JPH02299279A - Oscillation wavelength stabilized semiconductor laser device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention uses the wavelength of a resonant absorption line of an atomic or molecular gas as a reference, and uses laser light as a reference for use as a wavelength reference in optical communication and optical measurement. This invention relates to a semiconductor laser device whose oscillation wavelength is stabilized by synchronizing the oscillation wavelength with the oscillation wavelength.

[Conventional technology]

An example of a conventional wavelength-stabilized semiconductor laser device will be described with reference to FIG. As shown in FIG. 4, this laser device uses a lens 2 to convert the emitted light from a semiconductor laser 1 into parallel light, passes it through a gas-filled glass tube, that is, an absorption cell 3, and then converts the emitted light into a parallel light through a lens. 4 condenses the light, and photodetector 5 performs photoelectric conversion. Then, this electric signal is sent to a feedback circuit 6.
After the treatment, the oscillation wavelength of the semiconductor laser is stabilized by feeding it back to the semiconductor laser 1.

Note that in FIG. 4, T is the main emitted light of the semiconductor laser 1. In this prior art, the absorption cell 3 is 105
Those with a length of 1 to 1 m were commonly used.

[Invention tries to solve! [1lill] However, in such a conventional semiconductor laser device, when the absorption cell structure as described above is used, the lenses 2 and 4. gas cell 3
The optical path is disturbed by the minute positional change of the semiconductor laser 1.
There was a problem in that it was difficult to properly pass the emitted light through the cell and to receive the light. In addition, in order to solve this problem, if the semiconductor laser, lens, cell, lens, and photodetector are installed on a strong fixed plate, the device will become larger and heavier, causing problems in the device configuration. was there.

The present invention has been made to solve this problem, and it is an object of the present invention to provide a practical oscillation wavelength stabilized semiconductor laser device that is compact and has an excellent optical system stability.

[Means to solve the problem]

In order to achieve the above object, the present invention allows light from a semiconductor laser to pass through an atomic or molecular gas that absorbs only light of a specific wavelength, and then to a photoreceiver. A semiconductor laser device that stabilizes the oscillation wavelength of the semiconductor laser by feeding back a corresponding electric signal to the semiconductor laser via a feedback circuit,
The present invention is characterized in that at least the semiconductor laser and the light receiver are provided in an absorption cell in which the gas is sealed.

[For production]

Therefore, in the present invention, a semiconductor laser that emits light and a light receiver are placed in an absorption cell filled with an atomic or molecular gas (hereinafter abbreviated as light-absorbing gas) that absorbs only light of a specific wavelength. By integrating the devices, it is possible to increase the light absorption intensity as much as possible and to suppress fluctuations in stability due to external disturbances.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a basic configuration diagram of the oscillation wavelength stabilized semiconductor laser device of the present invention, in which 11 is an absorption cell filled with a light-absorbing gas;
12 is a semiconductor 1/- laser, 13 is a light receiver, and 14 is a feedback circuit for stabilizing the oscillation wavelength. That is, the semiconductor laser device according to the present invention includes an absorption cell 11 filled with a light-absorbing gas.
A semiconductor laser 12 and a light receiver 13 are put in and integrally arranged inside, and light at a specific frequency is generated when the emitted light 16 from the semiconductor laser 12 is transmitted through the light-absorbing gas in the absorption cell 11. Using absorption, the transmitted light is photoelectrically converted by the photodetector 13, and then this electric signal is sent to the feedback circuit 14.
By processing it with and returning it to the semiconductor laser 12,
It is configured to stabilize the oscillation wavelength of the semiconductor laser.

FIG. 2 is a schematic diagram for explaining an embodiment of a semiconductor laser device for stabilizing the oscillation wavelength according to the present invention.
FIG. 2(a) is a three-dimensional internal structure diagram, and FIG. 2(b) is a sectional view thereof. In FIG. 2, 21 is the same semiconductor laser as in FIG. 1, 22 is the same light receiver as in FIG. 1, 23 is a hemispherical lens for focusing the laser beam on the light receiver 22, and 24 is the semiconductor laser 21 and a Peltier element for controlling the temperature of the light-absorbing gas in the device, and the detection signal of this Peltier element 24 is sent to a temperature control device (not shown) via a signal line to keep the temperature constant. It is designed to be controlled. Further, 25 is an optical fiber for emitting stabilized light, and 26 and 27 are stands for fixing the semiconductor laser 21 and the optical fiber 25, respectively.
These components are sealed together with a light-absorbing gas and then placed in a box 28 as an absorption cell made of glass, metal, or the like.

