JP3755176B2 - Light emitting element module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emitting element module.
[0002]
[Prior art]
As a conventional light emitting element module, as shown in FIG. 11, a module including a semiconductor light emitting element A serving as a light emitting source and an optical fiber B serving as a light guide is known. The semiconductor light-emitting element A of the light-emitting element module is configured by joining a p-type semiconductor and an n-type semiconductor, and a light-reflecting surface C having a high reflectance and a low-reflectance surface are formed on opposite sides of the semiconductor light-emitting element A. A light exit surface D is provided. On the other hand, the optical fiber B is provided with a diffraction grating F formed by forming a plurality of high refractive index regions at a predetermined pitch on the core E, and the diffraction grating F and the light reflection surface C constitute a resonator. ing. According to such a light emitting element module, light is generated therein by current injection into the semiconductor light emitting element A, and the light is reflected back and forth between the light reflecting surface C and the diffraction grating F of the optical fiber B and amplified. As a result, laser light H having a single wavelength determined by the pitch of the diffraction grating F can be output through the optical fiber B.
[0003]
[Problems to be solved by the invention]
However, the conventional light emitting element module has the following problems. The semiconductor light emitting device A and the optical fiber B are not optically coupled efficiently, and the laser beam H cannot be output efficiently. That is, in order to efficiently amplify the light generated in the semiconductor light emitting element A and output it as the laser light H, the optical coupling efficiency between the semiconductor light emitting element A and the optical fiber B is important. The optical fibers B are both very small, and it is very difficult to accurately arrange them with the optical axes aligned. For this reason, when the optical fiber B is misaligned with respect to the semiconductor light emitting element A, the energy loss of light reciprocating between the light reflecting surface C of the semiconductor light emitting element A and the diffraction grating F of the optical fiber B is large, and the efficiency The light cannot be amplified well. Therefore, the laser beam H cannot be output efficiently, resulting in variations in the output characteristics of the light emitting element module when mass-produced. In order to cope with such a problem, there is an urgent need for technical development for improving the optical coupling efficiency between the semiconductor light emitting element A and the optical fiber B.
[0004]
Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a light emitting element module that efficiently outputs laser light.
[0005]
[Means for Solving the Problems]
That is, the present invention includes a core and a clad, and includes an enlarged diameter portion at an end portion of the core, a diffraction grating that reflects only light of a specific wavelength in at least the enlarged diameter portion, and the diffraction grating An optical fiber having a high refractive index region periodically provided along the light guide direction, and a semiconductor light emitting device having a light reflecting surface and a light emitting surface facing each other across the active region, A light emitting element module , wherein a light exit surface and an end portion of the optical fiber having the enlarged diameter portion are optically coupled, and a resonator is substantially formed by the light reflecting surface and the diffraction grating. is there.
[0006]
According to the present invention , since the diameter-increased portion is formed in the core to which light is incident, the light is reliably incident and emitted even when the core is misaligned with respect to the optical coupling target. A decrease in the photo-coupling efficiency is prevented.
[0007]
According to another aspect of the present invention, there is provided a light emitting element module including the above-described diffraction grating having a high refractive index region periodically provided with an equal optical path length along a light guide direction. According to such an invention, even when the diffraction grating is formed in the enlarged diameter portion having a different refractive index along the light guide direction, the optical paths in which the intervals of the high refractive index regions forming the diffraction grating are equal. Since it is long, only light of a single wavelength is reflected.
[0008]
Moreover, this invention is a light emitting element module characterized by the end part provided with the above-mentioned enlarged diameter part being tip-ball processed. According to such an invention, since the light incident on the optical fiber is collected toward the core, the optical coupling efficiency can be improved.
[0009]
According to another aspect of the present invention, there is provided a light emitting element module comprising a reflection reducing film on an end face provided with the above-described enlarged diameter portion. According to such an invention, since the light incident on the optical fiber is guided without being reflected by the end face of the optical fiber, the characteristic deterioration due to the reflection is avoided and the optical coupling efficiency is improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment according to the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and description is abbreviate | omitted. Further, the dimensional ratios in the drawings do not necessarily match those described.
