JP2005062347A - Optical module and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module and a manufacturing method therefor which do not cause a great reduction in mechanical strength of a ferrule, eliminating the need for forming precise grooves for securing excessive transmission loss and wavelength selectivity to transmission and receiving light, and can avoid a decrease in yield of manufacturing the optical module due to breakage of a wavelength filter. <P>SOLUTION: The optical module has an optical fiber 2 formed with a fiber grating part 7 having a radiation mode, a ferrule 1 formed with a notched flat part 5 for a photoreceptor which exposes at least a part of the optical fiber side face of the part formed with the fiber grating part, a photoreceptor 9 for receiving radiation light radiated from the optical fiber side face of the part formed with the fiber grating part, and a substrate 9 on which the photoreceptor is packaged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical module for optical communication and an optical module manufacturing method.

  Conventionally, various modules have been developed as optical modules for optical communication. Hereinafter, a conventional optical module for optical communication will be described with reference to FIG. As shown in FIG. 14, the optical module includes a ferrule 1, a light receiving element notch flat portion 5 formed on the ferrule 1, a substrate 8, a light receiving element 9, an optical adhesive 10, a first optical fiber 21, and a second optical fiber. 22, a first optical fiber end face 31, a second optical fiber end face 32, a filter insertion groove 33, and a wavelength filter 34.

Received light (not shown) that has propagated through the first optical fiber 21 is emitted from the end face 31 of the first optical fiber, and due to the wavelength selectivity of the wavelength filter 34 inserted into the filter insertion groove 33 formed in the ferrule 1. Receives reflection. The reflected received light (not shown) is incident on the light receiving element 9 mounted on the substrate 8 fixed on the light receiving element notch flat portion 5 by the optical adhesive 10, and is photoelectrically converted in the light receiving element 9. On the other hand, transmission light (not shown) propagating through the second optical fiber 22 is emitted from the second optical fiber end face 32, then passes through the wavelength filter 34 and enters the first optical fiber end face 31, and the first optical fiber 21. Propagate inside. Such an optical module for optical communication is disclosed in Patent Document 1 below.
International Publication No. 97/06458 (FIG. 2)

  However, in the conventional optical module disclosed in Patent Document 1, since the wavelength filter 34 having a wavelength demultiplexing function is inserted between the first optical fiber 21 and the second optical fiber 22, The filter insertion groove 33 needs to be formed. In such an optical module configuration, when a load is applied to the ferrule 1, there is a problem that the mechanical strength of the ferrule 1 is significantly reduced because stress concentrates on the filter insertion groove 33.

  Further, in order to ensure the excessive transmission loss and wavelength selectivity for the transmitted / received light required for the optical module, the optical coupling between the first optical fiber 21 and the second optical fiber 22 is enhanced, and the first optical fiber end face It is necessary to make the incident angle of the received light (not shown) emitted from 31 with respect to the wavelength filter 34 constant and to suppress the spread. Therefore, the filter insertion groove 33 needs to be a parallel, sufficiently narrow width and precise angle-controlled groove, but it is difficult to form a precise groove that does not vary by mechanical processing such as cutting. is there. On the other hand, it is necessary to reduce the thickness of the wavelength filter 34 in accordance with the filter insertion groove 33. However, since the mechanical strength of the wavelength filter 34 decreases as the thickness decreases, the wavelength filter 34 is inserted into the filter insertion groove 33. At this time, there is also a problem that the wavelength filter 34 is damaged and the yield of manufacturing the optical module is lowered.

  The present invention has been made to solve the above problems, and it is necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity with respect to transmitted / received light without significantly reducing the mechanical strength of the ferrule. Therefore, an object of the present invention is to provide an optical module and an optical module manufacturing method capable of avoiding damage to the wavelength filter and reducing the yield of optical module manufacturing.

  In order to achieve the above object, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a ferrule in which a notch flat portion for a light receiving element is formed, and an optical fiber in a portion in which the fiber grating is formed. A light receiving element that receives radiated light emitted from the side surface and a substrate on which the light receiving element is mounted are provided. That is, an optical fiber in which a fiber grating having a radiation mode is formed, and a ferrule in which a notch flat portion for a light receiving element that exposes at least a part of a side surface of the optical fiber in a portion in which the fiber grating is formed, An optical module is provided that includes a light receiving element that receives radiated light emitted from the side surface of the optical fiber in a portion where the fiber grating is formed, and a substrate on which the light receiving element is mounted. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases.

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a notch flat portion for a light receiving element that exposes at least a part of a side surface of the optical fiber in a portion in which the fiber grating is formed, and exposure. A ferrule having a notched flat portion, a light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed, and a substrate on which the light receiving element is mounted. An optical module is provided. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases.

  In the optical module of the present invention, the optical axis of the optical fiber from the center point of the light receiving surface of the light receiving element on a plane including the optical axis of the optical fiber and the center point of the light receiving surface of the light receiving element. The intersection point on the optical axis perpendicular to the reference point is defined as a reference point, the distance on the optical axis of the optical fiber with respect to the reference point is z, and the light receiving element of the optical fiber of the fiber grating with respect to the optical axis of the optical fiber When the light emission angle to the center point of the light receiving surface is θ and the vertical distance between the center point of the light receiving surface of the light receiving element and the optical fiber is h, z = h / tan θ is satisfied. This is a preferred embodiment of the present invention. With this configuration, the light coupling efficiency between the emitted light and the light receiving element can be increased by changing the light emission angle at the position of each fiber grating portion on the optical fiber optical axis.

