JP2001264588A - Laser diode module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laser diode module at a low cost which has stable operation because the reflected light from the optical fiber end face and the returning light from the inner part of the optical fiber do not return to the laser diode. SOLUTION: A V-shape hole is formed in a silicon substrate in such a manner that the lens is arranged with the center of the lens deviated from the optical axis of the laser light in the plane including the optical axis of the laser light on the silicon substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser diode module mainly used for optical fiber communication.

[0002]

2. Description of the Related Art In a laser diode module, which is a key device for optical fiber communication, when reflected light or scattered light from an optical component returns to the laser diode, the operation of the laser diode becomes unstable, resulting in an increase in noise and transmission signal. In some cases, it may be necessary to adopt a structure that does not return reflected return light. FIG.
1A and 1B are a top view and a cross-sectional view of a laser diode module having the same configuration as that of Japanese Patent No. 70772. In the figure, 1
Is a laser diode, 2 is a silicon substrate supporting the laser diode 1, 3 is a lens for condensing the laser light emitted from the laser diode 1, 4 is the center of the lens 3, 5 is
Is a V-shaped hole for supporting a lens 3 formed on the silicon substrate 2 by selective anisotropic etching, and 6 is a lens 3
An optical fiber for coupling the laser light condensed by the laser beam; 7, a V-shaped groove for supporting the optical fiber 6 formed on the silicon substrate 2 by selective anisotropic etching; and 8, a laser light emitted from the laser diode 1. The optical axis 9 is the central axis of the optical fiber 6, and the laser diode 1 is arranged on the upper surface of the silicon substrate at an end surface of the fiber 6 so as to have an angle α at which the laser light of the laser diode 1 is appropriately coupled. Optical axis 8 of laser light emitted from laser diode 1
The lens 3 is arranged so that the lens passes through the center 4 of the lens 3.

In the conventional laser diode module having such a structure, the reflected light returning from the end face of the optical fiber 6 to the laser diode 1 is small, and the laser light emitted from the laser diode 1 is efficiently transmitted to the optical fiber 6. Can be combined.

[0004]

In the laser diode module as described above, in order to efficiently couple the laser light of the laser diode 1 to the optical fiber 6,
It is necessary to arrange the laser diode 1 at an accurate position on the silicon substrate 2 and at an accurate angle within the upper surface of the silicon substrate 2, which makes the production of the laser diode module difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a small amount of laser light returning from an optical fiber to a laser diode, has a high coupling efficiency to an optical fiber, and is easy to assemble. Is what you get.

[0006]

According to a first aspect of the present invention, there is provided a laser diode module in which the center of a lens has a laser beam emitted from a laser diode within a vertical plane of an upper surface of a substrate including an optical axis of the laser beam emitted from the laser diode. It is configured to deviate from the optical axis.

In the laser diode module of the second invention, the center of the lens deviates from the optical axis of the laser light emitted from the laser diode in a vertical plane including the optical axis of the laser light emitted from the laser diode. The optical isolator is arranged between the lens and the optical fiber.

A laser diode module according to a third aspect of the present invention uses a first lens and a second lens for optical coupling between a laser diode and an optical fiber, and the center of the second lens emits laser light emitted from the laser diode. The laser beam emitted from the laser diode deviates from the optical axis of the laser diode within the vertical plane of the upper surface of the substrate including the axis.

A laser diode module according to a fourth aspect of the invention uses a first lens and a second lens for optical coupling between the laser diode and the optical fiber, and the center of the first lens is emitted from the laser diode. The laser beam emitted from the laser diode deviates from the optical axis of the laser diode within the vertical plane of the substrate upper surface including the optical axis of the light.

According to a fifth aspect of the present invention, a laser diode module uses a first lens and a second lens for optical coupling between a laser diode and an optical fiber, and the center of the first lens is a laser beam emitted from the laser diode. An optical isolator is arranged between the first lens and the second lens, deviating from the optical axis of the laser light emitted from the laser diode within a vertical plane of the upper surface of the substrate including the optical axis.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 shows a laser diode module according to Embodiment 1 of the present invention.
In the figure, reference numerals 1 to 9 are the same as those of the conventional apparatus, and thus the description is omitted. The lens 3 is supported by a V-shaped hole 5 such that the center 4 of the lens 3 is shifted downward from the optical axis 8 of the laser diode in the vertical plane of the upper surface of the silicon substrate 2, and the laser light emitted from the laser diode 1 The optical axis 8 is bent downward by an angle α in the vertical plane of the upper surface of the silicon substrate 2 by the lens 3. For example,
The inclination of the optical fiber 6 with respect to the plane perpendicular to the central axis 9 is 8 °
Α is about 3.8 °, and the second lens 1
When the focal length of 0 is 3 mm, the amount of deviation of the center 11 of the second lens 10 from the optical axis 8 of the laser beam for realizing this α is about 0.2 mm. In the laser diode module configured as described above, the optical coupling to the obliquely polished optical fiber 6 can be largely maintained without making the direction of the laser diode 1 oblique in the upper surface of the silicon substrate 2. The laser light reflected from the end face of the optical fiber 6 can be made to travel in a direction not returning to the laser diode 1.

