JPH0636599Y2 - Semiconductor laser wavelength stabilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a wavelength stabilizer for a semiconductor laser suitable for use as a light source for various measurements and high-resolution spectroscopy. The present invention relates to a wavelength stabilizer.

<Prior Art> FIG. 2 is a diagram illustrating the structure of a wavelength stabilizer for a semiconductor laser that has been used conventionally. In the figure, light emitted from a semiconductor laser 1 is collimated by a collimator lens 2 and passes through a first isolator 3a and a second isolator 3b to reach a first beam splitter (for example, a half mirror ... hereinafter referred to as a half mirror) 4a. The light transmitted through the half mirror 4a becomes output light. On the other hand, the light reflected by the half mirror 4a reaches the second half mirror through the mirror 5, and the reflected light is converted into an electric signal by the first light receiving element 6a, and its output is input to the arithmetic unit 8. A predetermined wavelength of the transmitted light is selected by the etalon 7, and the light of the selected wavelength is the second wavelength.
Is converted into an electric signal by the light receiving element 6b and is input to the arithmetic unit 8. The arithmetic unit 8 performs a predetermined arithmetic operation based on the outputs of the first and second light receiving elements to control the current injected into the laser and contributes to the stabilization of the output of the laser light.

Here, two optical isolators are used for the following reason.

This device uses an etalon as a frequency selection means, but the reflectance of the etalon is close to 90%, and the return light is very large (when the return light enters the laser, the power and wavelength of the laser emission light become unstable. Become).

An isolation ratio of about 60 dB is required to eliminate the wavelength instability caused by the returning light, but there is no isolator that satisfies this condition.

Although not shown in the figure, the laser and the etalon are placed in a constant temperature bath and temperature controlled.

<Problems to be Solved by the Invention> According to the above-mentioned conventional device, two isolators are directly connected between the laser and the first half mirror as the return light preventing means. Generally, the insertion loss of each isolator is 1 to 3 dB, and when two isolators are directly connected, the loss is 2 to 6 dB. Therefore, there is a problem that the power of the laser is reduced.

The present invention has been made in view of the above problems of the prior art,
It is an object of the present invention to realize a device whose output power is improved by devising the arrangement position of the isolator.

<Means for Solving the Problems> The structure of the present invention for solving the above problems is a first half mirror arranged on the optical axis of a semiconductor laser and one of the first half mirrors branched by the first half mirror. A second half mirror for splitting the light, a first light receiving element for receiving one light split by the second half mirror, and a second light receiving element for receiving the other light via an etalon, In a wavelength stabilization device for a semiconductor laser, which comprises an arithmetic device for controlling an injection current to the laser based on an electric signal from these light receiving elements, in a return light of the etalon between the semiconductor laser and a first beam splitter. And a first isolator for blocking return light from the first beam splitter, a return light of the etalon and the second beam splitter between the first beam splitter and the etalon. By arranging a second isolator that blocks the return light from the first and second isolators, and insert the second isolator for the output light. It is characterized by eliminating insertion loss due to.

<Embodiment> FIG. 1 is a structural explanatory view showing an embodiment of the present invention. In the figure, the same elements as those in FIG. 2 are designated by the same reference numerals and the duplicated description is omitted, but in the present invention, only the arrangement position of the second isolator is different. That is, the second isolator is arranged between the first half mirror and the etalon.

According to the above configuration, the output of the laser 1 is the first isolator
Since it is output light after passing through 3a and the first half mirror 4a, it is not affected by the insertion loss of the second isolator 3b or the return light (about 4%) from the first half mirror 4a. And, for the return light of the etalon 7, the first and second
The two isolators 3a and 3b are used.

Although the second isolator is arranged between the first and second half mirrors in the figure, the second isolator may be arranged between the second half mirror and the etalon.

<Effect of Device> According to the present invention, as specifically described with reference to the embodiments, the light emitted from the laser only passes through the first isolator, so that the insertion loss of the isolator is halved compared to the conventional example. You can do it. As a result, it is possible to realize a wavelength stabilization device for a semiconductor laser having a large output power.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1 ... Semiconductor laser, 3a ... First isolator, 3b ...
... second isolator, 4a ... first beam splitter (half mirror), 4b ... second beam splitter (half mirror), 6a ... first light receiving element, 6b ... second light receiving element, 7 ... etalon, 8 ... arithmetic unit.

Claims (1)

[Scope of utility model registration request] 1. A first beam splitter arranged on the optical axis of a semiconductor laser, and a second beam splitter for splitting one light beam split by the first beam splitter,
A first light receiving element that receives one of the light beams split by the second beam splitter, a second light receiving element that receives the other light beam via an etalon, and the above based on electrical signals from these light receiving elements, In a wavelength stabilization device for a semiconductor laser, which comprises an arithmetic device for controlling an injection current to the laser, a return light of the etalon and a return light from the first beam splitter are provided between the semiconductor laser and a first beam splitter. And a second isolator for blocking return light of the etalon and return light from the second beam splitter between the first beam splitter and the etalon. Insertion by blocking the return light to the laser by the first and second isolators and inserting the second isolator into the output light Wavelength stabilizing apparatus for a semiconductor laser, characterized in that to eliminate the loss.