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a notch flat portion for a light receiving element that exposes at least a part of a side surface of the optical fiber in a portion in which the fiber grating is formed, and A ferrule in which a flat part for exposure is formed, a light receiving element that receives radiation emitted from the side surface of the optical fiber in a part in which the fiber grating is formed, and a substrate on which the light receiving element is mounted. In the method of manufacturing an optical module, a step of bringing a fiber grating forming mask into close contact with the optical fiber exposed on the exposure notch flat portion, and irradiating the optical fiber with ultraviolet light through the fiber grating forming mask Forming the fiber grating. Optical module manufacturing method is provided, characterized in that. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases. In addition, the fiber grating portion can be easily formed.

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a light receiving element cut-out flat portion covering a side surface of the optical fiber in a portion in which the fiber grating is formed are formed of glass. There is provided an optical module comprising: a ferrule, a light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed, and a substrate on which the light receiving element is mounted. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases. Further, since the optical fiber is not exposed in the ferrule, the optical fiber is not damaged and the optical transmission characteristics are not deteriorated, and the reliability can be improved.

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a light receiving element notch flat part and an exposure notch flat part covering a side surface of the optical fiber in a part where the fiber grating is formed. A light comprising: a glass ferrule formed with: a light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed; and a substrate on which the light receiving element is mounted. A module is provided. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases. Further, since the optical fiber is not exposed in the ferrule, the optical fiber is not damaged and the optical transmission characteristics are not deteriorated, and the reliability can be improved.

  In the optical module of the present invention, the optical axis of the optical fiber from the center point of the light receiving surface of the light receiving element on a plane including the optical axis of the optical fiber and the center point of the light receiving surface of the light receiving element. The intersection point on the optical axis perpendicular to the reference point is a reference point, the distance on the optical axis of the optical fiber to the reference point is z, and the light receiving element for the optical axis of the optical fiber of the fiber grating The light emission angle to the flat surface of the notch flat part is θ, the vertical distance between the flat surface of the notch flat part for the light receiving element and the optical fiber is h1, the refractive index of the glass ferrule is n1, A vertical distance between the center of the light receiving surface of the light receiving element and the flat surface of the notched flat portion for the light receiving element is h2, and the flat surface of the light receiving surface of the light receiving element and the notched flat portion for the light receiving element is h2. It is preferable that the present invention satisfy z = (h1 / tanθ) + [h2 × tan {sin−1 ((n1 / n2) × cosθ)}] when the refractive index between the surface and the surface is n2. It is an aspect. With this configuration, the light coupling efficiency between the emitted light and the light receiving element can be increased by changing the light emission angle at the position of each fiber grating portion on the optical fiber optical axis.

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a light receiving element cut-out flat portion covering a side surface of the optical fiber in a portion in which the fiber grating is formed are formed of glass. In a method of manufacturing an optical module comprising: a ferrule of: a light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed; and a substrate on which the light receiving element is mounted. Immersing the glass ferrule in a transparent container containing a refractive index adjusting liquid having a refractive index equivalent to that of the glass ferrule; and an ultraviolet irradiation image of a fiber grating forming mask through the transparent container through a lens. A step of forming an image on the optical fiber to form the fiber grating. Optical module manufacturing method is provided, characterized in that it comprises and. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases. In addition, the fiber grating portion can be easily formed.

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a light receiving element notch flat part and an exposure notch flat part covering a side surface of the optical fiber in a part where the fiber grating is formed. A light comprising: a glass ferrule formed with: a light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed; and a substrate on which the light receiving element is mounted. In the method of manufacturing a module, the optical module includes a step of forming an image of an ultraviolet ray irradiated on a fiber grating forming mask on the optical fiber by a lens through the exposure notch flat portion to form the fiber grating. A fabrication method is provided. This configuration does not significantly reduce the mechanical strength of the ferrule, eliminates the need to form a precise groove without variation to ensure excessive transmission loss and wavelength selectivity for transmitted and received light, and damages the wavelength filter, resulting in an optical module. It can be avoided that the production yield decreases. In addition, the fiber grating portion can be easily formed.

  As described above, in the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a notch flat portion for a light receiving element that exposes at least a part of the side surface of the optical fiber in the portion where the fiber grating is formed are formed. A ferrule, a light receiving element that receives the radiated light emitted from the side surface of the optical fiber in the part where the fiber grating is formed, and a substrate on which the light receiving element is mounted, thereby significantly reducing the mechanical strength of the ferrule. Therefore, it is not necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity with respect to transmitted / received light, and it is possible to avoid that the wavelength filter is damaged and the yield of manufacturing the optical module is reduced. ).

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a notch flat part for light receiving element that exposes at least a part of a side surface of the optical fiber of the part in which the fiber grating is formed, and a notch flat for exposure A ferrule having a portion formed thereon, a light receiving element that receives radiation emitted from the side surface of the optical fiber in the portion where the fiber grating is formed, and a substrate on which the light receiving element is mounted. It is not necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity with respect to transmitted / received light without significantly lowering, and it is possible to avoid damage to the wavelength filter and decrease in the yield of optical module fabrication ( Claim 2).