[0018]
FIG. 1 is a schematic diagram of an optical fiber 1. In FIG. 1, an optical fiber 1 has a thin core 3 formed by adding a refractive index increasing material such as germania (GeO ₂ ) in a clad 2 made of quartz (SO ₂ ) or the like along an axial direction. It is a wire having a diameter and has a structure for guiding light along the core 3 having a high refractive index. The optical fiber 1 has a diameter-expanded portion 31 formed in the core 3 at the end thereof. The enlarged diameter portion 31 is a portion where the mode field diameter of the end face 11 of the optical fiber 1 is enlarged, and is formed by increasing the diameter of the core 3 of the optical fiber 1 as shown in FIG. The shape is such that the field diameter gradually increases toward the end face 11. By forming such an enlarged diameter portion 31 at the end of the core 3, even if the light irradiated toward the end surface 11 of the optical fiber 1 is misaligned, the light is reliably guided into the core 3. Thus, the efficiency of optical coupling with the outside can be improved.
[0019]
On the other hand, a diffraction grating 32 that reflects only light of a predetermined wavelength is formed in the middle of the core 3. As shown in FIG. 1, the diffraction grating 32 includes a plurality of high refractive index regions 33 formed along the axial direction of the optical fiber 1, that is, along the light guide direction of the core 3. By setting the optical path lengths to be equal to each other, only light having a wavelength of λ in the following formula (1) is selectively reflected.
[0020]
λ = 2 · n · Λ (1)
n: effective refractive index Λ in core 3: interval (period) of high refractive index region 33
In FIG. 1, the diffraction grating 32 is formed in the enlarged diameter portion 31, and the refractive index tends to gradually decrease toward the end face 11 in the enlarged diameter portion 31. The distance Λ is gradually formed toward the end face 11 at a wide distance. The high refractive index region 33 may be formed using an interference exposure method using ultraviolet irradiation. That is, the high refractive index region 33 is formed by irradiating ultraviolet rays from the outside of the optical fiber 1 and increasing the refractive index of the core 3 to which germanium is added by the irradiation. By irradiating the core 3 with an interference fringe corresponding to the period Λ, the high refractive index region 33 is formed with a predetermined period Λ. By forming such a diffraction grating 32 on the core 3, only light having a predetermined wavelength among the light incident from the end face 11 of the optical fiber 1 is reflected toward the end face 11.
[0021]
Further, the above-described diffraction grating 32 may be formed other than the enlarged diameter portion 31 of the core 3. That is, when the diffraction grating 32 is formed across the enlarged diameter portion 31 and other portions as shown in FIG. 2, the diffraction grating 32 is the core 3 other than the enlarged diameter portion 31 as shown in FIG. Even in the case where the high refractive index region 33 is formed with an equal optical path length, only light of a predetermined wavelength can be reflected.
[0022]
Further, the end portion of the optical fiber 1 may be processed into a tip. For example, as shown in FIG. 4, the optical fiber 1a has a structure in which an end surface 11a protrudes outwardly in a convex mirror shape or a hemispherical shape, and the end surface 11a is irradiated by having such a structure. Since the light is condensed on the core 3 of the axial center, the optical coupling efficiency with the outside is good. For example, when the mode field diameter on the end face 11a is 35 μm, the tip ball processing is formed so as to protrude to a curvature radius of 20 μm.
[0023]
Furthermore, a reflection reducing film that reduces the light reflectance may be attached to the end face of the optical fiber. That is, as shown in FIG. 5, the optical fiber 1 b is provided with a dielectric multilayer film 12 that is a reflection reducing film on the end face 11, so that the light irradiated to the end face 11 does not reflect on the end face 11. Thus, the light is reliably incident on the core 3. This dielectric multilayer film 12 is a film body formed by laminating thin films such as silica (SiO ₂ ) and titania (TiO ₂ ) in several layers, and the refractive index, thickness and number of layers of the material of the film. By appropriately changing, it is possible to arbitrarily set the light reflectance at a specific wavelength.
[0024]
Next, the light emitting element module 6 using the above-described optical fiber 1 or 1a, 1b will be described.
[0025]
As shown in FIG. 6, the light emitting element module 6 includes the above-described optical fiber 1 or 1 a, 1 b (hereinafter referred to as the optical fiber 1) and the semiconductor light emitting element 4. The semiconductor light emitting device 4 has an active region 41 that generates and amplifies light, and includes a light reflecting surface 42 having a high light reflectance and a light emitting surface 43 having a low light reflectance facing each other across the active region 41. The structure is provided. Light is generated by injecting current into the active region 41, and the light is reflected by the light reflecting surface 42 and emitted from the light emitting surface 43. As the semiconductor light emitting element 4, for example, an InGaAsP / InP double heterostructure is adopted as in a general Fabry-Perot type semiconductor laser, and an active region 41 made of InGaAsP is interposed between cladding layers 44, 44 made of InP. Is disposed. The active region 41 has a refractive index larger than that of the cladding layer 44 due to the use of a mixed crystal, and light is guided along the active region 41.
