JPH1065260A - Solid-state laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolored solid-state laser, which switches easily to a plurality of kinds of wavelengths for laser beams and can output the laser beams, while the structure of the solid laser is compact and simple. SOLUTION: A rare earth-containing chloride, which makes a wavelength upward conversion light L1 from an excitation light source 1 and can emit the light L1 as a plurality of kinds of peak wavelengths of lights, is used as a laser active medium 2. A filter 4a, which transmits selectively the specified one peak wavelength of the light only from among the plurality of kinds of the peak wavelengths of these lights, is arranged on an optical path between the medium 2 and the optical oscillator mirror on one side of optical oscillator mirrors 3a and 3b, and the specified one peak wavelength of the light L2 is selected and a laser oscillation is made to take place for outputting. It is preferable to use a filter unit 6 of a structure, wherein filters are prepared by the number of lights of peak wavelengths to be selected and only one of the filters can be arranged in a freely exchangeable state on the optical path from among these filters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength-upconverting laser device among solid-state laser devices, and more particularly to a device capable of switching and outputting multicolor laser light with one device.

[0002]

2. Description of the Related Art In recent years, in response to demands for multicolor display in information and display, or demands in fields such as photochemical reactions and medical treatment, various colors such as red and green in the visible light region, and further from blue to ultraviolet light. Short wavelength laser,
It is strongly sought for various purposes.

[0003] Actually, those that generate red, green, and blue laser beams include various solid-state lasers (such as Nd: YAG).
There are lasers utilizing HG light, and gas lasers such as He-Ne laser and Ar laser. In addition, an up-conversion laser (which generates visible laser light from infrared excitation light by multi-step excitation of rare earth ions contained in a laser active medium), which is one form of a solid-state laser device, is also an infrared laser. Attention has been paid to a technique capable of oscillating various visible laser lights from red to blue by exciting with an inexpensive semiconductor laser that emits light.

[0004]

However, these laser devices are all monochromatic, and when laser beams of a plurality of wavelengths are required, these laser devices are replaced by the number of types of required wavelengths. Prepared separately or O
There has been no choice but to prepare a large and expensive device such as a PO that can emit laser beams of a plurality of wavelengths by one unit.

An object of the present invention is to provide a multicolor solid-state laser device capable of easily switching and outputting a plurality of wavelengths of laser light with a single device while having a compact and simple structure. That is.

[0006]

A solid-state laser device according to the present invention has the following features. (1) In a wavelength-upconverting laser device, a rare-earth-containing chloride capable of up-converting light from an excitation light source and emitting light of a plurality of peak wavelengths is used as a laser active medium. A solid-state laser characterized by being provided with a filter for selectively transmitting only one specific peak wavelength light, and for selectively transmitting the specific one peak wavelength light by laser oscillation and output; apparatus.

(2) The solid-state laser device includes the excitation light source, the laser active medium, two optical resonator mirrors sandwiching the laser active medium, and a filter device. Has a filter of
The filter according to claim 1, wherein the filter is one selected from the plurality of filters, and the filter device arranges the selected one filter on an optical path between the laser active medium and one of the optical resonator mirrors. Then, it has a structure in which another filter can be freely replaced with a filter on the optical path and arranged on the optical path, and each of the plurality of filters has a specific peak among the plurality of peak wavelength lights. Wavelength light is selectively transmitted, the specific peak wavelength light transmitted by each filter is different from each other for each filter, and two optical resonator mirrors are selected by the plurality of filters. (1) The solid-state laser device according to the above (1), which can oscillate all the peak wavelength lights.

(3) In the above-mentioned filter device, a structure in which a filter on the optical path and another filter are freely exchanged has a structure in which a plurality of filters are rotatably moved around one rotation axis placed outside the optical path. The solid-state laser device according to (2), wherein the filters are moved one by one on the optical path and exchanged.

(4) A structure in which a plurality of filters are rotatably moved and exchanged about one rotation axis placed outside the optical path, the rotation plate being rotated about a rotation axis parallel to the optical path, The solid-state laser device according to the above (3), having a structure having a plurality of filters arranged on the same circumference on the rotating plate.

