JPH02303082A - Optical oscillator - Google Patents

Abstract

PURPOSE:To effectively oscillate intense laser light by forming an optical waveguide in a taper type, making the introduced light travel while reflecting the light by taper surfaces, and effectively Supplying the transferred light through an optical fiber to an optical oscillator part. CONSTITUTION:The optical waveguide 2 of an optical oscillator is formed in a taper type. Light introduced into the optical waveguide 2 from an optical fiber 4 via the wide sectional area 2A of the optical waveguide 2 travels toward the tip narrow 2B side of the optical waveguide 2, while being reflected by the taper surfaces. During this process, the light intersects the center line part several times. When light is introduced into the taper type optical waveguide 2 from the wide sectional area 2A side, the cross angle wherein the reflected light of the introduced light intersects the center axis O-O becomes sequentially large on the taper surface 2C of the optical waveguide 2, as compared with the incident light. As the light travels toward the tip part 2B, the number of intersecting times for the center line per unit distance increases, and the number of intersecting times for an optical oscillator part 1 arranged on the tip side of the optical waveguide 2 increases. Thereby the light introduced into the optical waveguide 2 is effectively utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation technique in an optical oscillator, and more particularly, in a laser oscillator.

A solar-pumped laser is a laser that uses sunlight as the excitation light, and uses solar energy coherently.

It can be directly converted into higher quality energy.

Today, laser light sources are indispensable in fields such as optical communications, nuclear fusion, semiconductor industry, and medicine.

Solar-pumped lasers open up a new field of solar energy utilization. This is especially useful in outer space, where much of the energy must be derived from sunlight. Regarding such solar pumped lasers, for example, Mr. Haruo Arashi has published Solar Energy Vo1.12. No, 1.
1986. Transmission of high-density solar energy using optical fibers - application to solar pumped lasers - has already been proposed.

The present applicant previously proposed that in the above-mentioned optical oscillator, light energy is effectively given to the scattering (excited) substance, thereby obtaining high-output light.

Fig. 2 is a principle diagram for explaining an example of an optical oscillator previously proposed by the present applicant. :YA
G crystal laser rod) or one containing gas or liquid inside, one end surface 1a of which is incomplete (9
5%) reflective surface (dielectric multilayer film), and the other surface 1b is normally formed as a completely (about 100%) reflective surface (dielectric multilayer film). 2 is a cylindrical light guide that covers the periphery of the columnar light oscillating part 1, and the refractive index of the light guide 2 is as shown in FIG.
As shown in b), the outer periphery is small and the size increases toward the center. Both end surfaces 2a and 2b of the light guide 2 are formed in the shape of a convex lens, and one end surface, for example,
A reflective film 3 is provided on the outside of the 2a side. Reference numeral 4 denotes an optical fiber through which light is transmitted, and it has a large number of optical fibers 4, and the end face (light emitting end) of each optical fiber 4 is adhered to the other end 2b of the light guide 2 with optical glue or the like.

Therefore, all of the light transmitted through each optical fiber 4 is introduced into the light guide 2 without being reflected by the end face 2b of the light guide 2. The light introduced into the light guide 2 is
Since the light guide 2 is formed so that the refractive index at the center is larger than the refractive index at the outer periphery, the light guide 2 is bent toward the center while propagating inside the light guide 2, and the final is introduced into the optical oscillation section 1. The light that has not been introduced into the optical oscillator section 1 is reflected by the reflective film 3 on the other end surface 2a side of the optical guide 2, and the reflected light is directed toward the center in the same manner as described above and is directed toward the optical oscillator section. 1. The light introduced into the light oscillation section 1 in this manner excites the excited substance within the light oscillation section 1, giving and receiving energy equal to the difference between the energy levels of the substance, as is well known. Then, light with a wavelength corresponding to the difference is emitted from the incompletely reflective surface 1a side.

As the applicant has already proposed variously, it is possible to introduce light of any desired wavelength into each of the above-mentioned optical fibers 4 by focusing artificial light or sunlight with a lens or the like. Light of a desired wavelength is introduced into each optical fiber 4 as described below.