Embodiment 2 FIG. FIG. 2 shows a second embodiment of the present invention, in which 10 is an optical isolator disposed between the lens 3 and the optical fiber 6, and 11 is an optical isolator formed on the silicon substrate 2 by selective anisotropic etching. 10 is a V-shaped hole for placing the first lens 3
Of the laser light emitted from the laser diode 1 in a vertical plane of the upper surface of the silicon substrate 2 including the optical axis 8 of the laser light emitted from the laser diode 1. 2, a V-shaped hole 5 is formed. According to this embodiment, the same effect as in the first embodiment can be obtained, and the laser light returning from inside the optical fiber 6 to the laser diode 1 which causes the unstable operation of the laser diode 1 is attenuated by the optical isolator 10. Can be done. The light reflected by the end face of the optical isolator 10 travels in a direction not to reach the laser diode 1 because the center 4 of the lens 3 is displaced from the optical axis 8 of the laser light.

FIG. 3 shows a third embodiment of the present invention, in which 3 is a first lens, 4 is the center of the first lens, 5 is a first V-shaped hole, 12 is a second lens, Reference numeral 13 denotes a center of the second lens 12, and reference numeral 14 denotes a second V-shaped hole for supporting the second lens 12 formed on the silicon substrate by selective anisotropic etching. The first V-shaped hole 5 is formed so as to be arranged on the optical axis 8 of the laser light emitted from the laser diode 1, and the center 11 of the second lens 12 is transmitted through the second lens 12. A first lens in the vertical plane of the upper surface of the silicon substrate 2 including the optical axis 8 of the laser beam so that the laser beam enters the end face inclined with respect to the plane perpendicular to the central axis 9 of the optical fiber 6 at an angle α appropriately coupled thereto. The second V-shape is located at a position off the optical axis 8 of the laser light transmitted through It is formed with 14. In the laser diode module configured as described above, the optical coupling to the obliquely polished optical fiber 6 can be largely maintained without making the direction of the laser diode 1 oblique on the upper surface of the silicon substrate 2. The laser light reflected from the end face of the optical fiber 6 can be made to travel in a direction not returning to the laser diode 1.

Further, the center 4 of the first lens 3 is arranged at a position deviated from the optical axis 8 of the laser light in a vertical plane of the upper surface of the silicon substrate 2 including the optical axis 8 of the laser light emitted from the laser diode 1. Even when the V-shaped hole 5 is formed on the silicon substrate 2 as described above, the angle at which the laser light transmitted through the second lens 12 is optimally coupled to the end face inclined with respect to the plane perpendicular to the central axis 9 of the optical fiber 6. If the V-shaped hole 14 is formed so as to be incident at α, the same effect as described above can be obtained, and the reflection by the first lens 3 can be advanced in a direction that does not return to the laser diode 1.

FIG. 4 shows a fourth embodiment of the present invention, in which the center 4 of the first lens 3 is located within the vertical plane of the upper surface of the silicon substrate 2 including the optical axis 8 of the laser light emitted from the laser diode 1. Even when the V-shaped hole 5 is formed on the silicon substrate 2 so as to be located at a position deviated from the optical axis 8 of the laser light, and the optical isolator 10 is disposed between the first lens 3 and the second lens 12, The same effect as in the third embodiment can be obtained, and the reflection by the first lens 3 is
The laser beam can be made to travel in a direction not returning to the laser diode 1 and the laser light returning from the inside of the optical fiber 6 to the laser diode 1, which causes unstable operation of the laser diode 1, can be attenuated.

[0016]

According to the above invention, even if there is a reflection from the end face of the optical fiber, the light is not returned to the laser diode, and the light can be obtained only by installing the lens or the optical fiber in the V-shaped hole or the V-shaped groove. Since a module can be configured, a laser diode module that is easy to assemble and has good light coupling efficiency can be obtained at low cost.