(5) In the above-mentioned filter device, a structure in which a filter on an optical path and another filter are freely exchanged is such that a plurality of filters are arranged on the same straight line and move linearly. The solid-state laser device according to the above (2), wherein the laser device is configured to be moved one by one on an optical path and exchanged.

(6) The solid-state laser device according to any one of the above (1) to (5), wherein the light emitted by laser oscillation is light having a wavelength in the red, green, and blue regions.

(7) The rare earth-containing chloride of the laser active medium is Er-containing chloride crystal or Er-containing chloride glass, and the wavelength of light from the excitation light source is 790 nm to 84 nm.
0 nm, 965 nm-985 nm, or 1500 nm
The solid-state laser device according to any one of the above (1) to (6), which has one or more wavelengths selected from a range of from 1 to 1550 nm.

(8) Er-containing chloride crystals are composed of ErBa ₂
Cl ₇ crystal, wherein the wavelength of light from the excitation light source is 96
The solid-state laser device according to the above (7), which has a thickness of 5 nm to 985 nm.

(9) The filter according to any one of the above (1) to (8), wherein the transmittance of the filter is adjusted so as to make the output intensity of the laser beam at each peak wavelength light uniform. The solid-state laser device as described in the above.

[0015]

In the multicolor solid-state laser device according to the present invention, a rare-earth-containing chloride capable of up-converting light from an excitation light source and emitting light having a plurality of peak wavelengths is used as a laser active medium. The peak wavelength light is light whose light intensity shows a peak in a narrow wavelength region around a specific wavelength, and the peak portion is counted as one. From among the plurality of peak wavelength lights emitted after the wavelength up-conversion, filters capable of selectively transmitting only one peak wavelength light are prepared by the number of peak wavelength lights to be selected. Among them, a filter device having a structure in which only one of them can be moved on the optical path so as to be exchangeable with the remaining filters is used.

With the above configuration, only the peak wavelength light to be selected out of the plurality of peak wavelength lights emitted from the excited laser active medium can be easily selected by using the filter device. The laser can be oscillated by the resonator mirror and output. Therefore, the laser light of a plurality of wavelengths can be easily switched even though it is a single solid-state laser device having a small and simple configuration sharing a common excitation light source, one laser active medium, and a pair of optical resonator mirrors. It is a device that can output.

Further, the plurality of peak wavelength lights emitted from the laser active medium usually have different light intensities for each wavelength, whereby the laser output also has a different light intensity for each wavelength. When it is desired to output laser beams of the respective wavelengths with the same intensity, the light transmittance of the filter may be adjusted in accordance with the emission intensity of each peak wavelength light from the laser active medium. In other words, by lowering the light transmittance of a filter of a wavelength having a high light intensity, a multicolor laser device having a uniform output light intensity at each wavelength can be obtained. However, the uniformity here includes a substantially uniform state having an error in practical use.

If a laser emitting medium emitting peak wavelength light in the red, green, and blue wavelength ranges is used, a full-color laser device can be obtained. In this case, it is more preferable to adjust the transmittance of the filter in accordance with the intensities of the red, green, and blue peak wavelength lights because a full-color laser device in which the output intensities of the respective colors are substantially uniform to each other can be obtained. Of course, in applications where uniformity of the output intensity of each color is not required, a filter having a similar transmittance may be used.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in more detail. FIG. 1 is a diagram showing an example of a multicolor solid-state laser device according to the present invention. In the figure, 1 is an excitation light source, 2 is a laser active medium, 3a and 3b are optical resonator mirrors, and 6 is a filter device. The laser active medium 2 is
This is a rare earth-containing chloride that can convert light L1 from the excitation light source 1 into a wavelength-upconverted light and emit it as light having a plurality of peak wavelengths. The optical resonator mirrors 3a and 3b can all oscillate the peak wavelength light selected by the filter device described later. The filter device 6 includes a plurality of filters. In the example of the figure, an alternative configuration including two filters 4a and 4b is shown for simplicity, and the selected filter 4a is provided between the laser active medium and one optical resonator mirror. Are arranged on the optical path. The filters are configured to be easily exchangeable with each other. In addition, one filter selectively transmits only one peak wavelength light from a plurality of peak wavelength lights emitted after being wavelength-upconverted and emitted by the laser active medium. The wavelengths are different. It should be noted that illustration of other auxiliary devices is omitted.

