JP3202425B2 - Light receiving module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a light receiving module, and more particularly, to an optical transmission module used for optical communication and the like. For example, it is applied to optical communication, optical information processing, and optical interconnection.

[0002]

2. Description of the Related Art Known literature describing the prior art according to the present invention is "Prototype Production of Multi-Channel LD and PD Array Modules" (Kaoru Moriya, three, 1992 IEICE Spring Conference, C-269, P4- An optical module is proposed in 311). In this document, a PD is mounted on a side surface of an optical element fixing member, arranged via a fiber and a lens fixed on a silicon V-groove, and an optical axis is adjusted using an adjusting and fixing block, and then fixed. The structure has the following structure.

FIG. 5 is a diagram showing a conventional example of an optical module (PD array module) described in the above document.
In the figure, 31 is a carrier, 32 is a lens array, 33 is a tape fiber, 34 is a PD array, 35 is a block for adjusting and fixing, and 36 is a SiV groove fabric aligning member. The fibers 33 are precisely arranged with V grooves formed at equal intervals by anisotropic etching of silicon. The lens array 32 uses a lens array in which micro lenses are monolithically integrated.

The features of this module are as follows. Wide tolerance coupling system; (LD / lens) VS (fiber) adjustment The tolerance characteristic of fixing is significantly improved in both coupling loss and tolerance as compared with direct coupling of LD and fiber. Simple adjustment and fixation: The Z axis (optical axis direction) is not adjusted by using a spacer or the like, and only the X and Y axes are adjusted. Laser welding fixation: The main fixing points are improved in reliability by laser welding.

However, in the conventional optical module as described above, in a configuration in which an optical element and an optical fiber are individually assembled on an adjustment block, it is necessary to perform optical axis adjustment individually for each module. There is a problem that the size itself becomes large.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a high-performance light receiving module that is small and easy to adjust the optical axis.

[0007]

To achieve the above object, the present invention provides (1)
An optical fiber holding member formed with a groove having an optical fiber fixing function and an optical path conversion function, and a light receiving element forming member formed with at least one light receiving element; After the light emitted from the optical fiber is converted into an optical path by a processing surface having a reflection function provided on the optical fiber holding member, a light receiving element forming member whose positional relationship is adjusted so as to efficiently enter the light receiving portion of the light receiving element is arranged. A light receiving module formed by adhering to the optical fiber holding member ;
Using a crystal substrate provided with a light receiving element on a material,
Anisotropic etching for positioning groove for optical fiber positioning
The positioning groove is provided by a light receiving element.
That provided on the terminal side, even (2) the light receiving element forming member providing the light-receiving element using a multilayer crystal substrate, and further, the refractive index to the light receiving surface from the exit end of (3) the optical fiber it was filled with a transparent material that matches the refractive index and the outline of the fiber, and further, is obtained by the features that you using an optical fiber having a lens function (4) end surface. Hereinafter, a description will be given based on examples of the present invention.

FIGS. 1 (a) and 1 (b) are configuration diagrams for explaining an embodiment of a light receiving module according to the present invention, wherein FIG. 1 (a) is a sectional view and FIG. 1 (b) is a plan view. In the figure, 1 is a light receiving module, 2 is an optical fiber holding member, 3 is a light receiving element forming member, 4 is an optical fiber, 5 is a fiber fixing groove,
6 is a reflection surface, 7 is a light receiving element, and 8 is an electrode. The small light receiving module 1 of the present invention comprises at least one or more optical fibers 4, a member 2 having a groove 5 having a fiber fixing function and an optical path changing function, and a light receiving element forming member 3. The light emitting element forming member 3 whose positional relationship is adjusted so that the light emitted from the optical path is converted by the processing surface 6 having a reflecting function provided on the member and has a reflecting function, and then is efficiently incident on the light receiving portion of the light receiving element 7 is accurately arranged. And it has a structure bonded to the optical fiber holding member.

2 (a) to 2 (f) are views for explaining a method of manufacturing the light receiving module, in which 9 is a positioning groove, 10 is a mask opening, 11 is an oxide film, and 12 is a reflection film. Other parts of the membrane that have the same function as in FIG. 1 are denoted by the same reference numerals. In this embodiment, a short-wavelength optical communication module having a light source with a wavelength of 1 μm or less, which can constitute an inexpensive system, will be described. In this embodiment, since the optical fiber fixing groove 5 and the positioning groove on the light receiving element side are formed by etching, an n-type Si
A crystal substrate is used.

First, after forming an oxide film 11 on the crystal surface using steam oxidation or the like, a rectangular mask opening for anisotropic etching is formed in the oxide film 11 by photolithography and etching. The portion 10 is formed (FIG. (A)), and anisotropic etching is performed using an etching solution such as KOH or EPW (ethylenediamine pitecaterol aqueous solution) to produce the optical fiber fixing groove 5 (FIG. (B) )). At this time, by making the mask opening have a predetermined crystal orientation, the angle between the etching surface 6 on the short side and the substrate becomes approximately 55 degrees.

Next, Au is deposited on the substrate by a normal vapor deposition method.
After the reflective film 12 is formed on the etched surface, an oxide film for insulation is formed by sputtering or the like, and the optical fiber 4 is fixed to manufacture the optical fiber holding member 2. On the other hand, the light receiving element forming member 3 is provided with a substantially square opening by photolithography and etching on an n-type Si crystal substrate on which an oxide film is formed by the above-described oxide film forming method, and boron (B) is supplied from the opening. After selectively ion-implanting to form a p-type region 7 to produce a photodiode (PD) (FIG. 4D), an electrode pattern 8 is formed on the front and back surfaces of the substrate to produce a light receiving element forming member 3. (Figure (e)).