[0026]
As a means for injecting current in the semiconductor light emitting device 4, for example, a device in which a drive circuit for current injection (not shown) is connected to the semiconductor light emitting device 4 is adopted, and current can be supplied to the active region 41 through the cladding layers 44 and 44. What is necessary is just to comprise. A predetermined operating current flows from the driving circuit to the semiconductor light emitting element 4 to excite the active region 41 to generate spontaneous emission light. The spontaneous emission light advances the active region while causing stimulated emission, The light is emitted from the light exit surface 43 together with the stimulated emission light. The semiconductor light emitting device 4 is not limited to the above-described InGaAsP / InP double heterostructure, but generates and amplifies light, and has the light reflecting surface 42 and the light emitting surface 43 described above. Any other semiconductor may be used.
[0027]
On the other hand, as shown in FIG. 6, the optical fiber 1 described above is optically coupled to the light emitting surface 43 side of the semiconductor light emitting element 4 so that light can enter and exit the light emitting surface 43. Is arranged. For example, the optical fiber 1 is arranged so that the end surface 11 thereof is opposed to the light emitting surface 43 of the semiconductor light emitting element 4, and the light emitted from the light emitting surface 43 can be incident thereon. Light can be emitted toward the emission surface 43. In the optical fiber 1, the diffraction grating 32 formed in the core 3 constitutes a laser resonator together with the light reflecting surface 42 of the semiconductor light emitting element 4. That is, the light generated in the semiconductor light emitting element 4 is amplified while being reflected back and forth between the light reflecting surface 42 and the diffraction grating 32, and is output as the laser light 5 through the optical fiber 1. Further, if the diffraction grating 32 is formed in the vicinity of the end of the optical fiber 1, that is, in the enlarged diameter portion 31 of the core 3, the diffraction grating 32 is positioned in the package that houses the semiconductor light emitting element 4. Since the external influence (external force applied to the optical fiber 1, heat, etc.) is reduced, the laser light output characteristics of the light emitting element module 6 are stabilized.
[0028]
Although not shown, a lens system for coupling light traveling between them may be provided between the semiconductor light emitting element 4 and the optical fiber 1. For example, a rod lens or a cylindrical lens that is separate from the semiconductor light emitting element 4 and the optical fiber 1 is disposed to focus the spread of light emitted from the light emitting surface 43 of the semiconductor light emitting element 4 or the core 3 of the optical fiber 1. Then, the core 3 and the light emitting surface 43 are optically coupled. By the arrangement of this lens system, when light reciprocates between the light reflecting surface 42 of the semiconductor light emitting element 4 and the diffraction grating 32 of the optical fiber 1, optical coupling between the semiconductor light emitting element 4 and the optical fiber 1 is performed. Efficiency can be improved.
[0029]
Next, the operation of the light emitting element module 6 will be described.
[0030]
In FIG. 6, a predetermined voltage is applied between the clad layers 44 and 44 of the semiconductor light emitting device 4 to inject current into the clad layers 44 and the active regions 41. Then, the active region 41 is excited and emits spontaneous emission light. This spontaneously emitted light causes stimulated emission within the active region 41, travels with the stimulated emission light, is reflected by the light reflecting surface 42 having a high reflectance, and is emitted from the light emitting surface 43 having a low reflectance. The light emitted from the light emitting surface 43 toward the optical fiber 1 travels toward the end surface 11 of the optical fiber 1, but the semiconductor light emitting element 4 and the optical fiber 1 are very small in the micro order. There is a possibility that the optical axis of the light emitted from the element 4 and the optical axis of the core 3 of the optical fiber 1 are arranged with a slight misalignment. However, even in such a case, since the mode field diameter of the optical fiber 1 is enlarged by the formation of the enlarged diameter portion 31 at the end thereof, the light emitted from the semiconductor light emitting element 4 is surely emitted. The light enters the core 3 of the fiber 1. At this time, if the end face 11 of the optical fiber 1 is processed into a tip as in the end face 11a of the optical fiber 1a, the light incident on the core 3 can be condensed on the center of the core 3. Further, if the end face 11 of the optical fiber 1 is provided with the dielectric multilayer film 12 which is a reflection reducing film like the optical fiber 1b, the light irradiated to the end face 11 is surely entered into the core 3 without being reflected. It becomes possible to make it enter.