In the multicolor solid-state laser device having the above structure,
When the excitation light L1 emitted from the excitation light source 1 enters the laser active medium 2, the laser active medium 2 is excited and emits light of various wavelengths. In the present invention, particularly, the peak wavelength light whose wavelength is up-converted is targeted.
Only the peak wavelength light L2 selectively transmitted by the filter 4a disposed on the optical path by the filter device 6 out of the wavelength-upconverted peak wavelength light is laser-oscillated by the optical resonator mirrors 3a and 3b, and externally emitted. Laser light L3
Is output as Therefore, only by exchanging the filters 4a and 4b of the filter device 6, the peak wavelength light corresponding to them is selected, and the output of the laser light of a different wavelength is obtained.

As the rare earth-containing chloride used in the laser active medium, a substance which converts the excitation light into wavelengths and emits a plurality of types of light having a shorter wavelength is used. Among the rare earth-containing chlorides, as disclosed in JP-A-7-97572, Er-containing chloride crystals are preferable, and in particular, ErBa ₂ C
l ₇ single crystals, when irradiated with excitation light having a wavelength 965Nm～985nm, by the wavelength up-conversion, emits red, green, the peak wavelength light in the blue wavelength range, suitable materials for the construction of the above full-color laser device It is.

The excitation light source may be any light source capable of causing light of a predetermined wavelength required as excitation light to be incident on the laser active medium with power required for laser oscillation. Specific examples include a near-infrared semiconductor laser and an Nd: YAG laser excited by the semiconductor laser. Among these, a semiconductor laser is most preferable for downsizing. Further, the excitation light source may be a continuous oscillation or a pulse oscillation.

The individual filters of the filter device need only be capable of selectively transmitting only one of a plurality of peak wavelength lights emitted from the laser active medium. Such filters are prepared by the required number of wavelengths, and have such a structure that they can be interchangeably arranged on the optical path. The structure of such a filter device includes manual and automatic
Although not particularly limited, the following structures are preferred. (A) A structure in which a plurality of filters to be exchanged move on an optical path one by one by being rotationally moved around one rotation axis placed outside the optical path and exchanged. (B) a plurality of filters to be replaced are arranged on the same straight line,
A structure that is moved on the optical path one by one and exchanged.

FIG. 1 shows a specific example of the structure (a).
And a rotation axis Y outside the optical path and parallel to the optical path.
Replacement of the filter by a rotating plate that rotates around the center. The filters 4a and 4b are arranged on a predetermined circumference of the rotating plate 5, that is, on a circumference intersecting the optical path of the laser oscillation, and one of these filters is formed by rotating the rotating plate 5 around the rotation axis Y. Each is moved on the optical path and exchanged. In order to prevent light passing through the filter from being blocked by the rotating plate, a structure in which the filter is provided through the rotating plate, a structure in which the rotating plate is transparent to light emitted from the laser active medium, and the like can be given. The material of the rotating plate is not limited, but opaque materials include aluminum, and transparent materials include synthetic quartz.

As a specific example of the above structure (b), a filter to be exchanged is linearly arranged on a plate of a predetermined length, and this plate is used as in the operation of a film with respect to the optical axis of a projector. And a structure in which a filter is replaced by linearly moving in a direction perpendicular to the optical axis of laser oscillation. The structure for preventing light passing through the filter from being blocked by the plate is the same as that of the rotating plate.

