JPS6393181A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To prevent noises due to the interaction of returning beams and internal propagating beams by forming first and second resonator regions mutually connected on both end surfaces of a resonator so as to shape an annular optical guide and a waveguide region leading out laser beams to the outside of a laser. CONSTITUTION:Beams moving forward in the clockwise direction or the counterclockwise direction on an annular optical guide shaped by first and second resonator regions 12a, 12b are each amplified lndependently, but only beams propagated in the counterclockwise direction on the annular optical guide are propagated over a waveguide region 13 and extracted as a laser beam output. Even when returning beams advance in the waveguide region 13 from the outside, the returning beams are coupled only with beams proceeding in the clockwise direction and amplified in resonator regions 12. Accordingly, the returning beams have no effect on beams amplified in the counterclockwise direction related to the laser output and do not generate interaction, thus generating no noise due to interaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser, and particularly to a semiconductor laser that suppresses noise due to returned light.

[Conventional technology]

FIG. 2 is a diagram showing a resonator region formed on the active layer of a conventional semiconductor laser. In the figure, 21 is a semiconductor laser chip, 22 is a resonator region, and 23a+23b are resonator end faces.

Next, the operation will be explained. The light propagating along the resonator region 22 while being amplified is partially reflected by the resonator end face 23a, and partially transmitted, resulting in optical output. The reflected light propagates again through the resonator region 22, this time while being amplified in the opposite direction.

The light that has reached the resonator end face 23b on the opposite side is reflected and transmitted here in the same manner as at the resonator end face 23a, and the same operation is repeated.

[Problem that the invention seeks to solve]

In conventional semiconductor lasers, light is amplified while going back and forth in the cavity region, so when light returns randomly from outside the semiconductor laser chip, it interacts with the light propagating inside the laser cavity. There was a problem in that the noise may occur or not occur, resulting in a large amount of noise.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a semiconductor laser in which the lights do not interact and do not generate noise even if there is light returning to the semiconductor laser.

[Means for solving problems]

In the semiconductor laser according to the present invention, first and second waveguides are connected to each other at both end faces of a resonator so as to form a ring-shaped leading wavepath. a second resonator region; and a waveguide region connected to either of the first and second resonator regions and guiding laser light to the outside of the laser from a ring-shaped optical waveguide made up of both the resonator regions. It is prepared.

[Effect]

In this invention, the first... a second resonator region; a waveguide region that is connected to either of the second resonator regions and guides the laser light to the outside of the laser from the annular optical waveguide made of both the resonator regions; Only one of the circular and counterclockwise laser beams is derived as a laser beam, and the return light from the outside is input in the opposite direction to the direction in which the above laser beam is amplified, so it propagates inside the resonator together with the return light. No interaction with the existing light occurs, and noise due to this interaction is prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a diagram showing the structure on the active layer surface of a semiconductor laser according to an embodiment of the present invention. In the figure, 11 is a semiconductor laser chip, and 12a and 12b indicate that light traveling in one direction does not travel in the opposite direction due to reflection or the like. The first and second resonator regions form a circular optical waveguide, and 13 is a resonator region 12.
resonator region 12a, so as to extract only light in one direction out of the light in two directions amplified by a and 12b as a laser beam;
12b, a waveguide region formed by connecting to either one of the waveguide regions 1
4a and 14b are end faces of the resonator.

Next, the operation will be explained. In the semiconductor laser of this embodiment, the first. a second resonator region 12a,
Although the light traveling clockwise and counterclockwise on the annular optical waveguide formed by the annular optical waveguide 12b is amplified independently, it is the annular optical waveguide that propagates to the waveguide region 13 and is extracted as laser light output. It is only light that propagates counterclockwise along the wave path.

Now, even if the returned light enters the waveguide region 13 from the outside, the returned light travels clockwise in the resonator region 12 and is only coupled with the amplified light.

Therefore, this does not affect the counterclockwise amplified light related to the laser output, and no interaction occurs.
No noise is generated due to this interaction.

In addition, here, the above 1. Second resonator region 12a, 12
b shows that the light guided through the annular leading waveguide reaches the resonator end face 14.
It is provided at a predetermined angle from perpendicular to the end face so that it is totally reflected by a and 14b.

Further, in the above embodiment, a case has been described in which light that is amplified in a counterclockwise direction is extracted as a laser beam, but it goes without saying that the light that is extracted may be extracted in a clockwise direction.

〔Effect of the invention〕

As described above, according to the present invention, the first... a second resonator region; and a waveguide region connected to either of the first and second resonator regions and guiding laser light to the outside of the laser from a ring-shaped optical waveguide made up of both the resonator regions. The laser beam is amplified in the annular optical waveguide, and only one of the clockwise and counterclockwise laser beams is guided out as a laser beam, and the return light from the outside is incident in the opposite direction to that in which the laser beam is amplified. Since the structure is configured in such a way that noise caused by returning light can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a top view showing the structure on the active layer surface of a semiconductor laser according to an embodiment of the present invention, and FIG. 2 is a top view showing the structure on the active layer surface of a conventional semiconductor laser. 11 is a semiconductor laser chip, 12a and 12b are first . A second resonator region, 13 is a waveguide region, 14a and 14b are resonator end faces, 21 is a semiconductor laser chip, 22 is a resonator region, and 23a and 23b are resonator end faces.

Claims (1)

[Claims] (1) In an internal cavity type semiconductor laser, first and second cavity regions are connected to each other at both end faces to form an annular optical waveguide in the plane of the active layer; 1. A semiconductor laser comprising a waveguide region connected to either one of the second resonator regions and guiding laser light to the outside of the laser from an annular optical waveguide made up of both the resonator regions. .