[0031]
Then, only the light having a predetermined wavelength is reflected by the diffraction grating 32 disposed in the middle of the core 3. That is, when light reaches a plurality of high refractive index regions 33 separated by an equal optical path length Λ, only the wavelength λ corresponding to the Λ (the wavelength λ satisfying the above-described equation (1)) is selectively selected from the optical fiber 1. It will be reflected toward the end 11 side. The light having the specific wavelength is emitted from the end face 11 of the optical fiber 1, enters the active region 41 of the semiconductor light emitting element 4, travels through the active region 41, and is reflected by the light reflecting surface 42 while being amplified again. . In this way, the light is amplified by repeatedly reciprocating between the light reflecting surface 42 and the diffraction grating 32 of the optical fiber 1, and then transmitted through the diffraction grating 32 and output as the desired laser light 5 through the optical fiber 1. To go.
[0032]
According to such a light emitting element module 6, since the diffraction grating 32 is formed in the optical fiber 1, it is possible to output laser light having a single wavelength, and the enlarged diameter portion 31 is formed in the optical fiber 1. Optical coupling between the semiconductor light emitting element 4 and the optical fiber 1 is efficiently performed, and laser light can be output efficiently.
[0033]
Next, a method for manufacturing the above-described optical fiber 1 will be described.
[0034]
In FIG. 7, a fiber original wire 10 having an enlarged diameter portion 30 formed in the middle portion of the core 3 is prepared, and the reference light 7 is incident from one end side of the fiber original wire 10 and transmitted through the other end side. The fiber original line 10 is set so that the wavelength-light intensity characteristic of the light 8 can be measured. The fiber original wire 10 serves as a base of the optical fiber 1 to be manufactured. The diameter-expanded portion 30 of the core 3 is heated in the middle of the fiber original wire 10 with a burner or the like, and germanium added to the core 3 is added. It is formed by diffusing a refractive index increasing material such as. A known light source device or the like may be used as the incident means for the reference light 7, and a known light receiving device or the like may be used as the light receiving means for the transmitted light 8. The enlarged diameter portion 30 of the fiber original wire 10 is obtained by enlarging the mode field diameter similarly to the aforementioned enlarged diameter portion 31. Further, as the reference light 7, it is preferable to use light having each wavelength component almost uniformly in a predetermined wavelength band, for example, white light is adopted.
[0035]
Then, the reference light 7 is incident from one end side of the fiber original line 10 and the fiber original line 10 is irradiated with ultraviolet rays 91 while measuring the characteristics of the transmitted light 8 transmitted to the other end side. Irradiation of the ultraviolet rays 91 is performed from two directions toward the fiber original wire 10, and interference fringes are formed at predetermined intervals by the ultraviolet rays 91 in the axial direction of the core 3. The interval between the interference fringes is set so as to be the period Λ of the desired high refractive index region 33 described above. Due to the irradiation of the ultraviolet rays 91, the refractive index of the core 3 of the fiber original wire 10 increases according to the intensity of the ultraviolet rays, and a plurality of high refractive index regions 33, that is, diffraction gratings 32 are formed. At this time, as shown in FIG. 7, the diffraction grating 32 can be formed while measuring the wavelength-light intensity characteristic of the transmitted light 8, so that only a predetermined wavelength is reflected while finely adjusting the light reflection characteristic of the diffraction grating 32. Can be.
[0036]
Then, as described above, the diffraction gratings 32 and 32 are provided on both sides of the enlarged diameter portion 30, respectively. At this time, the second diffraction grating 32 may be formed while subtracting the portion due to the reflection characteristic of the first diffraction grating 32 and measuring the wavelength-light intensity characteristic of the transmitted light 8. Further, the light reflection characteristics of the diffraction gratings 32 and 32 formed on both sides of the enlarged diameter portion 30 may be equal, or different characteristics can be obtained by changing the irradiation state of the ultraviolet rays. In addition, part or all of the diffraction grating 32 may be formed in the enlarged diameter portion 30. In this case, the optical fiber 1 as shown in FIG. 1 or FIG.