Examples of filters capable of transmitting only one peak wavelength light include a band-pass filter, a Fabry-Perot etalon, and a birefringent filter. As described above, when it is desired to equalize the output intensity for each peak wavelength light, the light transmittance of the filter is adjusted according to the intensity of the peak wavelength light of the laser active medium. That is, for a peak wavelength light having a high light intensity, the transmittance of a filter for selecting the wavelength is lowered so that the light intensity becomes substantially the same as that of the other peak wavelength lights having a low light intensity. Light output is made uniform.

The filter may be provided between the laser active medium and the optical resonator mirror, and may be provided on either the excitation light incident side or the laser light emission side with respect to the laser active medium. For example, in the example of FIG. 1, the filter is a laser active medium 2 and an optical resonator mirror 3a on the excitation light incident side.
May be provided between them.

It is assumed that the pair of optical resonator mirrors can oscillate at least the peak wavelength light selected by the filter. As a structure of such an optical resonator mirror, a structure using a band-pass filter that allows only excitation light to pass therethrough can be cited. The following are examples of the mode of the optical resonator mirror. . As illustrated in FIG. 1, two optical resonator mirrors 3
a and 3b are provided at an interval with respect to the laser active medium. . As illustrated in FIG. 3, two optical resonator mirrors 3
a, 3b, the optical resonator mirror on the side where the filter 4 is not interposed (3a in FIG. 3 (a), 3b in FIG. 3 (b))
Is a mirror formed directly on the end face of the laser active medium by coating or the like.

[0029]

EXAMPLE An experiment was conducted to confirm whether or not the laser oscillation wavelength can be actually selected, using the above-described configuration and the configuration of the multicolor solid-state laser device shown in FIG. However, in the present embodiment, there are three types of peak wavelength light to be selected. Accordingly, the number of filters on the rotary plate of the filter device was also set to 3, and three filters were arranged at 120 ° intervals on the same circumference of the rotary plate surface. ErBa ₂ as laser active medium
Cl ₇ single crystal is used, and a center wavelength of 982 n
m, a CW semiconductor laser having a maximum output of 1 W is irradiated as excitation light, and light emitted from the laser active medium has a spectrum having peaks in red, green, and blue wavelength ranges as shown in FIG. Met. Among these many peaks, 46 emitted by wavelength up-conversion
Three types of wavelengths of 0 nm, 550 nm, and 640 nm were selected, and three types of band-pass filters that transmit only each wavelength were prepared. Further, as the optical resonator mirror, a mirror having a high reflection coating in the range of 400 to 700 nm was prepared, and the structure was such that laser oscillation could be performed at any wavelength.

From the semiconductor laser as the excitation light source, 2
When one of the two optical resonator mirrors is transmitted and the laser active medium is irradiated with the excitation light, a wavelength of 4 if a filter that transmits only 460 nm is arranged on the optical path.
A 60 nm laser beam oscillates. Similarly, a 550 nm laser beam oscillates a 550 nm laser beam, and a 640 nm filter oscillates a 640 nm laser beam. It was confirmed that three types of laser beams were obtained. Further, as is clear from the graph of FIG. 2, among the peak wavelength lights emitted by the laser up-converted by the laser active medium, the peak wavelength light of 460 nm has lower light intensity than the peak wavelength light of other wavelengths. . In this embodiment,
The transmittance of a filter that transmits light having a peak wavelength of 550 nm and 640 nm was adjusted to be low. Thus, it was confirmed that the output of the emitted laser light could be made equal to that of the 460 nm laser light without changing the intensity of the excitation light for each peak wavelength light.

[0031]

As described above, the multicolor solid-state laser device of the present invention converts a plurality of peak wavelength lights emitted from one laser active medium by wavelength up-conversion into a simple filter exchange using a filter device. As a result, laser beams of a plurality of wavelengths can be obtained, so that it is not necessary to separately prepare laser devices that emit laser beams of each wavelength. In addition, since the same excitation light source, one laser active medium, and a pair of optical resonator mirrors are shared, the apparatus does not become large. Therefore, the configuration of the system when it is necessary to properly use the multicolor laser beams is facilitated. Even if the peak wavelength light emitted from the laser active medium has a variation in light intensity, by optimizing the transmittance of the filter, laser light having a constant excitation light and uniform intensity at any wavelength can be obtained. It is possible to output.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a multicolor solid-state laser device according to the present invention.

