JPS61240220A - Optical beam shaping method for semiconductor laser - Google Patents

Abstract

PURPOSE:To simplify an axial alignment of an optical beam and a photodetector, and its fine adjustment by making an elliptical optical beam incident and transmit on and through two pieces of triangular pyramid-shaped prisms which is placed so that the position can be adjusted freely and have specified the vertical angle, shaping it to a true circular optical beam, and emitting it in parallel to the axial direction of an emitted optical beam from a semiconductor laser. CONSTITUTION:An elliptical optical beam collimated an emitted beam from a semiconductor laser 1 is made incident and transmit on and through two pieces of triangular pyramid-shaped prisms 3, 4 of a vertical angle alpha, which is placed so that the position can be adjusted freely. By adjusting the placed position of two pieces of prisms 3, 4, a transmitting optical beam is shaped to a true circle, and also emitted in parallel to the axial direction of the emitted optical beam from the semiconductor laser 1. In this way, an axial alignment of the optical beam which is shaped to a true circle and the photodetector, and its fine adjustment are executed very easily, also no making loss is generated, and also this method can be applied to the semiconductor laser having various broadening angles.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method of shaping a light beam of a semiconductor laser using a prism.

(Prior art) Conventionally, when a light beam is input from a semiconductor laser to a light receiving element, a collimator lens such as a ball lens or a cylindrical lens is placed just before the semiconductor laser to filimate the light beam emitted from the semiconductor laser. I was putting it into the photodetector, but
Since the collimated light beam has an inertial circular shape, a loss occurs in inputting the light beam to the light receiving element. In order to eliminate this input loss, a method has been proposed in which a collimated circular light beam is transmitted through a single prism and shaped into a circular shape, but the light beam emitted from the semiconductor laser is Since the spread angles are different, it is necessary to design and prepare a wide variety of prisms according to the spread angles. Also, when the light beam is shaped into a circle using - prisms, as shown in Figure 2, Semiconductor laser 10
As shown in the figure, there is an inclination between the axial direction of the emitted light beam and the axial direction of the light beam after passing through the prism 11 and shaping it into a circular shape. There were problems such as extremely difficult adjustment.

(Structure of the present invention) The method of the present invention has been made in view of the above points, and the method is to collimate the light beam emitted from the semiconductor laser, and then collimate the light beam into two circular light beams with an apex angle α arranged so that the position can be freely adjusted. It is characterized in that the light beam enters and passes through a triangular pyramidal prism, is shaped into a perfectly circular light beam, and is emitted in parallel to the axial direction of the light beam emitted from the semiconductor laser.

(Example of the present invention) Hereinafter, an example of the method of the present invention will be explained with reference to the drawings.
In Fig. 1, 1 is a semiconductor laser, 2 is a collimator lens consisting of a spherical lens, a cylindrical lens, etc. set immediately in front of the semiconductor laser, 3 is a triangular pyramidal prism with an apex angle α, and the number is the triangular pyramidal prism mentioned above. 3 and a triangular pyramidal prism with an apex angle α arranged symmetrically, both prisms have refractive index n = sin α = aid β, , , ,
(1) The inclination of the prism is the angle r=β−α, , ,
, (2) Adjust the position so as to satisfy the above beam width so as to satisfy the relationship between the minor axis diameter d' and the major axis diameter d of the elliptical beam, and emit light from a semiconductor laser with various spread angles. After collimating the beam with the collimator lens 2, the circular light beam is shaped into a perfect circle d° and is emitted in parallel to the axial direction of the light beam emitted from the semiconductor laser.

(Effects of the present invention) The method of the present invention is as described above, and after collimating the light beam emitted from the semiconductor laser 1, the inertial circular light beam is
The light beam enters and passes through two triangular pyramid-shaped prisms 3 and 3 whose apex angles are arranged so that their positions can be adjusted freely, and the transmitted light beam is shaped into a perfect circle by adjusting the arrangement positions of the two prisms 3 and 3. At the same time, since the light beam is emitted parallel to the axial direction of the light beam emitted from the semiconductor laser 1, alignment and fine adjustment between the perfectly circularly shaped light beam and the light receiving element can be carried out extremely easily, and moreover, no input loss occurs. Moreover, it has the excellent advantage of being suitable for semiconductor lasers having various divergence angles.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a conventional light beam shaping method.

Claims (1)

[Claims] After collimating the emitted light beam from the semiconductor laser, the circular light beam enters and passes through two triangular pyramidal prisms with an apex angle of α arranged so that the position can be adjusted freely, and is shaped into a perfect circular light beam. A method for shaping a light beam of a semiconductor laser, the method comprising emitting a light beam parallel to the axial direction of the light beam emitted from the semiconductor laser.