JP2000241659A - Method and device for combining light radiated from multi-mode laser diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase energy density per unit area, by collecting and shaping light radiated from a multi-mode semiconductor laser with a cylindrical lens, reflecting it with a total reflection mirror or a prism, making a dense arrangement substantially in parallel, and collecting and combining the outputted light. SOLUTION: A multi-mode semiconductor laser 2 is loaded on a heat sink 1, and is mounted to a caing with a heat radiation effect. A fast direction of laser light emitted from an emitter is first collected and shaped by a placed cylindrical lens 3, and next, its slow axis direction is collected and shaped by a cylindrical lens 4 whose emitted side is flat and opposite side is circular. The beams are reflected orthogonally by a total reflection mirror or a prism 5. In this case, the position of the mirror or the prism 5 is determined so that the reflected light is substantially parallel. A beam shape 9 on a glass surface at a glass window of the casing comes into a dense arrangement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coupling the output of a multimode semiconductor laser. More particularly, the present invention relates to a laser output coupling method capable of enhancing the output of a low-power laser device.

[0002]

2. Description of the Related Art In order to satisfy the demand for higher output of laser light, higher output of various laser light sources has been promoted. Among them, a semiconductor laser has attracted attention. There are mainly the following two methods for coupling the output of laser light known as a method for obtaining a high output so far.

"Polarization Coupling Method" As shown in FIG. 1, in this method, a pair of linearly polarized laser beams (101) and (102) whose light polarization planes are orthogonal to each other are combined with a polarization coupler ( 103).

According to this method, a set of laser beams (10
1) Although (102) is combined, the obtained laser light has a random phase difference and changes with time, so the combined light is also generally elliptically polarized light. In this method, two or more sets of laser light are combined. Can not. Further, in this light collecting device, it is extremely difficult and expensive to manufacture and assemble optical components.
"Fiber coupling method" On the other hand, a laser light coupling method using a fiber is also known. In this method, as shown in FIG. 2, laser light is incident on an optical fiber (104) having a diameter of, for example, about 100 microns, and this optical fiber (1) is used.
04) are combined to combine the outputs.

[0005] Although this method has the feature that the outputs of a large number of laser beams can be combined, the shape of the final output from the fiber is plural. In addition, the energy density per unit area cannot be increased, and the feature that many laser light outputs can be combined cannot be utilized.

[0006]

SUMMARY OF THE INVENTION The light emitted from a large number of low-power multimode semiconductor lasers is combined to increase the energy density per unit area, which is difficult with the conventional method, and the coupling device is an optical device. Significantly simplifying and reducing costs.

[0007]

The light emitted from each low-power multimode semiconductor laser is condensed and shaped by a cylindrical lens, reflected by a total reflection mirror or a prism, and the beams are made as dense and nearly as possible. The outputs are collected in parallel and combined. The light thus combined forms a substantially parallel beam and is condensed on a multimode optical fiber by disposing a condenser lens. For this reason,
The energy density per unit area also increases.

[0008]

Embodiment 1 A multi-mode semiconductor laser (2) having an emission size of 2 watts with an emitter size of 1 μm × 100 μm, a FWHM of 47 ° in a fast axis direction and a FWHM of 12 ° in a slow axis direction is used as a heat sink (1). And attach it to the housing (6) having a heat radiation effect. First, a laser beam emitted from the emitter is condensed and shaped by arranging a cylindrical lens (3) in the first axis direction, and then a flat-cylindrical lens (4) in which the slow axis direction is flat on the emitter side and the opposite side is cylindrical. ) And focus and shape. For example, the cylindrical lens (3) has a diameter of 0.5 mm and a focal length of 0.2 m
m, flat-cylindrical lens (4) has a lens diameter of 2 mm
-A focal length of 8 mm is desirable. The beam is reflected at right angles (8) by a total reflection mirror or prism (5). A component having the same configuration as 1 to 5 is 4 in this embodiment.
The pieces are arranged in a line in the direction of the slow axis. 5 mirrors or
The position of the prism is arranged such that the reflected light is substantially parallel. This housing (6) is made of quartz or sapphire glass (7) and is manufactured in a highly airtight state. The beam shape (9) on the glass surface in the glass window is densely arranged. The shape of each beam is 0.5mmx
2.0 mm, and the densely arranged and combined beam is 2.0 mm × 2.0 mm. A condensing lens (11) is arranged on the optical axis of this beam, and a multimode optical fiber (13) is arranged so as to be located at the focal point and condensed. The housing (14) is a connector (12) for accurately fixing the positions of the condenser lens (11) and the multimode optical fiber.
Has been arranged. The condenser lens (11) has a focal length of 4.5.
It is coupled to a multimode optical fiber having a core diameter of 60 microns and a NA of about 0.22 mm. A laser beam of 5 to 6 watts is obtained from the emission section of the multimode optical fiber.

[0009]

According to the present invention, the light emitted from the low-power multimode semiconductor laser is arranged in a substantially parallel beam state and at a high density, for example, so that the beams almost overlap each other. can do. As a result, for example, 5 to 6 watts or 6 to 6
With a diameter of 00 microns, a laser beam of about 90 watts can be collected. Such high-quality laser light can be expected to have great applications both in the medical field and for exciting single crystal lasers.

[Brief description of the drawings]

FIG. 1 shows a conventional polarization coupling method.

FIG. 2 shows a conventional fiber coupling method.

FIG. 3 is a first embodiment.

[Explanation of symbols]

 Reference Signs List 1, heat sink 2, multi-mode semiconductor laser 3, fast-axis cylindrical lens 4, slow-axis cylindrical lens 5, total reflection mirror (or prism) 6, housing 7, sapphire glass 8, laser beam after condensing, shaping and reflection 9, beam shape on sapphire glass surface 11, condenser lens 12, connector 13, multimode optical fiber 14, housing 101, laser light 102, laser light 103, polarization coupler 104, optical fiber

Claims (3)

[Claims] 1. An apparatus for combining light emitted from a plurality of multimode semiconductor lasers, wherein the light is separately focused and shaped in the first axis direction and the slow axis direction of a light emitting region of each multimode semiconductor laser. A device that reflects and combines the beams so that they are closely parallel and dense so that they do not overlap with each other by placing a total reflection mirror. 2. The coupling device according to claim 1, further comprising a condensing lens that collectively couples the beams on the optical axis of the beams that are substantially parallel and dense so as not to overlap, and condenses the light to a multimode optical fiber. apparatus. 3. A condensing device according to claim 1, wherein a condensing lens for collectively condensing each beam is arranged on an optical axis of the beams which are substantially parallel and dense so as not to overlap, and are combined on a spot. .