JPH02115810A - Optical module and production thereof - Google Patents

Abstract

PURPOSE:To prevent the damage of an LED and to allow the access to the close distance of an optical fiber so that high-efficiency optical coupling is realized and productivity is improved by limiting a ferrule at the top end of a spacer thicker than the LED and bringing the ferrule near to the LED. CONSTITUTION:The front surface of the spacer 27 provided in proximity to the LED 23 disposed on a substrate 21 consists of a conductive material 29, such as metal, and is set slightly higher than the front surface of the LED 23 or a bonding wire connected to an LED electrode. The ferrule 25 with which the optical fiber 24 is covered is aligned nearly in the central axis to the LED 23 and is lowered until the ferrule comes into contact with the surface electrode 29 of the spacer 27, by which the positioning in the Z direction is executed. Namely, a sleeve 26 is lowered while the conduction of the sleeve 26 and the spacer 27 is kept monitored by an ammeter 28. The sleeve 26 is fixed where the sleeve comes into contact with the spacer 27 and the ammeter 28 operates. The danger of bringing the optical fiber 24 and the LED 23 too close to each other and the consequent failure of the LED 23 is eliminated in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical module used for transmitting and receiving optical communications, etc., and a method for manufacturing the same.

[Conventional technology]

Optical communications require high performance passive and active devices such as optical fibers, semiconductor lasers (LDs), light emitting diodes (LEDs), and photodiodes (PDs), as well as optical switches, optical modulators, isolators, and optical waveguides. The range of applications is expanding due to higher functionality. In optical communication systems, optical elements such as light emitting and light receiving elements are not used alone, but are usually used in the form of modules integrated with optical fibers. Optical coupling between an optical element and a fiber is roughly divided into lens coupling via a lens and direct coupling without a lens.

Direct coupling is used in multimode systems and modules where low cost is required.

Figure 2 shows a typical direct-coupled optical module, with the center cut out so that the internal elements can be seen. A submount 22 made of Si or AIN that also serves as a heat sink is installed approximately at the center of the Cu or CuW substrate 21 .

The surface of the submount 22 forms an electrode pattern, and the LE
It is fused to the electrode of D23. A cylindrical sleeve 26 is fixed on the substrate 21 as a connection part to the optical fiber so that the central axis is substantially the same as that of the LED 23. The optical fiber 24 protected by the metal ferrule 25 is fixed to the sleeve 26 by adhesive, solder, or welding after adjusting the optical axis in the x, y, and z directions so that the emitted light from the LED 23 is efficiently incident. Here, in order to avoid optical coupling loss as much as possible, the distance between the LED and the optical fiber is made as small as possible. The ferrule 25 and the sleeve 26 are made of the same material, and 5US304 is usually used.

[Problem to be solved by the invention]

As mentioned above, when directly coupling an optical device such as a light emitting or light receiving device to an optical fiber, it is necessary to reduce the distance between the optical device and the optical fiber in order to reduce the coupling loss, and when the distance is zero, it is the minimum. Become. However, a certain distance is provided to avoid damage to the surface of the optical element and cutting of the bonding wires of the electrodes. Actual optical axis adjustment is performed by monitoring the optical output at the output end of the fiber. Adjust to the position where the optical output is maximum in the x and y force directions (directions parallel to the board surface), but as mentioned above, the optical output increases as the distance between the optical element and the optical fiber becomes smaller. Therefore, it is difficult to find the optimal position and the adjustment process is large. Also, since the position of the optical fiber cannot be seen from the outside, there is a high risk of the optical fiber coming into contact with an optical element or bonding wire and damaging it.
The inclination of the optical fiber cannot be accurately determined.

An object of the present invention is to solve the above-mentioned problems and provide an optical module with low optical coupling loss, high productivity, and low cost, and a method for manufacturing the same.

[Means to solve the problem]

The optical module of the present invention includes an optical element consisting of a light emitting or light receiving element, a substrate for supporting and fixing the optical element, a cylindrical sleeve whose central axis is aligned with the optical element and fixed to the substrate, and the optical element. a ferrule that covers and protects the optical fiber that is directly optically coupled to the optical element, and has at least a conductive tip surface that is fitted and fixed to the sleeve; A spacer whose upper surface is partially conductive is provided in contact with the end surface of the ferrule around the optical element and on the surface of the substrate inside the sleeve.

Further, the method for manufacturing the optical module includes a manufacturing process in which the conductive portions of the ferrule and the spacer are used as electrodes, and the ferrule is inserted into the spacer and moved to a position where the two electrodes are electrically connected and fixed. are taken.

(Function) In the optical module of the present invention, when the ferrule is brought close to the LED, it is restricted by the upper end of the spacer which is thicker than the LED, so the optical fiber can be brought close to the LED without damaging it. As a result, highly efficient optical coupling can be achieved.

