JPH0990175A - Optical communication module - Google Patents

Abstract

(57) Abstract: The loss in the circuit portion of a photoelectric conversion element is reduced to prevent deterioration of the code error rate of a transmission signal in a high-speed communication area, and an area for forming an amplifier circuit is secured. The purpose is to combine small photoelectric conversion elements with high accuracy. SOLUTION: The optical fiber 1 is attached to the tip side of a ferrule 10 in which one end of an optical fiber 11 is inserted and fixed in a pore 12.
The circuit board 30 having the through hole 31 exposing the end surface 11a of No. 1 is joined and the tip surface 33 of the circuit board 30 is joined.
Further, the optical communication module 1 is configured by including the photoelectric conversion element 40 so that the light emitting / receiving surface faces the optical fiber end surface 11a.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical communication module for connecting an optical fiber and a photoelectric conversion element.

[0002]

2. Description of the Related Art Conventionally, an optical communication module has been used in which a photoelectric conversion element such as a laser diode or a photodiode and an optical fiber for introducing or leading an optical signal to the photoelectric conversion element are connected. ing.

In the structure of a general optical communication module, a ferrule having an optical fiber inserted and fixed and a package having a photoelectric conversion element enclosed are joined to both ends of a through hole provided in the casing, and a lens is provided inside the casing. Be prepared. However, such an optical communication module is difficult to miniaturize, and it is difficult to accurately align the optical axes of the optical fiber tip and the photoelectric conversion element due to the large distance between them. There was a problem.

Therefore, it has been proposed that an electrode is directly formed on the end face of a ferrule in which one end of an optical fiber is inserted and fixed, and a photoelectric conversion element is mounted on this electrode to form an extremely small optical communication module. (See JP-A-62-178204).

[0005]

However, the optical communication module having the structure in which the photoelectric conversion element is directly attached to the end face of the ferrule has the following problems in coping with the recent improvement in optical communication speed. .

First, as the material of the ferrule, zirconia ceramics of high strength and high toughness are generally used. Since this zirconia ceramics has a high dielectric constant,
There has been a problem that the loss of the high frequency signal in the circuit (electrode) portion formed on the end face becomes large and the code error rate of the transmission signal in the high speed communication region deteriorates.

Further, in the case of transmitting a high-speed signal, it is common to provide a current-voltage amplifier circuit in the vicinity of the photoelectric conversion element and couple it with the photoelectric conversion element through a transmission line with impedance matching. The end surface has a diameter of 2.5 mm
Alternatively, since it is as small as 1.25 mm, there is a problem that it is impossible to secure a region for forming the amplifier circuit and the transmission line.

Further, in order to cope with high-speed signals, a method of reducing the size of the photoelectric conversion element to increase the reaction speed of the element is taken, and therefore the positional accuracy when connecting the elements is important. However, since the ferrule end face is small in the above optical communication module, it is difficult to form the circuit by the thick film or thin film forming means so that the alignment accuracy of the circuit and the end face of the optical fiber is ± 10 μm or less. Therefore, it was not possible to combine the small photoelectric conversion elements with high accuracy.

Further, even if an antireflection film for preventing unnecessary reflection of light is formed on the end face of the optical fiber, there is a problem that the antireflection film is peeled off in the step of forming a circuit on the end face of the ferrule.

[0010]

Therefore, according to the present invention, a ferrule having one end of an optical fiber inserted and fixed in a fine hole is inserted and fixed in a mounting hole of a holding member, and a distal end side of the holding member is fixed.
A circuit board having a through hole through which the end face of the optical fiber is exposed is joined, and a photoelectric conversion element is provided on the surface on the front end side of the circuit board so that the light receiving and emitting surface faces the end face of the optical fiber. It is characterized in that a communication module is configured.

[0011]

According to the present invention, by attaching the photoelectric conversion element to the circuit board provided on the tip side of the ferrule, a material having a low dielectric constant can be used as the circuit board, and the loss in the circuit portion can be reduced. .

Further, since the circuit board can be formed in a desired size, it is possible to secure a sufficient area for forming an amplifier circuit and a transmission line.

Furthermore, the circuit may be formed on a circuit board having a sufficient area, and the circuit board and the ferrule may be joined together while aligning the circuit and the end face of the optical fiber. The alignment accuracy between the circuit and the end surface of the optical fiber can be increased, and the photoelectric conversion element and the optical fiber can be coupled with high accuracy.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, in the optical communication module 1 of the present invention, one end of an optical fiber 11 is inserted and fixed in a pore 12 and the tip side (left side in the drawing) of a ferrule 10 is
The holding member 20 is fixed by being inserted into the mounting hole 21 of the holding member 20.
A circuit board 30 having a through hole 31 exposing the end surface 11a of the optical fiber 11 is bonded to the front end surface 22 of the optical fiber 11, and a circuit 32 is connected to the front end surface 33 on the side opposite to the bonding surface of the circuit board 30.
And the through hole 3 in the tip surface 33.
The photoelectric conversion element 40 is joined to the position where 1 is closed so that its light receiving or emitting surface faces the end surface 11 a of the optical fiber 11.

