JPS6383707A - Mutliterminal laser diode module - Google Patents

Abstract

PURPOSE:To insert light into a coming-out fiber arrays from a laser diode by abutting the light emitting surface of the laser diode on the one end surface of a slab-like lens with a large aperture angle and abutting the end surface of the fiber array on the end surface of a slab-like lens with a small aperture angle. CONSTITUTION:The light emitting surface of the laser diode 6 is abutted on the one ends of two unidirectional refraction factor distribution type slab-like lenses 4 and 5 whose end surfaces border. The end surface of the optical fiber array 7 in which plural optical fibers are arrayed is abutted on the other ends. In the lenses 4 and 5, their refraction factors slowly decrease according to expression I from the plane of a central optical axis to the periphery only in a direction (y) on the plane in parallel with both end surfaces. However, their refraction factors are uniform in a direction (x). The length of lenses 4 and 5 are 1/4 pitch determined by their constants g0. Thus the lens 4 with a large aperture angle efficiently converts a laser beam coming out of the laser diode at a maximum coming-out angle in the direction into a parallel beam. The lens 5 with a small aperture angle and a long pitch length condenses the parallel beam at a small aperture angle.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a multi-terminal sear diode module that evenly and efficiently distributes output light from one laser diode to one terminal of a plurality of optical fibers. It is.

[Background Art] In recent years, optical communication is reaching the point of practical use as the performance of optical fibers and laser diodes has improved. One of the optical beam control technologies used in such optical communication systems is the optical coupling technology between the output light of a laser diode or light emitting diode, which is a light source, and one terminal of an optical fiber.
This is an important technology indispensable for optical communications. In particular, the IS multi-terminal laser diode module is capable of extracting multiple pieces of homogeneous light from a single light source, and integrates the laser diode of the light source with multiple optical fibers on the output side. It is indispensable for the Ll-Cal Air Area Network System (LAN).

Conventionally, this type of multi-terminal laser diode [-Joule] used a gradient index slab lens whose refractive index IJi decreases in the direction approximately proportional to the square of the distance from the optical axis plane. What was there is known.

A slab-like lens has a refractive index distribution in a direction such as
The refractive index in the direction is n (y)2=n. ' (1-oo2y2) [However,
No is a refractive index on the optical axis plane, qo is a constant q, and the lens has a refractive index that does not change in the X direction J3 and two directions that are orthogonal to the Y horn direction. Therefore, the first
A laser diode 2 and a plurality of optical fibers are distributed on both end faces of a slab-like lens 1 with a diameter of 1/2 pitch (or a multiple of 1/2 pitch) with dimensions J shown in the figure and Figure 2. When the optical fiber array 3 is placed in contact with the laser diode, in the direction in which the slab-shaped lens has the refractive index molecule i, that is, in the X direction, the light beam emitted from the laser diode is focused on the end face of the slab-shaped lens. In the X direction, the side surface C of the slab-like lens repeats or goes straight to reach the optical fiber array 3, so that the output light of the laser diode can be uniformly distributed. Here, one bit refers to one cycle of light that meanders through the lens.

[Problems to be Solved by the Invention] In general, laser diodes emit laser light at different angles in the direction perpendicular to and parallel to the junction surface of the semiconductor, and it is common for the former to be larger than the right side. Are known. Therefore, when using a laser diode with a large maximum output angle, use a slab-shaped lens with a large aperture angle in the direction of the refractive index distribution, and bond the laser diode with this in the direction of the maximum output angle. However, since laser diode modules are generally used in the optical communications field, quartz fibers are often used in fiber arrays, and quartz fibers are often used in fiber arrays. Since the aperture angle of the fiber is as low as around 0.2, it is not possible to efficiently receive the laser light focused by the slab lens.

On the other hand, if the aperture angle of the slab lens is made smaller to match the quartz fiber, it will no longer be able to efficiently receive the output light from the laser diode.

The present invention solves the problems of the prior art as described in ``-'', and efficiently produces a beam 1f emitted from a laser diode.
- To provide a multi-terminal laser diode module capable of receiving light and inserting it into a low volume 1] angle fiber array.

[Means for Solving the Problems 1] In order to achieve the above object, the present invention reduces the refractive index in one direction approximately in proportion to the square of the distance from the optical axis plane, and the aperture angle is relatively large. Gi-h tropic gradient index slab lens A
J3 and a slab-shaped lens B with a relatively small aperture angle similar to the one described above, each having a length that is an odd multiple of approximately 1/4 pitch, and the direction of the refractive index distribution is The components are a pair of lenses that are in contact with each other at their end faces so that they overlap, a fiber array with multiple optical fibers arranged, and a laser diode, and the aperture angle in the direction of the refractive index distribution is equal to the maximum output angle of the laser diode. The redundant surface of the laser diode is brought into contact with one end face of a slab-shaped lens Δ with a relatively high aperture angle, and the aperture angle in the direction of the refractive index distribution is approximately equal to the aperture angle of the fiber array. There is also a multi-terminal laser diode module C in which the end face of a fiber loop is brought into contact with the end face of a shaped lens B.