Next, the operation of the nine-oscillation wavelength-stabilized semiconductor laser device using the optical wavelength reference absorption cell of this embodiment will be explained with reference to FIG.

First, the emitted light 16 emitted from the semiconductor laser 21 passes through a light-absorbing gas filling the inside of the device, and light absorption occurs at a certain specific frequency. At this time, the intensity of light transmitted through the light-absorbing gas exhibits characteristics as shown in FIG. Furthermore, the oscillation frequency of the laser beam is synchronized with the absorption peak. Then, the transmitted light is collected by a hemispherical lens 23 and transmitted to a light receiver 22.
When photoelectrically converted by the photodetector 22, the photoelectrically converted signal 1
After T is sent to the oscillation wavelength stabilization feedback circuit 14 (see FIG. 1) and processed, this control signal 18 is used to adjust the current injected into the semiconductor laser 21 and adjust the oscillation wavelength of the semiconductor laser 21. is synchronized to the absorption line peak of the anti-aircraft body in the absorption cell and stabilized at this wavelength. This stable light is then obtained as the output of the optical fiber 25.

For example, in the device configuration of FIG. 2, the semiconductor laser 21
InGaAsP oscillates at a wavelength of 1.5300 μm as
In addition, the distance between the semiconductor laser 21 and the hemispherical lens 23 is defined as 1, and acetylene is used as the absorbing gas. If Torr is included, 1
．． The semiconductor laser 21 was wavelength-synchronized to the absorption line of 5315 μm (full width at half maximum 800 MHz, absorption intensity 50%) using gold. As a result, using this configuration system, the fluctuation of the central oscillation wavelength of the semiconductor laser can be controlled by
We were able to suppress the optical frequency to below MHz.

Note that, in addition to acetylene, ammonia gas, methane gas, carbon dioxide, or the like may be used as the light-absorbing gas to stabilize the oscillation wavelength using the same operating principle as described above.

Although the present invention has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above-mentioned Examples and can be modified in various ways without departing from the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, a semiconductor laser that emits light and a light receiver are placed in an absorption cell filled with a light-absorbing gas to integrate the device, thereby increasing the light absorption intensity as much as possible and reducing disturbance. Since fluctuations in stability caused by this can be suppressed, the oscillation wavelength of the semiconductor laser can be synchronized with a predetermined wavelength with extremely high precision and stabilized.

! ! 6. The oscillation wavelength stabilized semiconductor laser device of the present invention includes:
Since the optical system has excellent stability and can be miniaturized, it has the advantage that it can be used as a wavelength standard light source in coherent optical communication or as a light source in optical measurement.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the oscillation wavelength stabilized semiconductor laser device of the present invention, FIG. 2 is an internal structure diagram of an embodiment of the oscillation wavelength stabilized semiconductor laser device of the present invention, and FIG. 3 is a diagram of the above embodiment. FIG. 4 is a diagram showing the intensity of light versus optical frequency after passing through a light-absorbing gas to explain the operation. FIG. 4 is a block diagram showing the structure of a lost-wavelength stabilized semiconductor laser device using a conventional light-absorbing cell. . 11・e・Absorption cell, 12.21φ・・Semiconductor laser, 13,22・・・Photodetector, 14・・φ・Feedback circuit for stabilizing the oscillation wavelength, 23・・Fist hemispherical lens, 25・・・
-・Optical fiber, 26.27... stand, 28...
box. Patent Applicant: Nippon Telegraph and Telephone Corporation Agent: Masaki Yamakawa, Page 1, Figure 2 (CI) (b) 3rd = Koyanhakyo, 4th Engineering

Claims (1)

[Claims] The light emitted by the semiconductor laser passes through an atomic or molecular gas that absorbs only light of a specific wavelength, and then reaches a photoreceiver, and an electrical signal corresponding to the amount of light detected by the photoreceiver is sent to the above via a feedback circuit. In a semiconductor laser device that stabilizes the oscillation wavelength of the semiconductor laser by feeding back to the semiconductor laser, an absorption cell in which the gas is sealed includes:
An oscillation wavelength stabilized semiconductor laser device comprising at least the above semiconductor laser and a light receiver.