FIG. 4 is an overall perspective view showing an example of a sunlight collecting device previously proposed by the present applicant, in which 21 is a cylindrical base portion;
2 is a transparent dome-shaped head, which constitutes a capsule 20 for a solar collector; in use,
A sunlight collecting device 10 is housed within the capsule as shown.

This solar light collection device 10 has the following functions for converging sunlight:
One, several or many lenses 11. A sunlight direction sensor 12 for detecting the direction of the sun; a support frame 13 that holds these together; A first rotation shaft 14 for rotating the support frame 13, a first motor 15 for rotating the first rotation shaft 14, a support arm 16 for supporting the lens 11 to the motor 15, and the first rotation shaft 14 for rotating the support frame 13. It has a second rotating shaft 17 disposed perpendicular to the first rotating shaft, a second motor (not shown) for rotating the second rotating shaft 17, and the like.

The direction of the sun is detected by the sunlight direction sensor 12, and the first and second motors are controlled based on the detection signal so that the lens 11 always faces the sun, and the sunlight focused by the lens 11 is controlled. The light is introduced into an optical fiber (optical fiber 4 shown in FIG. 2) whose light-receiving end is disposed at the focal position of the lens 11, and transmitted to the optical oscillator through the optical fiber.

FIG. 5 is a diagram for explaining an example of introducing light corresponding to the visible light component of sunlight into the optical fiber 4. In the figure, 11 is a lens system such as a Fresnel lens (shown in FIG. 4). (equivalent to lens 11).

4, the sunlight focused by the lens 11 is introduced,
An optical fiber is used to transmit sunlight. When the sunlight is focused by a lens system, the image of the sun becomes almost white light at the center, and the wavelength corresponding to the focal point at the periphery. contains a large amount of light components.

That is, when sunlight is focused by a lens system, the focal point position and the size of the solar image differ depending on the wavelength of the light. For example, for blue light with a short wavelength, a solar image of diameter Dt is placed at the position of Pi, and a sun image of diameter Dt is placed at the position of green light. The light system forms a sun image with a diameter D2 at the position P2, and the red system light forms a sun image with a diameter D2 at the position P3.

Therefore, in the case shown in the figure, if the light-receiving end face of the optical conductor cable is placed at the position of P, it is possible to collect sunlight that contains a lot of blue component light in the peripheral area, and if it is placed at position P2, sunlight that contains a lot of blue component light can be collected. It is possible to collect sunlight that contains a lot of red system light components in the periphery by placing it at the position P3. For example, when it is a blue color, it is 0, and when it is a green color, it is D2.
, if you set it to D3 for red light, you can reduce the usage of the light guide cable and collect sunlight containing a large amount of the desired light component most efficiently.As shown in the figure, the light guide cable By increasing the diameter of the light-receiving end face to Do, it is possible to collect light that includes all wavelength components, that is, visible light components.

As shown in FIGS. 4 and 5, the optical fiber 4 shown in FIG. Light containing a large amount or light containing a large amount of red component is introduced, and the light thus introduced into the optical fiber 4 is used as excitation light for the optical oscillator. Therefore, one aspect of the present invention is
It was primarily designed for use in outer space, such as in communication satellites.

In particular, it aims to effectively utilize sunlight in outer space, which is a valuable source of energy. In other words, in outer space, there is no difference between day and night, and sunlight is not blocked by clouds.

It is possible to use sunlight stably at all times, and it is most suitable for using the optical oscillator according to the present invention, and the optical oscillator is used to relay signals from the ground, or for communication satellites Sending information from spacecraft etc. to the ground,
Alternatively, it can be used as a laser light source for cutting during machining, etc., inside and outside the spacecraft.

The present invention has been made for the purpose of further improving the above-described optical oscillator and providing an optical oscillator that can oscillate more effective and more powerful light. .