Optical axis adjustment in the optical axis direction (Z) can be accomplished by simply moving the ferrule until it comes into contact with the spacer. Therefore, it is possible to reduce man-hours and improve productivity.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1(A) is an example of a module showing the present invention, and FIG. 1(B) is a sectional view thereof.

A 1 mm square submount 22 made of Si, for example, 0.5 mm thick and 1 mm square, which also serves as a heat sink, is fixed approximately at the center of a substrate 21 made of Cu or CuW, and a submount 22 with a thickness of 0.5 mm made of Si, for example, is fixed by soldering or the like. A 2 mm x 0.5 mm square LED 23 is soldered and fused. Furthermore, in the vicinity of the LED 23, a material such as metal or semiconductor with a thickness of 0.705 to 2.71 mm,
A 2 mm square spacer 27 is attached to the board 2 using adhesive or solder.
It is fixed on 1. The upper surface of the spacer 27 is made of a conductive material 29 such as metal, and is escaped to a position slightly higher than the upper surface of the LED 23 or the bonding wire connected to the LED electrode. Metal e.g. 5US30
The sleeve 26 made of No. 4 is fixed to the substrate 21 by soldering or brazing with its center axis substantially aligned with the LED 23.

The ferrule 25 covering the optical fiber 24 is 5US30.
It is made of a conductive material such as No. 4, and is brought into contact with the surface electrode 29 of the spacer 27 for alignment in two directions. That is, the sleeve 25 is lowered while monitoring the conduction between the sleeve 25 and the spacer 27 using the ammeter 28, and the spacer 27 is lowered.
When the ammeter 28 is activated by contacting the sleeve 25
This is a method of fixing. The light output from the output end of the optical fiber is monitored in the x and y force directions, and the normal optical axis adjustment is performed by moving the ferrule 25 to maximize it, and the ferrule is fixed at that position by a method such as laser welding or solder welding. . Optical axis adjustment in two directions, which was difficult with the conventional configuration, can be achieved almost without adjustment, and there is no risk of damaging the LED 23 by bringing the optical fiber 24 and the LED 23 too close together.

FIG. 1(C) is a top view of the package part of the optical module, that is, the sleeve fixed to the substrate on which the LED is fixed.
9a, b, c, d). Continuity with the ferrule 25 is monitored for each of the four electrodes, and when all of the four electrodes are in a conductive state, the ferrule 25 no longer tilts. That is, the optical axis of the optical fiber 24 is parallel to the optical axis of the LED 2B, allowing highly efficient optical coupling. Therefore, compared to the conventional structure, it is possible to significantly reduce the number of man-hours and improve productivity.

In this example, an LED is shown as an optical element, but LD, PD
But it's the same. Further, the spacer 27 may have other shapes, such as a cylindrical shape, a cylindrical shape whose central axis is substantially the same as that of the LED, or a prismatic cylindrical shape.

Further, although the spacer electrode is divided into four parts, it may be divided into four parts or more, and the spacer may be made of a conductive material and the divided electrodes may be provided on the ferrule side.

〔Effect of the invention〕

As explained above, according to the present invention, an optical module with small optical coupling loss can be realized, and the optical module can be manufactured with high productivity and at low cost.

[Brief explanation of drawings]

FIGS. 1A, 1B, and 1C are block diagrams showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional optical module. 21... Board, 22... Submount, 23...
LED, 24... Optical fiber, 25... Ferrule, 26... Sleeve, 27... Spacer, 28...
・Ammeter, 29, 29 (a), (b),
(c), (d) - current.

Claims (2)

[Claims] (1) An optical element consisting of a light emitting or light receiving element, a substrate that supports and fixes the optical element, a cylindrical sleeve whose central axis coincides with the optical element and is fixed to the substrate, and a cylindrical sleeve that is directly connected to the optical element. A ferrule is provided to cover and protect the optical fiber to be optically coupled, and has at least a conductive tip surface that is fitted and fixed to the sleeve, and further includes a ferrule that is thicker than the optical element and at least part of the upper surface. An optical module characterized in that a spacer whose portion is electrically conductive is provided in contact with the end face of the ferrule around the optical element and on the surface of the substrate inside the sleeve. (2) Arrange a spacer whose upper surface is conductive at least around the optical element, align the optical axis of the optical element with the center axis of the cylindrical sleeve, and fix the spacer, optical element, and sleeve to the substrate, and then Insert into the sleeve a ferrule that fixes the fiber inside and has at least a conductive tip surface, use the conductive portion of the ferrule and spacer as an electrode, and move the ferrule to a position where the two electrodes are electrically conductive. 1. A method for manufacturing an optical module, characterized in that the optical module is fixed in a fixed position.