JPS5871687A - Semiconductor laser stabilized in oscillation wavelength - Google Patents

Abstract

PURPOSE:To enable to oscillate in single wavelength a semiconductor laser by employing a multimode oscillator, selecting the light of the specific wavelength from the emitted lights via a diffraction grating and feeding it back to the laser. CONSTITUTION:The luminous flux emitted from one end surface 4 of a semiconductor laser 1 is reflected and diffracted at a holographic diffraction grating 21, the primarily diffracted light 8 becomes parallel beam, is reflected on a reflecting mirror 22, is again reflected on the holographic diffraction grating 21, is focused on the laser 1, and is fed back. When the laser 1 is oscillated in multimode, the light diffracted via the grating 21 is incident at the different angles according to the wavelengths to the mirror 22. Accordingly, the mirror 22 is regulated so that the light of the desired wavelength is incident to vertical direction. The elements such as the laser element, holographic diffracting grating, reflecting mirror are determined at the relative positions in one package, thereby obtaining the semiconductor laser which is small sized, and can be extremely readily handled provided with stable oscillation wavelength.

Description

[Detailed Description of the Invention] This D invention uses a semiconductor V-za device in which the oscillation rIL length is stabilized, in particular a holographic diffraction grating.
Semiconductor laser devices that are optically stabilized and can be treated as υWIR ＠ Semiconductor lasers are finding good use as small D-coherent light sources. Conventionally, when trying to obtain a ◆-mode oscillation element as a semiconductor laser, the oscillation wavelength changes due to changes in the temperature of the laser element. The device was placed on a Peltier effect element, and while detecting the laser element Daf, the semiconductor laser element was cooled by the Peltier effect element so that 77) lit remained constant, thereby stabilizing the oscillation wavelength. , temperature control KIυ accuracy has a limit α1℃M!
The degree υ variation is unavoidable, and this causes a wavelength variation of IA duck 1. In order to perform high-precision temperature control, a large Peltier effect element and a high IIA temperature sensing element are required, making the device expensive.90In contrast, semiconductor laser elements By using a multi-mode oscillation element as a multi-mode oscillation element, selecting a specific wavelength υ from the output light using a diffraction grating, and feeding this back to the semiconductor laser, it is possible to oscillate at a single wavelength, and this oscillation wavelength is It is known that the invention is stable against changes in temperature, etc. The present invention uses this material to create a compact and stabilized illuminant. The purpose of this invention is to obtain a semiconductor laser device in which the oscillation wavelength υ is stabilized and the oscillation wavelength υ is integrated.

Figures 1 to 3 are explanatory diagrams of the principle of this invention.
, @1 Figure shows the emitted light intensity of the @rO multimode oscillation semiconductor laser versus wavelength when the oscillation wavelength is not stabilized.
The emitted light beam 5 from the amorphous surface 4 is collimated by the collimator lens 11 and made incident on the retro-arranged diffraction grating 12, and 2) the first-order diffracted light is again focused by the lens IIK onto the semiconductor laser ID@injection layer 6. Let light enter. semiconductor laser l
As shown in FIG. 1, O3λ-2. λ−1%λ. ,
In other words, the emitted light 5 is split into multiple modes by diffracted photons 12 at λ1, λ2, and λ, and is split into rays on the semiconductor laser f12) ili surface 4 as shown in FIG. The collimator lens 11 displaces the ◎ ◎ there, and the υ point υ and the arbitrary υ on the back, for example λ. DtI
The inclination of the diffraction grating 12 is set to 1ilIiJ so that the L pseudo υ junction point is imaged onto the active injection layer 6 of the semiconductor laser 1υ! I am
The semiconductor laser 1 has a wavelength λ. The emitted light component υ is fed back and the wavelength λ. The D-mode oscillation starts to occur at λ, and the D-mode oscillation shows good stability even when changing to a temperature of λ. butterfly, diffraction grating 122) change the tilt,
Wavelength λ, 2)! i! ! The image point is the active layer 6 of the semiconductor laser l.
All you have to do is make it incident on .

By the way, in the case of a semiconductor laser, the oscillating light 3 is also emitted from the 11υ end face 2 opposite to the end face 4 to which a specific wavelength t is fed back. By incorporating a semiconductor laser device into one body with a laser element, oscillation [1υ
In order to stabilize the oscillation wavelength υ, which can be used as a stable laser device, a bright feedback optical system is required, and an optical system using a collimator lens or diffraction grating requires heavy equipment and low cost. There is a limit to price reduction.◎Holographic diffraction gratings can be advantageously used for such purposes.