Further, by arranging the optical isolator between the lens and the optical fiber, it is easy to assemble without returning the reflected light on the optical isolator, the surface of the optical fiber or the return light from inside the optical fiber to the laser diode. A laser diode module with stable operation and high light coupling efficiency can be obtained at low cost.

Further, using two lenses, the center of the second lens is located within the vertical plane of the upper surface of the silicon substrate including the optical axis of the laser beam emitted from the laser diode, from the optical axis of the laser beam emitted from the laser diode. By arranging the second lens so as to deviate, even if there is reflection from the end face of the optical fiber, it does not return to the laser diode,
In addition, since an optical module can be configured only by installing a lens or an optical fiber in a V-shaped hole or V-shaped groove, a laser diode module that is easy to assemble and has high coupling efficiency can be obtained at low cost.

Also, using two lenses, the center of the first lens is located within the vertical plane of the upper surface of the silicon substrate including the optical axis of the laser beam emitted from the laser diode, from the optical axis of the laser beam emitted from the laser diode. By disposing the first lens so as to be off, the amount of reflected light that is reflected from the first lens and returns to the laser diode can be reduced,
The optical module can be configured without returning the reflected light from the end face of the second lens or the optical fiber to the laser diode, and simply by installing the lens or the optical fiber in the V-shaped hole or the V-shaped groove. A laser diode module with high coupling efficiency can be obtained at low cost.

Further, the center of the first lens deviates from the optical axis of the laser light emitted from the laser diode within a vertical plane of the upper surface of the substrate including the optical axis of the laser diode. With the configuration in which the optical isolator is disposed between the first lens and the laser diode, the amount of light reflected from the first lens and returning to the laser diode can be reduced. The optical module can be constructed without returning the laser beam to the laser diode and merely by installing a lens or an optical fiber in a V-shaped hole or a V-shaped groove. A laser diode module can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a top view and a sectional view of a laser diode module according to a first embodiment of the present invention.

FIG. 2 is a top view and a sectional view of a laser diode module according to a second embodiment of the present invention.

FIG. 3 is a top view and a sectional view of a laser diode module according to a third embodiment of the present invention.

FIG. 4 is a top view and a sectional view of a laser diode module according to a fourth embodiment of the present invention.

FIG. 5 is a top view and a sectional view showing a conventional laser diode module.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser diode, 2 silicon substrate, 3 first lens, 4 center of first lens, 5 first V-shaped hole, 6
Optical fiber, 7 V-shaped groove, 8 Optical axis of laser beam, 9 Central axis of optical fiber, 10 Optical isolator, 11 V-shaped hole, 1
2 Second lens, 13 Center of second lens, 14 Second V-shaped hole.

Claims (5)

[Claims] 1. A laser diode, comprising a V-shaped hole and a V-shaped groove, a substrate on which the laser diode is mounted, a lens positioned in the V-shaped hole, and a lens positioned in the V-shaped groove. An optical fiber for coupling the laser light condensed by the laser light, wherein the center of the lens is a laser light emitted from the laser diode within a vertical plane of a substrate upper surface including an optical axis of the laser light. A laser diode module, wherein the V-shaped hole is formed at a position off the axis. 2. The laser diode module according to claim 1, wherein an optical isolator is provided between the lens and the optical fiber. 3. A substrate having a laser diode, first and second V-shaped holes and a V-shaped groove, on which the laser diode is mounted, and a first lens located in the first V-shaped hole. And a second lens positioned in the second V-shaped hole and condensing the laser light transmitted through the first lens; and a second lens positioned in the V-shaped groove and condensed by the second lens A first V-shaped hole formed so that a center of the first lens is on an optical axis of laser light emitted from the laser diode. The second lens is positioned such that the center of the second lens is located off the optical axis of the laser light transmitted through the first lens in the vertical plane of the upper surface of the substrate including the optical axis of the laser light. Laser diode module characterized by forming a V-shaped hole Jules. 4. A substrate having a laser diode, first and second V-shaped holes and a V-shaped groove, on which the laser diode is mounted, and a first lens located in the first V-shaped hole. A second lens positioned in the second V-shaped hole for condensing the laser light transmitted through the first lens, and a V-shaped groove for coupling the laser light condensed by the second lens The first V-shaped hole so that the center of the first lens is off the optical axis of the laser light emitted from the laser diode. The center of the second lens is formed at a position deviated from the optical axis of the laser light that is not parallel to the upper surface of the substrate that has passed through the first lens in a vertical plane of the upper surface of the substrate including the optical axis of the laser light. The second
A laser diode module, wherein the V-shaped hole is formed. 5. An optical isolator is provided between said first lens and said second lens.
A laser diode module as described.