  Further, according to the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, a notch flat part for light receiving element that exposes at least a part of a side surface of the optical fiber in a part in which the fiber grating is formed, and a flat for exposure In a method of manufacturing an optical module comprising: a ferrule formed with a portion; a light receiving element that receives radiated light emitted from a side surface of an optical fiber in a portion where a fiber grating is formed; and a substrate on which the light receiving element is mounted. A step of closely attaching a fiber grating forming mask to the optical fiber exposed on the exposure notch flat portion, and a step of irradiating the optical fiber with ultraviolet light through the fiber grating forming mask to form a fiber grating. , Without significantly reducing the mechanical strength of the ferrule, There is no need to form a fine groove for securing the excess transmission loss and wavelength selectivity to receive light, that yield of the optical module produced decreases wavelength filter is broken can be avoided. Further, the formation of the fiber grating portion can be facilitated (claim 4).

  Further, in the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a glass ferrule in which a notch flat portion for a light receiving element that covers a side surface of the optical fiber in a portion where the fiber grating is formed, Since it includes a light-receiving element that receives the radiated light emitted from the side surface of the optical fiber in the part where the fiber grating is formed, and a substrate on which the light-receiving element is mounted, the mechanical strength of the ferrule is not significantly reduced, and the transmitted and received light It is not necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity, and it can be avoided that the wavelength filter is broken and the yield of manufacturing the optical module is lowered. Further, since the optical fiber is not exposed in the ferrule, the optical fiber is not damaged and the optical transmission characteristics are not deteriorated, and the reliability can be improved.

  Further, in the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a light receiving element cut-out flat portion and an exposure cut-out flat portion covering the side surface of the optical fiber in the portion where the fiber grating is formed are formed. Because it includes a glass ferrule, a light receiving element that receives radiation emitted from the side of the optical fiber in the part where the fiber grating is formed, and a substrate on which the light receiving element is mounted, the mechanical strength of the ferrule is significantly reduced. Therefore, it is not necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity with respect to transmitted / received light, and it is possible to avoid the damage of the wavelength filter and the decrease in the yield of manufacturing the optical module. Further, since the optical fiber is not exposed in the ferrule, the optical fiber is not damaged and the optical transmission characteristics are not deteriorated, and the reliability can be increased.

  Further, in the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a glass ferrule in which a notch flat portion for a light receiving element that covers a side surface of the optical fiber in a portion where the fiber grating is formed, In a method of manufacturing an optical module including a light receiving element that receives radiation emitted from the side surface of an optical fiber in a portion where a fiber grating is formed, and a substrate on which the light receiving element is mounted, a refraction equivalent to that of a glass ferrule A glass ferrule is immersed in a transparent container containing a refractive index adjusting liquid having a refractive index, and an ultraviolet irradiation image of a fiber grating forming mask is formed on the optical fiber through the transparent container by a lens to form a fiber grating. The ferrule mechanical strength is significantly reduced. Let not, there is no need to form a fine groove to ensure excess transmission loss and wavelength selectivity to receive light, that yield of the optical module produced decreases wavelength filter is broken can be avoided. In addition, the fiber grating portion can be easily formed (claim 8).

  Further, in the present invention, an optical fiber in which a fiber grating having a radiation mode is formed, and a light receiving element cut-out flat portion and an exposure cut-out flat portion covering the side surface of the optical fiber in the portion where the fiber grating is formed are formed. In a method for producing an optical module, comprising: a glass ferrule; a light receiving element that receives radiation emitted from a side surface of an optical fiber in a portion where the fiber grating is formed; and a substrate on which the light receiving element is mounted. It has a step of forming a fiber grating by forming an ultraviolet irradiation image of the forming mask on the optical fiber through the exposure notch flat portion with a lens, so that the mechanical strength of the ferrule is not significantly reduced, and excessive transmission loss with respect to transmitted and received light And the need to form precise grooves to ensure wavelength selectivity Without that the wavelength filter is lowered yield of the optical module manufactured damaged, it can be avoided. In addition, the fiber grating portion can be easily formed (claim 9).

<First Embodiment>
Hereinafter, an optical module according to a first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 12. FIG. 1 is a perspective view of a ferrule constituting the optical module according to the first embodiment of the present invention, and FIG. 2 is a schematic central portion of FIG. 1 of the optical module according to the first embodiment of the present invention. FIG. FIG. 12 is a diagram for explaining the light emission angle of the received light in the fiber grating of the optical module according to the first embodiment of the present invention. In addition, the oblique line which shows the fiber grating part 7 of FIG. 1 does not show a cross section. The same applies to FIGS. 3, 6, and 9 to be described later. As shown in FIG. 2, the optical module includes an optical fiber 2 in which a fiber grating portion 7 is formed. FIG. 2 shows received light 11 and transmitted light 13 propagating in the optical fiber 2 and radiated light 12 emitted from the fiber grating section 7. Elements that are the same as or correspond to those in FIG. 14 are given the same reference numerals, and descriptions thereof are omitted.

  The ferrule 1 is formed with a light receiving element cut-out flat portion 5 by cutting. The light receiving element notch flat portion 5 is formed so as to expose the side surface of the optical fiber 2. As the ferrule 1, for example, zirconia suitable for precision machining can be used as a material. The optical fiber 2 is made of a material whose refractive index changes when irradiated with ultraviolet rays. For example, a fiber in which a quartz fiber doped with germanium is immersed in pressurized hydrogen to increase ultraviolet sensitivity can be used. . The fiber grating portion 7 is formed by bringing a fiber grating forming mask (not shown) into close contact with the optical fiber 2 and, for example, irradiating the optical fiber 2 with ultraviolet laser light from an excimer laser through the fiber grating forming mask. By this irradiation, the optical fiber 2 changes in refractive index, and the fiber grating portion 7 having a spatial refractive index distribution is formed.