Figure 4 shows the 70 optical system arrangement @semiconductor laser 1'ri1
The light flux emitted from the 0IlIII surface 4 is reflected and diffracted by the holographic diffraction grating 21, and the first-order diffraction light 8 becomes parallel light, reflected by the reflecting mirror 22, and reflected again by the holographic diffraction grating 21, and then reflected onto the semiconductor laser l. Feedback is provided in a concise manner. If the semiconductor laser 1 oscillates in multiple modes as shown in the first figure, the light diffracted by the holographic diffraction grating 21 will be incident on the reflecting mirror 22 at different angles depending on the wavelength. 0 or 5 oscillation wavelengths, λ-1, λ-2, λ-1, λ, adjusted so that the wavelength light is perpendicularly incident. , λ1, λ2,
λ, ■For example, the wavelength λ.

If the reflecting mirror 22 is adjusted so that the D-light Of order diffracted light enters the reflecting mirror 22 directly, the wavelength λ. The D emitted light 0+ passes through the reflection@22 holographic diffraction grating 21, focuses on the upward trend of the semiconductor laser 1υ active injection layer 6, and is fed back. On the other hand, light of other υ wavelengths enters the reflecting mirror at different angles.

Since the light is reflected and returns to a position different from the position from which it was emitted, it is no longer focused on the active layer 6.

In this embodiment, the holographic diffraction grating performs the light focusing action, thereby eliminating the need for a collimator lens.A method for manufacturing the holographic diffraction grating used herein is shown in FIG. Emitted light from a coherent light source 51 such as a laser is turned into parallel light by a collimator lens 52 and split by a beam splitter 54. One light beam is once focused by a converging lens 53 and then becomes a single diverging light to be sent to a hologram recording material. The zero power p light incident on the light source 50 is reflected by the reflecting mirror 55, and enters as a parallel light p, which interferes with the previous υ divergent light, and this υ interference pattern is recorded on the hologram recording material. As this recording material, a known hologram recording material such as a silver salt dry plate, dichromate gelatin, or photoresist is used. The light used to create holograms is
Semiconductor laser IE) oscillation & λ in the above example
. It may be different from ′&λ. It is desirable for D to be dispersed, and the focal point 0 of the light beam in the crane 5- and the hologram recording material 50θ position coincide with the D light beam output position from the semiconductor laser ID end face and the holographic diffraction grating 217) position, respectively, in FIG. It's a shame.

Figure l16 shows an example in which the optical system arrangement shown in Figure 4 is integrated as a semiconductor laser package.
The holographic quick diffraction grating 21 is fixed on the same mount 60 at a predetermined O angle. After the mount 60 is fixed in the package 61, the reflector 22 is adjusted to the position where the holographic quick diffraction grating 210 will be received next time, so that the semiconductor laser oscillates in the fist mode at a predetermined om*. package 6
Fixed to 1. In the figure, 62 is a D window for emitting a light beam stabilized at a predetermined wavelength from the semiconductor laser device. In addition, for the lifting platform where you want to monitor the semiconductor laser D light output,
The reflecting mirror 22 may be a semi-transmissive mirror having a light receiver on its back surface.

This invention has the above-mentioned configuration and has the following remarkable effects.0 ■ Using a multi-mode oscillation semiconductor laser element, the oscillation light is fed back by using the surface opposite to the emission surface from which the emitted light is normally taken out. However, since stabilization is performed, the feedback optical system has no effect on normal use, and can utilize a laser beam that is stable against temperature changes and the like.

(2) By using a holographic diffraction grating as a feedback optical system, a collimator lens is not required, and the optical system can be constructed extremely easily and compactly.

■ Living body - A single oscillation system that is smaller and extremely easy to handle than by fixing each element such as the element, holographic diffraction grating, and reflecting mirror in the relative position in the D package. It is possible to obtain a semiconductor laser watt whose wavelength υ is stable.

■ The oscillation wavelength can be freely selected within a certain range by simply changing the inclination of the reflecting mirror that receives the first-order diffracted light from the holographic diffraction grating.

[Brief explanation of the drawing]

Figure 1 is an oscillation spectrum diagram of a conductor laser during multi-mode oscillation, Figures 2 and 3 are explanatory diagrams of FIAll of this D invention, C4
The figure is a layout diagram of an optical system according to an embodiment of the υ invention, Figure 15 is a layout diagram of an optical system for creating a holographic diffraction grating, and Figure 6 shows an example of the θ living body laser device 2) of this invention. Cross-sectional view C1: #-conductor laser element 2.4: Laser emission end face 6: Active layer 12: Diffraction device m 21: Holographic diffraction grating 22: Reflector 50; Holographic recording material 54: Beam splitter 60; Mount
61: Nokutsu Cage 62: Mado Tokukende-jin Legal Company Ricoh

Claims (1)

[Claims] Multi-mode oscillation semiconductor laser device 2) A laser beam is extracted from one end face, and the θ emitted light from the other end face is separated by a spectrometer, and the desired wavelength component O is extracted from the emitted light 11! Semiconductor laser device with stabilized oscillation wavelength that returns to the plane