Figure 1 is a block diagram of main parts for explaining one embodiment of the optical oscillator according to the present invention. The same reference numbers as in Figure 2 are given.

Therefore, in the present invention, the light guide 2 is formed in a tapered shape, and the light introduced into the light guide 2 from the wide cross-sectional area 2A side of the guide body 2 from the optical fiber 4 is transmitted through the tapered surface. It travels toward the tapered 2B side of the light guide 2 while being reflected by the light guide 2, and intersects the center line of the light guide 2 several times during that time. When light is introduced into the tapered light guide from the wide cross-sectional area 2A side as shown in the figure, the introduced light is reflected at the tapered surface 2C of the guide, but the reflected light is
Compared to the incident light, the angle θ at which it intersects the central axis O-O gradually increases, and as it approaches the tapered tip 2B of the taper, the number of times it intersects the central axis per unit distance increases. When the light guide section is disposed on the tapered end side of the light guide, the number of times it intersects with the light oscillation part 1 increases, and the light introduced into the light guide 2 can be used more effectively. Note that the larger the angle intersecting the central axis O-0, the more light leaks from the tapered surface 2C, so the tapered surface 2C
When formed on the reflective surface, no light leaks from the light guide 2, and the light introduced into the light guide 2 can be used more effectively.

Further, the central axis of the light guide 2 may be formed hollow only at the part where the light oscillation part 1 enters, but as shown in the figure, a wide cross-sectional area of the light guide 2 from the light emission end 1a of the light oscillation part 1 is formed. The space up to the end surface 2A may also be made into a hollow ID. In this way, light scattering within the light guide 2 is eliminated, and the light emitted from the light oscillation section 1 can be radiated more effectively. And more.

If the wall surface of this hollow part ID is made into a reflective surface IE, the excitation light from the optical fiber 4 and the laser light from the oscillation part 1 can be completely separated, and interference between them can be eliminated. Alternatively, the side 1b in the figure may be an incompletely reflecting surface, and the laser beam may be emitted from the tapered tip of the tapered light guide 2.

As is clear from the above explanation, according to the present invention, the light transmitted through the optical fiber can be more effectively supplied to the optical oscillation unit, and a more effective and more powerful laser can be generated. Can generate light.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of main parts for explaining an embodiment of an optical oscillator according to the present invention, and FIG. 2 is a configuration diagram for explaining an example of an optical oscillation unit previously proposed by the present applicant. FIG. 3 is a diagram showing the refractive index distribution of the light guide used in the implementation of the present invention;
FIG. 4 is a diagram showing an example of a sunlight collecting device suitable for use in carrying out the present invention, and FIG. 5 is a diagram illustrating the operating principle for introducing light of a desired wavelength component into an optical fiber. This is a diagram for DESCRIPTION OF SYMBOLS 1... Light oscillation part, 2... Light guide, 3... Reflection film,
4...Optical fiber. Section 1, Figure 2, Figure 3 (a) (b); Folding X Figure 4

Claims (1)

[Claims] 1. A tapered light guide, a columnar light oscillating part having an excited substance disposed along the central axis of the light guide, and a large cross-sectional area side of the tapered light guide. It consists of a large number of optical fibers each having a light emitting end face bonded to the end thereof, and the light emitted from the end face of the optical fiber is reflected by the columnar tapered surface and crosses the light oscillating part. optical oscillator. 2. The optical oscillator according to claim 1, wherein the optical oscillator is disposed on the tapered side of the optical guide. 3. The optical oscillator according to claim 1 or 2, wherein the tapered surface and the tapered end surface of the light guide are formed as reflective surfaces. 4. Any one of claims 1 to 3, wherein the light emitted from one end of the columnar light oscillation section is emitted from the wide cross-sectional area side of the light guide. The optical oscillator described in . 5. According to any one of claims 1 to 4, wherein the center portion of the light guide from the light emitting end face of the light oscillating part to the light emitting end face of the light guide is hollow. The optical oscillator described. 6. The optical oscillator according to claim 5, wherein the hollow wall surface is formed as a reflective surface.