The photoelectric conversion element 40 is a light emitting element such as a laser diode or a light receiving element such as a photodiode. When the photoelectric conversion element 40 is a light emitting element, the emitted optical signal can be derived by the optical fiber 11, and when the photoelectric conversion element 40 is a light receiving element, the optical signal introduced by the optical fiber 11 can be received. In any case, it can function as an extremely small module for optical communication.

The ferrule 10 is made of ceramics, but is preferably made of zirconia ceramics having particularly high strength and high toughness. The ferrule 10 is provided with a pore 12 penetrating in the axial direction, and one end of the optical fiber 11 is inserted into the pore 12 and fixed with an adhesive or the like. Further, it is preferable that the tip surface 13 of the ferrule 10 is polished so as to be flush with the end surface 11a of the optical fiber 11, and an antireflection film (not shown) is formed on the end surface 11a of the optical fiber 11.

The holding member 20 is made of ceramics having good workability or a resin such as liquid crystal polymer, and has a mounting hole 21 for inserting the ferrule 10 at the center thereof.
It has. The ferrule 10 is inserted into the mounting hole 21, and is joined by an epoxy adhesive or solder at a position where the tip surface 13 of the ferrule 10 and the tip surface 22 of the holding member 20 are substantially flush with each other. The holding member 20
When the resin is formed of resin, it is also possible to mold it around the ferrule 10.

The circuit board 30 is formed of a high frequency circuit material such as alumina ceramics or polyimide amide having a low dielectric constant and excellent electrical characteristics, and has a through hole 31 in the center. Further, the circuit 32 as shown in FIG. 2 is formed on the tip surface 33 on the side opposite to the bonding surface by a thick film or thin film means. However, by using a material having a low dielectric constant for the circuit board 30, the circuit 32 is formed. Loss can be reduced.

When the circuit board 30 is joined to the tip surface 22 of the holding member 20, the end surface 11a of the optical fiber 11 is exposed from the through hole 31 as shown in FIG.
After the position of 1a and the through hole 31 or the circuit 32 are aligned, they are joined by an adhesive or the like. This position adjustment can be easily performed with an accuracy of about several μm by using an image processing device, and the bonding can be performed with extremely high accuracy.

Further, as the circuit board 30, it is also possible to use a ceramic multilayer circuit board or a board in which electric elements are formed.

Then, the photoelectric conversion element 40 may be bonded to the position where the through hole 31 is closed on the tip surface 33 of the circuit board 30. Further, since the circuit board 30 has a sufficient area, an amplifier circuit may be provided in the vicinity of the photoelectric conversion element 40 so that the transmission line can be coupled to the photoelectric conversion element 40.

[0023]

As described above, according to the present invention, the ferrule having one end of the optical fiber inserted and fixed in the pore is inserted and fixed in the mounting hole of the holding member, and the optical fiber is attached to the tip side of the holding member. A circuit board having a through hole whose end face is exposed is joined, and a photoelectric conversion element is provided on a front end side surface of the circuit board so that a light emitting / receiving surface faces the end surface of the optical fiber. By configuring the above, the following effects are achieved.

Since a material having a low dielectric constant can be used for the circuit board, it is possible to reduce loss in the circuit portion of the photoelectric conversion element and prevent deterioration of the code error rate of the transmission signal in the high-speed communication area.

Since the circuit board can be formed to have a desired size, it is possible to provide an amplifier circuit in the vicinity of the photoelectric conversion element and connect the transmission lines with impedance matching.

Since the alignment between the circuit board and the ferrule can be performed easily and with high accuracy, the coupling efficiency between the photoelectric conversion element and the optical fiber can be increased.

Since it is only necessary to bond a circuit board on which a circuit is formed in advance, it is possible to prevent the antireflection film formed on the front end surface of the optical fiber from peeling off.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an optical communication module of the present invention.

FIG. 2 is an end view of the optical communication module of the present invention viewed from the circuit board side.

FIG. 3 is a diagram for explaining alignment of a circuit board in the optical communication module of the present invention.

[Explanation of symbols]

 10: Ferrule 11: Optical fiber 12: Pore 13: Tip surface 20: Holding member 21: Mounting hole 22: Tip surface 30: Circuit board 31: Through hole 32: Circuit 33: Tip surface 40: Photoelectric conversion element

Claims (1)

[Claims] 1. A ferrule in which one end of an optical fiber is inserted and fixed in a fine hole is inserted and fixed in a mounting hole of a holding member, and a through hole for exposing the end face of the optical fiber is provided on the tip side of the holding member. An optical communication module comprising a circuit board and a photoelectric conversion element on the surface of the circuit board such that a light emitting / receiving surface faces the end surface of the optical fiber.