  By the above forming method, the fiber grating portion 7 is formed so as to have the positional relationship shown in FIG. That is, on the optical axis on the plane that includes the optical axis of the optical fiber 2 and the center point of the light receiving surface of the light receiving element 9, the perpendicular to the optical axis of the optical fiber 2 from the center point of the light receiving surface of the light receiving element 9. , The distance on the optical axis of the optical fiber 2 with respect to this reference point is z, and the light emission angle to the center point of the light receiving surface of the light receiving element 9 with respect to the optical axis of the optical fiber 2 of the fiber grating portion 7 Is defined as θ, and the vertical distance between the center of the light receiving surface of the light receiving element 9 and the optical fiber 2 is h, the fiber grating portion 7 is formed so as to satisfy the following formula (1) with respect to the received light 11 To do.

  z = h / tanθ (1)

  After the fiber grating portion 7 is formed, the optical fiber 2 is inserted into a hole for holding the optical fiber formed by excavation with respect to the ferrule 1, and the fiber grating portion 7 is formed on the notch flat portion 5 for the light receiving element. And the direction of the radiated light 12 from the fiber grating portion 7 is on the light receiving element 9 side, and is fixed to the ferrule 1 with an adhesive (not shown). The light receiving element 9 is electrically connected to an electrode (not shown) on the substrate 8 and is mechanically bonded and fixed to the substrate 8. The substrate 8 on which the light receiving element 9 is mounted is adjusted in position so that the emitted light 12 is coupled to the light receiving element 9 while maintaining a predetermined distance from the ferrule 1 on the notch flat portion 5 for the light receiving element. The adhesive 10 is bonded and fixed. As the optical adhesive 10, either epoxy type or acrylic type can be used.

  Next, the operation of light propagating in the optical fiber 2 of the optical module according to the first embodiment will be described with reference to FIGS. 1, 2, and 12. Note that the received light 11 and the transmitted light 13 described below are originally propagated in the optical fiber 2, but the arrows indicating the received light 11 and the transmitted light 13 in FIG. It has not been. The received light 11 incident on the first optical fiber end face 3 of the optical fiber 2 propagates through the optical fiber 2 and reaches the fiber grating section 7. The received light 11 is selectively diffracted by the fiber grating 7 and is emitted to the outside of the optical fiber 2 as emitted light 12 at a light emission angle θ. The emitted light 12 propagates through the optical adhesive 10 and enters the light receiving element 9, where it is converted into an electrical signal. On the other hand, the transmission light 13 generated by a light source (not shown) having a wavelength different from the wavelength of the reception light 11 and incident on the second optical fiber end surface 4 of the optical fiber 2 is transmitted through the fiber grating portion 7 without being subjected to diffraction action. Then, it reaches the first optical fiber end face 3.

  As described above, in the first embodiment, at least a part of the side surface of the optical fiber 2 in which the fiber grating portion 7 having the radiation mode is formed and the portion of the optical fiber 2 in which the fiber grating portion 7 is formed is exposed. The ferrule 1 in which the notch flat part 5 for the light receiving element is formed, the light receiving element 9 for receiving the radiated light 12 emitted from the side surface of the optical fiber 2 in the part in which the fiber grating part 7 is formed, and the light receiving element 9 are mounted. Since the mechanical strength of the ferrule 1 is not significantly reduced, it is not necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity for transmitted / received light, and the wavelength filter. It can be avoided that the yield of the optical module is reduced due to damage. Further, by changing the light emission angle at the position of each fiber grating portion 7 on the optical fiber optical axis, the radiated light 12 at the position of each fiber grating portion 7 is emitted toward the light receiving element 9. The optical coupling efficiency between the light 12 and the light receiving element 9 can be increased.

  In the first embodiment, the configuration using zirconia as the material of the ferrule 1 has been described. However, the configuration using glass, metal, resin, or the like as the material of the ferrule 1 can be similarly implemented. .

<Second Embodiment>
Next, an optical module and an optical module manufacturing method according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a perspective view of a ferrule constituting an optical module according to the second embodiment of the present invention, and FIG. 4 is a schematic central portion of FIG. 3 of the optical module according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view, and FIG. 5 is a view for explaining a fiber grating forming method for an optical module according to the second embodiment of the present invention, and is a cross-sectional view seen in the direction of the arrow of the dashed line AB in FIG. 3 to 5, the optical module according to the second embodiment includes an exposure notch flat portion 6 in addition to the configuration of the optical module according to the first embodiment. Further, FIG. 5 shows a fiber grating forming mask 14 and ultraviolet light 15. Elements that are the same as or correspond to the elements in FIG. 1 and FIG.

  For the ferrule 1, zirconia is used as the material as in the first embodiment. In the ferrule 1, a light receiving element cut-out flat portion 5 and an exposure cut-out flat portion 6 are formed by cutting so that the side surface of the optical fiber 2 is exposed. The exposure notch flat part 6 is formed to be perpendicular to the light receiving element notch flat part 5. Before the fiber grating portion 7 is formed, the optical fiber 2 is inserted into the hole for holding the optical fiber of the ferrule 1 formed by excavation, and is fixed to the ferrule 1 with an adhesive (not shown).