[0037]
After forming the diffraction grating 32, the fiber original wire 10 is cut at substantially the center position of the enlarged diameter portion 30 as shown in FIG. 8. The cutting may be performed by cleavage. By the cutting, two optical fibers 1 are obtained from the fiber original wire 10. Further, the end face of the obtained optical fiber 1 on the side of the enlarged diameter portion 30 may be processed with a tip, and the dielectric multilayer film 12 that is a reflection reducing film may be provided.
[0038]
According to such a manufacturing method of the optical fiber 1, since the diffraction grating 32 is formed in the fiber original wire 10 having the enlarged diameter portion 30 in advance, the characteristics of the diffraction grating 32 are deteriorated by heat when the enlarged diameter portion 30 is formed. Does not cause problems such as Further, since the diffraction grating 32 is formed while measuring the light reflection characteristics of the diffraction grating 32, the light reflection characteristics of the diffraction grating 32 can be reliably formed as desired. Furthermore, since the optical fiber 1 in which the diffraction grating 32 is formed is cut into the optical fiber 1, the optical fiber 1 having the diffraction grating 32 at the outermost end can be manufactured easily and reliably.
[0039]
By the way, the optical fiber 1, 1a, or 1b may be manufactured by a method different from the above-described manufacturing method. That is, when the enlarged diameter portion 31 of the core 3 is formed at the end portion of the fiber original wire 10, it is difficult to efficiently optically couple the end portion on the enlarged diameter portion 31 side with a light receiving device or the like. For this reason, as shown in FIG. 9, while measuring the wavelength-light intensity characteristic, the reference light 7 is incident from one end of the fiber original line 10 to simultaneously form a desired diffraction grating 32 on the core 3 of the fiber original line 10. The optical fiber 1 (including 1a or 1b) having the desired diffraction grating 32 can be manufactured by measuring the wavelength-light intensity characteristic of the reflected light 71 reflected from the inside (the formed diffraction grating 32).
[0040]
A specific manufacturing method of the optical fiber 1 is as follows. First, the light source of the reference light 7 is connected to the end of the fiber original wire 10 opposite to the enlarged diameter portion 31 via the light guide 92 and the optical branching device 93. Thus, the reference light can be made incident on the end portion of the fiber original wire 10. For example, the optical branching device 93 has four terminals P1, P2, P3, and P4. The light incident on the terminal P1 is branched at a predetermined ratio, emitted from the terminals P3 and P4, and incident on the terminal P3. The light is emitted from the terminals P1 and P2 at a predetermined ratio, the terminal P1 is connected to the light source of the reference light 7, the terminal P3 and the fiber original line 10 are connected, and the terminal P4 is spectrally connected. By connecting the device 94, the reference light 7 incident on the terminal P1 is branched into the reference light 7a and the reference light 7b in the optical splitter 93, and the reference light 7a is emitted from the terminal P3 and incident on the fiber original line 10. The reference light 7b is emitted from the terminal P4 and is incident on the spectroscope 94 so that the wavelength-light intensity characteristic of the reference light 7a can be measured. Further, by connecting the spectroscope 95 to the terminal P2 of the optical branching device 93, the reflected light 71 of the reference light 7a reflected by the fiber original line 10 is incident on the terminal P3 and branched in the optical branching device 93. As the reflected light 71a, the reflected light 71a is made incident on the spectroscope 95 through the terminal P2 so that the wavelength-light intensity characteristic of the reflected light 71 can be measured.
[0041]
In this way, the wavelength-light intensity characteristics of the reference light 7 a incident on the fiber original line 10 and the reflected light 71 are made measurable, and the reference light 7 is incident on the fiber original line 10. As the reference light 7, white light may be used as described above. On the other hand, as described above, the original fiber 10 is irradiated with ultraviolet rays to form a diffraction grating 32 on the core 3. As the diffraction grating 32 is formed, the reference light 7 incident on the fiber original line 10 is reflected toward the optical splitter 93 side. The characteristic of the reflected light 71 can be measured at any time by a spectroscope 95 as shown in FIG. For example, the light intensity of the reference light 7 in the spectroscope 94 is 0 dBm at a wavelength of 1300 nm, and the branching ratio from the terminal P3 to the terminal P2 and the terminal P1 of the optical branching device 93 is 1: 1, which is shown in the spectroscope 95. When the light intensity is indicated by −6 dB at a wavelength of 1300 nm, it can be easily confirmed that the reflectance of the diffraction grating 32 at a wavelength of 1300 nm is 50%. Therefore, the light reflection characteristics of the diffraction grating 32 can be easily made desired by irradiating the fiber original line 10 with ultraviolet rays while measuring the light intensity of the reflected light 71 of the spectroscope 95.
