face of the semiconductor light emitting element and the diffraction grating increases, the signal intensity decreases even with relatively low frequency laser light.

Here, the light emitting element module 10 according to the present embodiment comprises a fiber-side end face 12 of the semiconductor light emitting element 12.
By setting the distance between a and the diffraction grating 13 to 13 mm or less, even when high-speed modulation is performed, the generation of laser light can follow the increase and decrease of carriers, and a large laser output can be obtained. Become. In particular, the value of 13 mm is a necessary and sufficient value when outputting a signal in the 1.25 GHz band (corresponding to 2.5 GHz NRZ modulation) (see FIG. 5).

FIG. 6 shows a light emitting element module that emits laser light from the end face of the semiconductor light emitting element by generating optical resonance between the semiconductor light emitting element and the diffraction grating, and has a diffraction grating with a reflectance of 70% and an emission side. The reflectivity of the end face is Rf, and the optical coupling efficiency between the fiber with a built-in diffraction grating and the semiconductor light emitting device is -4d.
B shows the relationship between Rf and the output of laser light when the optical coupling efficiency between the light guide fiber and the semiconductor light emitting element is -3 dB. As can be seen from FIG. 6, the peak of Rf = about 10%, the output of the laser beam decreases as Rf increases.

Normally, the end face formed by cleavage is 30
%, But the light emitting element module 10 according to the present embodiment has the light emitting side end face 1 of the semiconductor light emitting element 12.
A low reflection film 30 is provided on 2b so that the reflectance is 30% or less. Therefore, it is possible to increase the ratio of the laser light emitted from the emission side end face 12b and obtain a large laser light output.

In the light emitting device module 10 according to this embodiment, since the fiber 14 with a built-in diffraction grating and the semiconductor light emitting device 12 are fixed to the same base 38, the fiber 14 with a built-in diffraction grating and the semiconductor light emitting device 12 And the tip 14a of the fiber 14 with a built-in diffraction grating is connected to the fiber-side end surface 12a of the semiconductor light emitting element 12.
a can be easily approached.

Further, the light emitting element module 10 according to the present embodiment includes the Peltier element 42 for cooling the fiber 14 with a built-in diffraction grating and the semiconductor light emitting element 12.
It is possible to control the temperatures of the diffraction grating built-in fiber 14 and the semiconductor light emitting element 12. As a result, stable laser oscillation becomes possible.

In the light emitting device module 10 according to the present embodiment, the light emitted from the fiber side end surface 12a of the semiconductor light emitting device 12 is formed by forming the tip portion 14a of the diffraction grating built-in fiber 14 into a spherical shape. The light can be condensed and introduced into the fiber 14 with a built-in diffraction grating, and the light emitted from the tip 14 a of the fiber 14 with a built-in diffraction grating can be condensed and made incident on the fiber-side end surface 12 a of the semiconductor light emitting element 12.

Further, the light emitting element module 10 according to the present embodiment has a rear end portion 14 b
However, since the light is obliquely cut with respect to the optical axis, unnecessary reflected light at the rear end portion 14b does not satisfy the condition of total reflection in the fiber 14 with a built-in diffraction grating, and disappears. As a result, the unnecessary reflected light does not become noise.

Further, the light emitting element module 10 according to the present embodiment has the photodiode 46 disposed so as to face the rear end portion 14b of the fiber 14 with a built-in diffraction grating, thereby detecting the output light amount of the light emitting element module 10. can do. Therefore, the output light amount can be controlled based on the light amount detected by the photodiode 46.

The light emitting element module 10 according to the present embodiment includes the light guide fiber 58, so that the laser light emitted from the emission end face 12b of the semiconductor light emitting element 12 can be efficiently propagated to other optical members. It is possible to do.

Further, in the light emitting element module 10 according to the present embodiment, the light emitted from the emission side end face 12b of the semiconductor light emitting element 12 is formed by forming the distal end portion 58a of the light guiding fiber 58 into a spherical shape. Condensing and guiding fiber 5
8 can be introduced.