  Next, a method for forming the fiber grating portion 7 will be described with reference to FIG. A fiber grating forming mask 14 is brought into close contact with the optical fiber 2 exposed on the exposure notch flat portion 6 of the ferrule 1, and ultraviolet light 15 such as ultraviolet laser light from an excimer laser is applied to the fiber grating forming mask 14. The optical fiber 2 is irradiated through. By this irradiation, the optical fiber 2 changes in refractive index, and the fiber grating portion 7 having a spatial refractive index distribution is formed.

  By the formation method as described above, the fiber grating portion 7 is formed so as to have the same positional relationship as in the first embodiment. That is, on the optical axis on the plane that includes the optical axis of the optical fiber 2 and the center point of the light receiving surface of the light receiving element 9, the perpendicular to the optical axis of the optical fiber 2 from the center point of the light receiving surface of the light receiving element 9. , The distance on the optical axis of the optical fiber with respect to this reference point is z, and the light emission angle to the center point of the light receiving surface of the light receiving element 9 with respect to the optical axis of the optical fiber 2 of the fiber grating section 7 is When the vertical distance between the center of the light receiving surface of the light receiving element 9 and the optical fiber 2 is h, the fiber grating portion 7 is formed so as to satisfy the above formula (1) with respect to the received light 11. . Note that the operation of light propagating in the optical fiber 2 of the optical module according to the second embodiment is the same as that of the first embodiment, and thus description thereof is omitted.

  As described above, in the second embodiment, at least a part of the side surface of the optical fiber 2 in which the fiber grating part 7 having the radiation mode is formed and the part of the optical fiber 2 in which the fiber grating part 7 is formed is exposed. A ferrule 1 in which the light receiving element cut-out flat portion 5 and the exposure cut-out flat portion 6 are formed, and a light receiving element 9 that receives the emitted light 12 emitted from the side surface of the optical fiber 2 in the portion where the fiber grating portion 7 is formed. And a substrate 8 on which the light receiving element 9 is mounted, so that a precise groove for ensuring excessive transmission loss and wavelength selectivity with respect to transmission / reception light without significantly reducing the mechanical strength of the ferrule 1 is formed. Therefore, it is possible to prevent the wavelength filter from being damaged and the optical module manufacturing yield from being lowered. Further, by changing the light emission angle at each position of the fiber grating portion 7 on the optical fiber optical axis, the emitted light 12 at each position of the fiber grating portion 7 is emitted toward the light receiving element 9, and thus the emitted light 12. And the light coupling element 9 can be improved in optical coupling efficiency.

  Further, by irradiating the optical fiber 2 with the ultraviolet light 15 through the fiber grating forming mask 14, the fiber grating portion 7 can be easily formed, and the radiation direction of the radiation light 12 can be easily controlled. In the second embodiment of the present invention, the configuration using zirconia as the material of the ferrule 1 has been described. However, the configuration using glass, metal, resin, or the like as the material of the ferrule 1 can be similarly implemented. It is.

<Third Embodiment>
Next, an optical module and an optical module manufacturing method according to the third embodiment of the present invention will be described with reference to FIGS. 6 to 8 and FIG. FIG. 6 is a perspective view of a ferrule constituting an optical module according to the third embodiment of the present invention, and FIG. 7 is a schematic central portion of FIG. 6 of the optical module according to the third embodiment of the present invention. FIG. 8 is a cross-sectional view, and FIG. 8 is a view for explaining the fiber grating forming method of the optical module according to the third embodiment of the present invention, and is a cross-sectional view seen in the direction of the arrow of the dashed line AB in FIG. FIG. 13 is a view for explaining the light emission angle of the received light in the fiber grating of the optical module according to the third embodiment of the present invention. FIG. 8 shows an exposure lens 16 that forms an ultraviolet irradiation image of the fiber grating forming mask 14 on the optical fiber 2 through the exposure notch flat portion 6. Elements that are the same as or correspond to the elements in FIGS. 1 to 5 and 12 are given the same reference numerals, and descriptions thereof are omitted.

  In the third embodiment of the present invention, a glass ferrule made of a glass material that transmits ultraviolet rays is used for the ferrule 1. The ferrule 1 is formed with a cutout flat portion 5 for light receiving element and a flat cutout portion 6 for exposure so that the side surface of the optical fiber 2 is not exposed. The exposure notch flat part 6 is formed to be perpendicular to the light receiving element notch flat part 5. Before the grating portion 7 is formed, the optical fiber 2 is inserted into the hole for holding the optical fiber of the ferrule 1 formed by excavation, and is fixed to the ferrule 1 with an adhesive (not shown).

  Next, a method for forming the fiber grating portion 7 will be described with reference to FIG. An ultraviolet light 15 such as an ultraviolet laser beam from an excimer laser is irradiated onto the fiber grating forming mask 14 placed in parallel with the exposure notch flat portion 6 of the ferrule 1. An ultraviolet irradiation image of the fiber grating forming mask 14 by this irradiation is formed on the optical fiber 2 through the exposure lens 16 and the notch flat portion 6 for exposure. As a result, the optical fiber 2 changes in refractive index, and the fiber grating portion 7 having a spatial refractive index distribution is formed.