FIG. 2 shows a center wavelength of 98 with respect to ErBa ₂ Cl ₇ single crystal.
FIG. 4 is a graph showing a spectrum of emitted fluorescence when CW semiconductor laser light of 2 nm is irradiated as excitation light.

FIG. 3 is a diagram showing an embodiment of an optical resonator mirror according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Excitation light source 2 Laser active medium 3a, 3b Optical resonator mirror 4a, 4b Filter 5 Rotating plate 6 Filter device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Taniguchi 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Electric Cable Industry Co., Ltd. Itami Works (72) Inventor Hiroyuki Shiraishi 1-297, Kitabukurocho, Omiya-shi, Saitama Mitsubishi Materials Inside Research Institute Co., Ltd.

Claims (9)

[Claims] 1. A wavelength-upconverting laser device, wherein a rare-earth-containing chloride capable of up-converting light from an excitation light source and emitting as a plurality of peak wavelength lights is used as a laser active medium, and the plurality of peak wavelength light A filter for selectively transmitting only one specific peak wavelength light is provided, and the selectively transmitted specific one peak wavelength light is laser-oscillated and output. Solid state laser device. 2. The solid-state laser device, comprising: the excitation light source; the laser active medium;
One optical resonator mirror and a filter device, wherein the filter device has a plurality of filters, the filter according to claim 1 is one selected from the plurality of filters, and the filter device is A structure in which one selected filter is arranged on the optical path between the laser active medium and one of the optical resonator mirrors, and the other filter is freely exchangeable for the filter on this optical path and arranged on the optical path. Each of the plurality of filters is to selectively transmit a specific one peak wavelength light from the plurality of peak wavelength lights, and the specific peak wavelength light transmitted by each filter is , Each of the filters being different from one another, the two optical resonator mirrors emitting laser light for all of the peak wavelength light selected by the plurality of filters. Solid-state laser apparatus according to claim 1, wherein it is capable to. 3. A structure in which a filter on the optical path and another filter in the filter device are freely exchanged, wherein a plurality of filters are rotatably moved around one rotation axis placed outside the optical path. 3. The solid-state laser device according to claim 2, wherein the filters are moved one by one on the optical path and exchanged. 4. A structure in which a plurality of filters are rotatably moved and exchanged about one rotation axis placed outside the optical path, the rotation plate rotating about a rotation axis parallel to the optical path, and 4. The solid-state laser device according to claim 3, wherein the solid-state laser device has a structure having a plurality of filters arranged on the same circumference on a rotating plate. 5. A structure in which a filter on an optical path and another filter are freely exchanged in the filter device, wherein a plurality of filters are arranged on the same straight line and move linearly so that the filter is one. 3. The solid-state laser device according to claim 2, wherein the solid-state laser device has a structure in which the laser beam is moved one by one on an optical path and exchanged. 6. The laser oscillation and output light is red,
The solid-state laser device according to any one of claims 1 to 5, wherein the light has a wavelength in a green or blue region. 7. The rare earth-containing chloride of the laser active medium,
Er-containing chloride crystal or Er-containing chloride glass, wherein the wavelength of light from the excitation light source is 790 nm to 840 nm.
m, 965 nm to 985 nm, or 1500 nm to 1
7. The solid-state laser device according to claim 1, wherein the wavelength is one or more wavelengths selected from 550 nm. 8. An Er-containing chloride crystal comprising ErBa ₂ Cl
₇ crystals, and the wavelength of light from the excitation light source is 965n
The solid-state laser device according to claim 7, wherein m is from 985 nm. 9. The solid-state laser according to claim 1, wherein the filter has a transmittance adjusted so as to make the output intensity of the laser light at each peak wavelength light uniform. apparatus.