Further, the light emitting element module 10 according to the present embodiment includes the optical isolator 60 so that the light reflected at the distal end portion 58 a of the light guiding fiber 58 and the light guiding fiber 58 can be connected to the semiconductor light emitting element 12. The light propagating in the direction described above does not enter the emission side end face 12a of the semiconductor light emitting element 12.

In the semiconductor light emitting device module 10 according to the above embodiment, the tip end portion 14a of the fiber 14 with a built-in diffraction grating is polished into a spherical shape. Tip 14a of
May be cut obliquely with respect to the optical axis, and a lens 66 may be disposed between the front end portion 14a and the fiber-side end surface 12a of the semiconductor light emitting element 12. By cutting the tip 14a of the diffraction grating built-in fiber 14 obliquely with respect to the optical axis, unnecessary reflected light reflected at the tip 14a is prevented from entering the semiconductor light emitting element 12 or the diffraction grating 13. . Furthermore, by providing the lens 66,
The light emitted from the fiber-side end surface 12a of the semiconductor light-emitting element 12 can be condensed and introduced into the fiber 14 with a built-in diffraction grating, and the tip 14a of the fiber 14 with a built-in diffraction grating.
Light emitted from the semiconductor light emitting element 12 can be condensed and incident on the fiber side end surface 12a of the semiconductor light emitting element 12.

Further, in the light emitting element module 10 according to the above embodiment, two lenses 52 and 62 and the optical isolator 60 are provided between the semiconductor light emitting element 12 and the light guiding fiber 58. As shown in FIG. 8, the distal end portion 58 a of the light guiding fiber 58 may be arranged close to the emission side end surface 12 a of the semiconductor light emitting element 12 without interposing a lens or an optical isolator.

Further, as shown in FIG. 9, one lens 68 is provided between the semiconductor light emitting element 12 and the light guiding fiber 58.
Alternatively, the configuration may be such that the optical isolator 60 is provided. Further, the distal end portion 58a of the light guiding fiber 58 may be cut obliquely with respect to the optical axis.

[0062]

According to the light emitting element module of the present invention, optical resonance is generated between the first end face of the light emitting element and the diffraction grating of the first optical fiber, and laser light is emitted from the second end face. Thus, the reflectance of the diffraction grating can be increased. As a result, the FM response can be reduced, the chirping phenomenon can be reduced, and the high frequency characteristics can be improved.

Further, in the light emitting element module of the present invention, by setting the reflectance of the diffraction grating to 60% or more, the proportion of the light incident on the diffraction grating that is re-incident on the light emitting element can be increased. Therefore, it is possible to maintain the output of the laser light in a large state.

Further, the light emitting device module of the present invention
By setting the distance between the first end face of the light emitting element and the diffraction grating to be 13 mm or less, even when performing high-speed modulation, the generation of laser light can follow the increase and decrease of carriers,
A large laser output can be obtained. In particular, the value of 13 mm is in the 1.25 GHz band (2.5 GHz band).
NRZ modulation) signal is output,
It is a necessary and sufficient value.

Further, in the light emitting element module of the present invention, since the first optical fiber and the light emitting element are fixed to the same base, positioning of the first optical fiber and the light emitting element becomes easy. .

Further, in the light emitting element module of the present invention, since the cooling means for cooling the first optical fiber and the light emitting element is provided, the temperature of the first optical fiber and the light emitting element can be controlled. It becomes possible. As a result, stable laser oscillation becomes possible.

Further, in the light emitting device module of the present invention, a low reflection film is provided on the second end face of the light emitting device so that the reflectance is 30% or less. Therefore, it is possible to increase the ratio of the laser light emitted from the second end face and obtain a large laser output.

Further, in the light emitting device module of the present invention, since one end of the first optical fiber is processed into a spherical shape, the light emitted from the first end face of the light emitting device is collected. And can be introduced into the first optical fiber,
Light emitted from one end of the first optical fiber can be collected and made incident on the first end face of the light emitting element.

In the light emitting device module of the present invention, the other end of the first optical fiber is cut obliquely with respect to the optical axis, so that unnecessary reflected light at the other end is cut off. Does not satisfy the condition of total reflection in the first optical fiber and disappears. As a result, the unnecessary reflected light does not become noise.