  By the forming method as described above, the fiber grating portion 7 is formed so as to have the positional relationship shown in FIG. That is, on the optical axis on the plane that includes the optical axis of the optical fiber 2 and the center point of the light receiving surface of the light receiving element 9, the perpendicular to the optical axis of the optical fiber 2 from the center point of the light receiving surface of the light receiving element 9. , The distance on the optical axis of the optical fiber with respect to this reference point is z, and the light emission angle to the flat surface of the notch flat portion 5 for the light receiving element with respect to the optical axis of the optical fiber 2 of the fiber grating portion 7 Is the vertical distance between the flat surface of the light receiving element cutout flat portion 5 of the ferrule 1 and the optical fiber 2, and the center point of the light receiving surface of the light receiving element 9 and the flat surface of the light receiving element cutout flat portion 5 are , And the refractive index of the ferrule 1 is n1, and the refractive index of the optical adhesive 10 between the center of the light receiving surface of the light receiving element 9 and the flat surface of the notched flat portion 5 for the light receiving element is n2. The following equation for the received light 11 Forming a fiber grating 7 that satisfies 2).

  z = (h1 / tan θ) + [h2 × tan {sin−1 ((n1 / n2) × cos θ)}] (2)

  Next, the operation of light propagating in the optical fiber 2 of the optical module according to the third embodiment will be described with reference to FIGS. 6 to 8 and FIG. The received light 11 and the transmitted light 13 described below are originally propagated in the optical fiber 2, but the arrows indicating the received light 11 and the transmitted light 13 in FIG. It has not been. The received light 11 incident on the first optical fiber end face 3 of the optical fiber 2 propagates through the optical fiber 2 and reaches the fiber grating section 7. The received light 11 is selectively diffracted by the fiber grating 7 and is emitted to the outside of the optical fiber 2 as emitted light 12 at a light emission angle θ. The radiated light 12 propagates through the ferrule 1, is refracted at the interface between the flat surface of the light receiving element notch flat portion 5 and the optical adhesive 10, then propagates through the optical adhesive 10 and enters the light receiving element 9. Then, the light receiving element 9 converts it into an electrical signal. On the other hand, the transmission light 13 generated by a light source (not shown) having a wavelength different from the wavelength of the reception light 11 and incident on the second optical fiber end surface 4 of the optical fiber 2 is transmitted through the fiber grating portion 7 without being subjected to diffraction action. Then, it reaches the first optical fiber end face 3.

  As described above, in the third embodiment, the optical fiber 2 in which the fiber grating portion 7 having the radiation mode is formed, and the notch flat for the light receiving element that covers the side surface of the optical fiber 2 in the portion in which the fiber grating portion 7 is formed. A glass ferrule 1 on which a portion 5 and a notch flat portion 6 for exposure are formed, a light receiving element 9 for receiving radiated light 12 emitted from the side surface of the optical fiber 2 in a portion where the fiber grating portion 7 is formed, and Since it is configured to include the substrate 8 on which the light receiving element 9 is mounted, it is necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity for transmitted / received light without significantly reducing the mechanical strength of the ferrule 1. Therefore, it can be avoided that the wavelength filter is damaged and the yield of manufacturing the optical module is lowered. Further, by changing the light emission angle at the position of each fiber grating section 7 on the optical fiber optical axis, the emitted light 12 at the position of each fiber grating section 7 is emitted toward the light receiving element 9. The optical coupling efficiency between the light 12 and the light receiving element 9 can be increased.

  Further, the fiber grating portion 7 can be easily formed by forming an ultraviolet irradiation image of the fiber grating forming mask 14 on the optical fiber 2 fixed to the ferrule 1 through the exposure lens 16 and the exposure notch flat portion 6. The control of the radiation direction of the radiation light 12 can be facilitated. Further, since the optical fiber 2 is not exposed in the ferrule 1, the optical fiber 2 is not damaged and the optical transmission characteristics are not deteriorated, and a highly reliable optical module can be realized.

<Fourth embodiment>
Next, an optical module and an optical module manufacturing method according to the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a perspective view of a ferrule constituting an optical module according to the fourth embodiment of the present invention, and FIG. 10 is a schematic central portion of FIG. 9 of the optical module according to the fourth embodiment of the present invention. FIG. 11 is a cross-sectional view, and FIG. 11 is a view for explaining the fiber grating forming method of the optical module according to the fourth embodiment of the present invention, and is a cross-sectional view seen in the direction of the arrow of the dashed line AB in FIG. FIG. 11 shows a transparent container 17 used when forming a fiber grating portion 7 to be described later and a refractive index adjusting liquid 18 put in the transparent container 17. Elements that are the same as or correspond to the elements in FIGS. 1 to 8 and 13 are denoted by the same reference numerals, and description thereof is omitted.

  In the fourth embodiment of the present invention, a glass ferrule made of a glass material that transmits ultraviolet rays is used for the ferrule 1. The ferrule 1 is formed with a cut-out flat portion 5 for light receiving element by cutting so that the side surface of the optical fiber 2 is not exposed. Before the fiber grating portion 7 is formed, the optical fiber 2 is inserted into the hole for holding the optical fiber of the ferrule 1 formed by excavation, and is fixed to the ferrule 1 with an adhesive (not shown). Further, as the transparent container 17, for example, a glass material having at least one plane that transmits ultraviolet rays can be used. A refractive index adjusting liquid 18 having the same refractive index as that of the ferrule 1 is placed in the transparent container 17. When forming the fiber grating portion 7, the ferrule 1 is immersed in the refractive index adjusting liquid 18 in the transparent container 17.