At this time, in order to secure the alignment accuracy with the optical fiber holding member 2, the positioning groove 9 is used.
May be formed by the above-described anisotropic etching method using an oxide film as a mask before the electrodes are formed (FIG. (F)). In the light-receiving module according to the present invention, the optical fiber holding member and the light-receiving element forming member are opposed to each other so as to allow the light emitted from the optical fiber to efficiently enter the light-receiving element so as to be bonded together after the position adjustment, and held by bonding or the like. I do.

FIGS. 3A and 3B are diagrams showing another embodiment of the light receiving module according to the present invention, wherein FIG.
FIG. 2B is a plan view. Reference numbers in the figure are the same as those in FIG. In the embodiment shown in FIG. 1, the light receiving module is arranged such that the optical fiber holding member 2 and the light receiving element forming member 3 are aligned after the position adjustment so that the light emitted from the optical fiber efficiently enters the light receiving element. Is held by an adhesive or the like. In this case, when the positioning groove 9 is formed on the light receiving element side, the positioning groove 9 is formed.
Positioning is performed by moving the optical fiber 4 along the path, and the positioning at the time of mounting the light receiving module can be adjusted without adjustment.

FIGS. 4A to 4D show still another embodiment of the light receiving module according to the present invention. In the drawing, reference numeral 21 denotes a spherical optical fiber, 22 denotes a thermosetting transparent resin, and 23 denotes a transparent resin. The multilayer optical thin film 24 is an n-type crystal thin film, and other portions having the same functions as those in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 9A, the outgoing light has directivity by using a spherical optical fiber 21 having a lens function added to the tip of the optical fiber,
As shown in FIG. 2B, the space from the tip of the optical fiber to the light receiving surface is fixed and filled with a thermosetting transparent resin 22 having a refractive index substantially equal to the refractive index of the fiber. It is also possible to suppress the spread of the light beam emitted from the light source.

Also, various configurations are possible for the light receiving element portion. For example, as shown in FIG.
3 to provide an active function such as imparting wavelength selectivity, or as shown in FIG. 3D, an n-type crystal thin film 24 having a lower concentration than i or i-type on the n-type plate surface on the crystal substrate. It is also possible to use a substrate having such a structure and make the PD section a PIN structure to provide a light-receiving element capable of high-speed response. Further, it is also possible to manufacture a long-wavelength light receiving module using an InP crystal substrate as the crystal substrate on the light receiving element side, and to mold the optical fiber holding member to a Si crystal substrate having grooves formed by the anisotropic etching. Alternatively, a substrate in which a reflection surface is formed by a vapor deposition method or the like on a resin substrate on which grooves are transferred using a normal duplication technique may be used.

[0016]

As apparent from the above description, the present invention has the following effects. (1) Effect according to the first aspect: By bonding two functional members together, it is possible to provide a high-performance light receiving module that is small and easy to adjust the optical axis. Ma
In addition, a crystal substrate in which a light receiving element is
Positioning the optical fiber on the crystal substrate
Grooves are provided by anisotropic etching means.
Since the positioning groove is provided on the light receiving element side, each member can be accurately positioned, and the assembly process can be simplified. ( 2 ) Effect corresponding to claim 2 ; each member can be accurately positioned, and the assembly process can be simplified, and a high-performance light receiving element can be provided. . ( 3 ) An effect corresponding to claim 3 ; the divergence angle of the light emitted from the fiber can be reduced together with the reinforcing effect at the time of assembling each member, and the divergence of the light beam on the light receiving surface is suppressed, and the light is efficiently emitted. It is possible to receive a signal. ( 4 ) An effect corresponding to claim 4 ; directivity can be added to light emitted from the optical fiber, and an optical signal can be received efficiently.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a light receiving module according to the present invention.

FIG. 2 is a diagram for explaining a method for manufacturing a light receiving module according to the present invention.

FIG. 3 is a diagram showing another embodiment of the light receiving module according to the present invention.

FIG. 4 is a view showing still another embodiment of the light receiving module according to the present invention.

FIG. 5 is a configuration diagram of a conventional light receiving module.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light receiving module, 2 ... Optical fiber holding member, 3 ... Light receiving element forming member, 4 ... Optical fiber, 5 ... Optical fiber fixing groove, 6 ... Reflection surface, 7 ... Light receiving element, 8 ... Electrode.

Claims (4)

(57) [Claims] An optical fiber holding member having at least one optical fiber, a groove having an optical fiber fixing function and an optical path changing function, and a light receiving element forming member having at least one light receiving element. A light receiving element having an optical path converted by a processing surface having a reflection function provided on the optical fiber holding member for the outgoing light from the optical fiber, and then having a positional relationship adjusted to efficiently enter a light receiving portion of the light receiving element. the forming member is disposed, in the light receiving module configured by laminating and the optical fiber holding member, wherein
Using a crystal substrate provided with a light receiving element on a light receiving element forming member,
Positioning groove for positioning an optical fiber on the crystal substrate
Is provided by anisotropic etching means, and
The receiving groove is provided on the light receiving element side.
Jules. 2. The light receiving module according to claim 1, wherein a light receiving element is provided on the light receiving element forming member using a multilayer crystal substrate. 3. The light receiving module according to claim 1, wherein the optical fiber is filled with a transparent substance having a refractive index substantially equal to the refractive index of the fiber from the emission end of the optical fiber to the light receiving surface. 4. The light receiving module according to claim 1, wherein an optical fiber having a lens function is used for an end face.