Further, in the light emitting element module of the present invention, the light quantity output from the light emitting element module can be detected by providing the light receiving element arranged opposite to the other end of the first optical fiber. it can. Therefore, the output light amount can be controlled based on the light amount detected by the light receiving element.

Further, in the light emitting element module of the present invention, by providing the second optical fiber, the laser light emitted from the second end face of the light emitting element can be efficiently propagated to other optical members and the like. It becomes possible.

Further, in the light emitting device module of the present invention, since the one end of the second optical fiber is processed into a spherical shape, light emitted from the second end surface of the light emitting device is condensed. Then, it can be introduced into the second optical fiber.

In the light emitting device module of the present invention, by providing the optical isolator, the light reflected at one end of the second optical fiber and the second optical fiber propagate in the direction of the light emitting device. Light is the second light emitting element
Is not incident on the end face of.

[Brief description of the drawings]

FIG. 1 is a sectional view of a light emitting element module.

FIG. 2 is a partially enlarged sectional view of a light emitting element module.

FIG. 3 is a graph showing the relationship between the reflectance of the diffraction grating and the FM response.

FIG. 4 is a graph showing the relationship between the reflectance of a diffraction grating and the output of laser light.

FIG. 5 is a graph showing a relationship between a distance between a semiconductor light emitting element and a diffraction grating and a frequency band.

FIG. 6 is a graph showing the relationship between the reflectance of the end face of the semiconductor light emitting element and the output of laser light.

FIG. 7 is a partially enlarged sectional view of a light emitting element module.

FIG. 8 is a partially enlarged sectional view of the light emitting element module.

FIG. 9 is a partially enlarged sectional view of a light emitting element module.

[Explanation of symbols]

10 ... Light-emitting element module, 11 ... Housing, 12 ...
Semiconductor light emitting element, 13: diffraction grating, 14: fiber with a built-in diffraction grating, 16: main body, 18: cylindrical portion, 20: substrate,
22 lower clad layer, 24 active layer, 26 upper clad layer, 28, 30 low reflection film, 34 heat sink,
36: chip carrier, 38: base, 40, 56: ferrule, 42: Peltier element, 44: thermistor, 46
... photodiode, 48 ... support member, 50,64 ... lens holder, 52,62,66,68 ... lens, 54 ...
Hermetically sealed window, 58: light guide fiber, 60: optical isolator

Claims (10)

[Claims] 1. A light emitting element having a waveguide formed on a substrate and first and second end faces each including an end of the waveguide, and a diffraction grating built therein, and one end is provided with the light emitting element. A first optical fiber disposed so as to face the first end face of the element, wherein the reflectance of the diffraction grating is 60% or more; and the first end face of the light emitting element, the diffraction grating, Is 13 mm or less, generating optical resonance between the second end face and the diffraction grating through the waveguide of the light emitting element, and emitting laser light from the second end face. Characteristic light emitting element module. 2. The light emitting device module according to claim 1, wherein the first optical fiber and the light emitting device are fixed to a same base. 3. The light emitting device module according to claim 1, further comprising a cooling unit for cooling the first optical fiber and the light emitting device. 4. The method according to claim 1, wherein a dielectric multilayer film is formed on the second end face, and the reflectivity of the second end face is 30% or less. Light emitting element module. 5. The optical fiber according to claim 1, wherein the one end of the first optical fiber is processed into a spherical shape.
The light-emitting element module according to any one of Items 1 to 4, wherein 6. The other end of the first optical fiber,
The light emitting element module according to claim 1, wherein the light emitting element module is cut obliquely with respect to an optical axis. 7. The light-emitting element module according to claim 1, further comprising a light-receiving element disposed to face the other end of said first optical fiber. . 8. A light-emitting device further comprising: a second optical fiber disposed so that one end thereof is opposed to the second end surface of the light-emitting element, and guides a laser beam emitted from the second end surface. The method according to claim 1, wherein
A light-emitting element module according to the item. 9. The optical fiber according to claim 8, wherein the one end of the second optical fiber is processed into a spherical shape.
The light-emitting element module according to item 1. 10. Light traveling between the second end face of the light emitting element and the one end of the second optical fiber in a direction from the second end face to the one end. A light emitting element module further comprising an optical isolator that selectively transmits light.