  Next, a method for forming the fiber grating portion 7 will be described with reference to FIG. First, the ferrule 1 is immersed so that the entire ferrule 1 is covered by the refractive index adjusting liquid 18 placed in the transparent container 17. At this time, the ferrule 1 is arranged so that one of the flat surfaces of the transparent container 17 is perpendicular to the surface of the light receiving element cutout flat portion 5. A fiber grating forming mask 14 is placed parallel to the plane of the transparent container 17, and an ultraviolet light 15 such as an ultraviolet laser beam from an excimer laser is irradiated to the fiber grating forming mask 14. An ultraviolet irradiation image of the fiber grating forming mask 14 by this irradiation is formed on the optical fiber 2 through the exposure lens 16, the plane of the transparent container 17, the refractive index adjusting liquid 18, and the side surface of the ferrule 1. As a result, the optical fiber 2 changes in refractive index, and the fiber grating portion 7 having a spatial refractive index distribution is formed.

  By the formation method as described above, the fiber grating portion 7 is formed so as to have the same positional relationship as in the third embodiment. That is, on the optical axis on the plane that includes the optical axis of the optical fiber 2 and the center point of the light receiving surface of the light receiving element 9, the perpendicular to the optical axis of the optical fiber 2 from the center point of the light receiving surface of the light receiving element 9. , The distance on the optical axis of the optical fiber with respect to this reference point is z, and the light emission angle to the flat surface of the notch flat portion 5 for the light receiving element with respect to the optical axis of the optical fiber 2 of the fiber grating portion 7 Is the vertical distance between the flat surface of the light receiving element cutout flat portion 5 of the ferrule 1 and the optical fiber 2, and the center point of the light receiving surface of the light receiving element 9 and the flat surface of the light receiving element cutout flat portion 5 are , And the refractive index of the ferrule 1 is n1, and the refractive index of the optical adhesive 10 between the center of the light receiving surface of the light receiving element 9 and the flat surface of the notched flat portion 5 for the light receiving element is n2. The above formula for the received light 11 Forming a fiber grating 7 that satisfies 2). Note that the operation of light propagating in the optical fiber 2 of the optical module according to the fourth embodiment is the same as that of the third embodiment, and thus the description thereof is omitted.

  As described above, in the fourth embodiment, the optical fiber 2 in which the fiber grating portion 7 having the radiation mode is formed, and the notch flat for the light receiving element that covers the side surface of the optical fiber 2 in the portion in which the fiber grating portion 7 is formed. The light receiving element 9 for receiving the radiated light 12 emitted from the side surface of the optical fiber 2 in the portion where the fiber grating part 7 is formed, and the light receiving element 9 are mounted. Since the structure including the substrate 8 is used, the mechanical strength of the ferrule 1 is not significantly reduced, it is not necessary to form a precise groove for ensuring excessive transmission loss and wavelength selectivity for transmitted / received light, and the wavelength filter is damaged. Thus, it is possible to avoid a decrease in the yield of manufacturing the optical module. Further, by changing the light emission angle at the position of each fiber grating section 7 on the optical fiber optical axis, the emitted light 12 at the position of each fiber grating section 7 is emitted toward the light receiving element 9. The optical coupling efficiency between the light 12 and the light receiving element 9 can be increased.

  Further, the ferrule 1 is immersed in a refractive index adjusting liquid 18 placed in a transparent container 17 having at least one flat surface, and the ultraviolet irradiation image of the fiber grating forming mask 14 is converted into the plane of the exposure lens 16 and the transparent container 17 and the refractive state. By forming an image on the optical fiber 2 through the rate adjusting liquid 18 and the side surface of the ferrule 1, the fiber grating portion 7 can be easily formed, and the control of the radiation direction of the radiation light 12 can be facilitated. Further, since the optical fiber 2 is not exposed in the ferrule 1, the optical fiber 1 is not damaged and the optical transmission characteristics are not deteriorated, and a highly reliable optical module can be realized.

  The optical module and the optical module manufacturing method according to the present invention do not significantly reduce the mechanical strength of the ferrule, and do not need to form a precise groove for ensuring excessive transmission loss and wavelength selectivity with respect to transmitted / received light. It can be avoided that the yield of the optical module is reduced due to damage to the optical module, and is useful for an optical module for optical communication, an optical module manufacturing method, and the like.

The perspective view of the ferrule which comprises the optical module which concerns on the 1st Embodiment of this invention Sectional drawing in the approximate center part of FIG. 1 of the optical module which concerns on the 1st Embodiment of this invention The perspective view of the ferrule which comprises the optical module which concerns on the 2nd Embodiment of this invention Sectional drawing in the approximate center part of FIG. 3 of the optical module which concerns on the 2nd Embodiment of this invention. The figure for demonstrating the fiber grating formation method of the optical module which concerns on the 2nd Embodiment of this invention The perspective view of the ferrule which comprises the optical module which concerns on the 3rd Embodiment of this invention Sectional drawing in the approximate center part of FIG. 6 of the optical module which concerns on the 3rd Embodiment of this invention. The figure for demonstrating the fiber grating formation method of the optical module which concerns on the 3rd Embodiment of this invention The perspective view of the ferrule which comprises the optical module which concerns on the 4th Embodiment of this invention Sectional drawing in the approximate center part of FIG. 9 of the optical module which concerns on the 4th Embodiment of this invention. The figure for demonstrating the fiber grating formation method of the optical module which concerns on the 4th Embodiment of this invention The figure for demonstrating the light radiation angle of the received light in the fiber grating of the optical module which concerns on the 1st Embodiment of this invention The figure for demonstrating the light radiation angle of the received light in the fiber grating of the optical module which concerns on the 3rd Embodiment of this invention Sectional view of a conventional optical module