[0042]
At this time, if the dielectric multilayer film 12 which is a reflection reducing film is previously attached to the end face of the fiber original wire 10 on the diameter-expanded portion 31 side, reflection at the end face is prevented. Only the characteristic can be measured by the spectroscope 95, and a desired reflection characteristic in the diffraction grating 32 can be obtained with certainty. Also, if the end surface on the end of the enlarged diameter portion 31 is preliminarily processed, reflection at the end surface is similarly prevented, and only the reflection characteristics of the diffraction grating 32 can be measured by the spectroscope 95. Thus, the desired reflection characteristics at 32 can be obtained with certainty. Then, when the desired diffraction grating 32 is formed on the fiber original wire 10, the manufacturing is completed.
[0043]
According to such a manufacturing method of the optical fiber 1, even when the diameter-expanded portion 31 of the core 3 is formed at the end of the fiber original wire 10, the diffraction grating 32 having desired characteristics is provided on the core 3. It can be reliably formed.
[0044]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained. That is, in the light emitting element module according to the present invention, the diameter-increased portion is formed in the light incident core, so that even when the core is misaligned with respect to the optical coupling target, Since the emission is reliably performed, a decrease in optical coupling efficiency can be prevented, and the optical coupling property is excellent. Further, the diffraction grating is composed of a plurality of high refractive index regions provided in the light guide direction of the core, and the intervals between the high refractive index regions are equal to each other, so that the diffraction grating is aligned along the light guide direction. Even in the case of being formed in the enlarged diameter portions having different refractive indexes, only light having a single wavelength can be reflected. In addition, since the end of the optical fiber is processed into a sphere, light incident on the optical fiber is collected toward the core, so that the optical coupling efficiency can be improved. Further, since the reflection reducing film is provided on the end face of the optical fiber, the light incident on the optical fiber is guided without being reflected by the end face of the optical fiber, so that the optical coupling efficiency can be improved. .
[0045]
Further, in the light emitting element module according to the present invention, since the optical coupling between the semiconductor light emitting element and the optical fiber is performed efficiently, a single wavelength laser beam can be output efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an optical fiber according to an embodiment.
FIG. 2 is a schematic diagram of an optical fiber according to an embodiment.
FIG. 3 is a schematic diagram of an optical fiber according to an embodiment.
FIG. 4 is a schematic diagram of an optical fiber according to an embodiment.
FIG. 5 is a schematic diagram of an optical fiber according to an embodiment.
FIG. 6 is a schematic view of a light emitting element module according to an embodiment.
FIG. 7 is an explanatory diagram of an optical fiber manufacturing method according to the embodiment.
FIG. 8 is an explanatory diagram of a method for manufacturing an optical fiber according to an embodiment.
FIG. 9 is an explanatory diagram of a method for manufacturing an optical fiber according to an embodiment.
FIG. 10 is an explanatory diagram of a method for manufacturing an optical fiber according to an embodiment.
FIG. 11 is an explanatory diagram of a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 2 ... Cladding, 3 ... Core, 31 ... Diameter expansion part, 32 ... Diffraction grating 33 ... High refractive index area | region

Claims (4)

A core and a clad, having an enlarged diameter portion at an end of the core, at least a diffraction grating reflecting only light of a specific wavelength in the enlarged diameter portion, and the diffraction grating along the light guide direction An optical fiber with a periodically provided high refractive index region;
A semiconductor light emitting device having a light reflecting surface and a light emitting surface facing each other across the active region;
With
The light emitting surface and an end portion of the optical fiber having the diameter-expanded portion are optically coupled, and a resonator is substantially formed by the light reflecting surface and the diffraction grating;
The light emitting element module characterized by the above.   The light-emitting element module according to claim 1, wherein the high refractive index region of the diffraction grating is periodically provided with an equal optical path length along the light guide direction.   The light emitting element module according to claim 1, wherein an end portion provided with the diameter-expanded portion is processed into a tip.   The light emitting element module according to claim 1, further comprising a reflection reducing film on an end surface provided with the diameter-expanded portion.

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