[Operations and Uses] By employing the above-mentioned means, the present invention can efficiently insert and distribute output light from a laser diode having a high emission angle into a fiber array having a low aperture angle.

[Example] Embodiments of the invention shown in the drawings will be described below.

FIGS. 3 and 4 show an embodiment of the present invention, in which a laser diode 6 is mounted on one side of two unidirectional index gradient index slab lenses 4 and 5 whose end surfaces are in contact with each other. The light emitting surface of the optical fiber array 7 is brought into contact with the other end surface, and the end surface of an optical fiber array 7 formed by arranging a plurality of optical fibers is brought into contact with the other end surface. Slab lenses 4 and 5 have a refractive index of n (V )2=n 2 (1-go' y2)[n
is the refractive index on the optical axis plane, qo gradually decreases according to the constant 1, but the refractive index is uniform in the X direction, and the slab lenses 4 and 5 each have a 1/4 pitch determined by the constant q of The length of the slab lens 4 is as follows.
Among the emission angles of the laser diode 6 (generally, the emission angle is different in the direction perpendicular to the bonding surface and in the direction horizontal to the bonding surface, and the former emission angle is larger), a high aperture angle (approximately equal to the maximum emission angle) (refers to the aperture angle in the direction that has a refractive index distribution)
The laser diode 6 is a slab-shaped lens having a laser diode 6, and the two are joined together so that the direction of the maximum emission angle of the laser diode 6 matches the direction of the refractive index distribution (X direction) of the slab-shaped lens 4. Here, the slab-like lens with a high aperture angle can be manufactured by a method as disclosed in Japanese Patent Application No. 146913/1989, previously filed by the applicant of the present invention.

- On the other hand, when using a fiber array in which a plurality of quartz fibers are arranged as the fiber array 7, for example, the slab-like lens 5 has an aperture angle of 0, which is the aperture angle of the quartz fibers.
, a low aperture angle slab-like lens having a refractive index distribution with an aperture angle approximately equal to 2, the direction of the refractive index distribution being in the same direction as the direction of the refractive index distribution of the high aperture angle slab-like lens 4. It is joined to the high volume corner slab lens 4 and also joined to the fiber array 7. Here, a slab-like lens with a low aperture angle can be easily manufactured by the method described in Japanese Patent Publication No. 5661/1983.

In the multi-terminal laser diode module configured in this manner, the laser beam in the X direction emitted from the laser diode at the maximum output angle is first efficiently converted into parallel light by the slab-shaped lens 4 with a large aperture angle, as shown in FIG. Further, the parallel light is condensed at a low aperture angle by the low aperture angle slab lens 5 with a long pitch length, and is efficiently inserted into a fiber having a low aperture angle.

Laser light in the X direction emitted at an exit angle much smaller than this is repeatedly reflected on the side surfaces of the slab lenses 4 and 5, or goes straight, although there is some loss due to the mismatch in the aperture angle. As a result, the fibers reach the fiber array 7 and are evenly distributed.

In this case, by coating both side surfaces in the X direction with reflective films, loss of light in the X direction can be prevented.

[Effects of the Invention] This invention, configured as described above, has an excellent effect in that the light emitted from the laser diode having a high emission angle can be efficiently and evenly distributed to each optical fiber. It is.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing how light travels in the X direction and the X direction in a conventional multi-terminal laser diode module, respectively. FIGS. 3 and 4 show an example of the configuration of the present invention and the X direction, respectively. FIG. 3 is an explanatory diagram showing how light travels in the X direction. 1; Slab lens, 2, 6: Laser diode,
3 and 7 are fiber arrays, 4 is a high volume corner slab lens, and 5 is a low volume corner slab lens.Applicant: Hoya Co., Ltd.

Claims (1)

[Claims] a unidirectional gradient index slab lens A whose diffraction index decreases in one direction in proportion to approximately the square of the distance from the optical axis plane, and which has a relatively large aperture angle with respect to the direction of the refractive index distribution;
A similar unidirectional refractive index distribution type slab-like lens, which has a relatively small aperture angle in the direction of the refractive index distribution, and lens B are each formed with a length that is an odd number multiple of approximately 1/4 pitch. , and so that the directions of the refractive index distribution match,
Consisting of a pair of lenses that abut each other at their end faces, a fiber array in which multiple optical fibers are arranged, and a laser diode, it has a high aperture angle slab shape in which the aperture angle in the direction of the refractive index distribution is equal to the maximum output angle of the laser diode. The light emitting surface of the laser diode is brought into contact with one end surface of lens A, and the end surface of the fiber array is brought into contact with the end surface of low aperture angle slab-like lens B, whose aperture angle in the direction of the refractive index distribution is approximately equal to the aperture angle of the fiber. An integrated multi-terminal laser diode module.