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ferrule 2 Optical fiber 3, 31 1st optical fiber end surface 4, 32 2nd optical fiber end surface 5 Notch flat part for light receiving elements 6 Notch flat part for exposure 7 Fiber grating part 8 Substrate 9 Light receiving element 10 Optical adhesive 11 Received light DESCRIPTION OF SYMBOLS 12 Radiation light 13 Transmission light 14 Fiber grating formation mask 15 Ultraviolet light 16 Exposure lens 17 Transparent container 18 Refractive index adjustment liquid 21 1st optical fiber 22 2nd optical fiber 33 Filter insertion groove 34 Wavelength filter

Claims (9)

An optical fiber formed with a fiber grating having a radiation mode;
A ferrule formed with a notched flat part for a light receiving element that exposes at least a part of a side surface of the optical fiber of the part where the fiber grating is formed;
A light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed;
A substrate on which the light receiving element is mounted;
Optical module provided. An optical fiber formed with a fiber grating having a radiation mode;
A ferrule on which a notch flat portion for light receiving element and a notch flat portion for exposure are formed to expose at least a part of a side surface of the optical fiber in a portion where the fiber grating is formed;
A light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed;
A substrate on which the light receiving element is mounted;
Optical module provided. On a plane including the optical axis of the optical fiber and the center point of the light receiving surface of the light receiving element,
A distance on the optical axis of the optical fiber with respect to the reference point is defined as an intersection point on the optical axis perpendicular to the optical axis of the optical fiber from the center point of the light receiving surface of the light receiving element. age,
The light emission angle to the center point of the light receiving surface of the light receiving element with respect to the optical axis of the optical fiber of the fiber grating is θ,
When the vertical distance between the center point of the light receiving surface of the light receiving element and the optical fiber is h,
z = h / tanθ
The optical module according to claim 1 or 2, wherein: An optical fiber in which a fiber grating having a radiation mode is formed, and a light receiving element cut-out flat portion and an exposure cut-out flat portion that expose at least a part of a side surface of the optical fiber of the portion in which the fiber grating is formed are formed. In a method of manufacturing an optical module comprising: a ferrule; a light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed; and a substrate on which the light receiving element is mounted.
Adhering a fiber grating forming mask to the optical fiber exposed on the exposure notch flat part; and
Irradiating the optical fiber with ultraviolet light through the fiber grating forming mask to form the fiber grating; and
An optical module manufacturing method characterized by comprising: An optical fiber formed with a fiber grating having a radiation mode;
A ferrule made of glass in which a notch flat portion for a light receiving element that covers a side surface of the optical fiber in a portion where the fiber grating is formed;
A light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed;
A substrate on which the light receiving element is mounted;
Optical module provided. An optical fiber formed with a fiber grating having a radiation mode;
A glass ferrule on which a notch flat part for a light receiving element and a notch flat part for exposure covering the side surface of the optical fiber of the part where the fiber grating is formed; and
A light receiving element that receives radiation emitted from the side surface of the optical fiber in a portion where the fiber grating is formed;
A substrate on which the light receiving element is mounted;
Optical module provided. On a plane including the optical axis of the optical fiber and the center point of the light receiving surface of the light receiving element,
A distance on the optical axis of the optical fiber with respect to the reference point is defined as an intersection point on the optical axis perpendicular to the optical axis of the optical fiber from the center point of the light receiving surface of the light receiving element. age,
The light emission angle to the flat surface of the notch flat portion for the light receiving element with respect to the optical axis of the optical fiber of the fiber grating is θ,
A vertical distance between the flat surface of the notch flat portion for the light receiving element and the optical fiber is h1,
The refractive index of the glass ferrule is n1,
The vertical distance between the center point of the light receiving surface of the light receiving element and the flat surface of the notched flat portion for the light receiving element is h2,
When the refractive index between the light receiving surface of the light receiving element and the flat surface of the notched flat portion for the light receiving element is n2,
z = (h1 / tan θ) + [h2 × tan {sin−1 ((n1 / n2) × cos θ)}]
The optical module according to claim 5 or 6, wherein: An optical fiber in which a fiber grating having a radiation mode is formed; a glass ferrule in which a notch flat portion for a light receiving element that covers a side surface of the optical fiber in a portion in which the fiber grating is formed; and the fiber grating In a method of manufacturing an optical module comprising a light receiving element that receives radiated light emitted from the side surface of the formed optical fiber and a substrate on which the light receiving element is mounted,
Immersing the glass ferrule in a transparent container containing a refractive index adjusting liquid having a refractive index equivalent to that of the glass ferrule;
Forming a fiber grating by forming an ultraviolet irradiation image of a fiber grating forming mask on the optical fiber through the transparent container with a lens; and
An optical module manufacturing method characterized by comprising: An optical fiber in which a fiber grating having a radiation mode is formed, and a glass ferrule in which a notch flat part for light receiving element and a notch flat part for exposure covering the side surface of the optical fiber of the part where the fiber grating is formed are formed. In a method of manufacturing an optical module comprising: a light receiving element that receives radiated light emitted from the side surface of the optical fiber in a portion where the fiber grating is formed; and a substrate on which the light receiving element is mounted.
An optical module manufacturing method, comprising: forming an optical image of an ultraviolet ray of a fiber grating forming mask on the optical fiber by a lens through the exposure notch flat portion to form the fiber grating.

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