JPH098387A - Laser amplifier - Google Patents

Abstract

PURPOSE: To amplify two laser lights having different wavelength simultaneously using a single laser amplifier. CONSTITUTION: When a laser light P comprising two components of different wavelength A, B superposed on an identical optical axis enters into a chamber 10, the laser light P is diffracted through a first diffraction grating 12 to respective optical paths for wavelength A and B before entering into a pumping region 11. The laser light components having wavelength A, B are amplified when passing through the pumping region 11 and then they are passed through a second diffraction grating 14 before being outputted on the same axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser amplifier applied to a laser radar light source for measuring atmospheric concentrations of ozone, water vapor and the like using laser light.

[0002]

2. Description of the Related Art In recent years, atmospheric concentrations of ozone, water vapor, volatile organic compounds, etc. have been actively measured. One of the methods for measuring the atmospheric concentration is a differential absorption method using laser light. This differential absorption method is to measure and analyze using laser light having two wavelengths, a wavelength A and a wavelength B at which absorption of molecules to be measured is large.

FIG. 5 is a block diagram of a laser radar light source to which such a differential absorption method is applied. Diffraction gratings 3 and 4 and output mirrors 5 and 6 are arranged in the two laser tubes 1 and 2, respectively. One of the diffraction gratings 3 is for selecting the wavelength A, and the other diffraction grating 4 is for selecting the wavelength B.

Therefore, the laser beam output from one laser tube 1 is output as a laser beam of wavelength A by diffraction by the diffraction grating 3, and the laser beam output from the other laser tube 2 is output by the diffraction grating 4. It is output as laser light of wavelength B by diffraction.

The laser beams of wavelengths A and B are reflected by the mirrors 7 and 8, respectively, and are emitted into the atmosphere as coaxial laser beams. The laser light of each wavelength A and B scattered and returned in the atmosphere is separately received by the telescope, and the amount of received light, that is, the amount of absorption of each wavelength A and B is detected to detect ozone and water vapor in the atmosphere. The concentration is measured.

By the way, in such a laser radar light source, it is desired to increase the output of the laser in order to improve the measurement accuracy. Therefore, a laser amplifier is used to increase the laser output. That is, each laser amplifier is arranged for each laser beam of two wavelengths A and B,
These laser amplifiers separately amplify the laser lights of wavelengths A and B, but this requires two laser amplifiers.

When laser amplification is performed using a single laser amplifier, coaxial two wavelength laser beams are simultaneously incident. As a result, the two-wavelength laser light travels on the same optical path in the pumping region, and the amplification factor for the laser light of each wavelength decreases.

[0008]

As described above, if each laser beam of each wavelength A and B is amplified separately, two laser amplifiers are required. Further, when laser amplification is performed using one laser amplifier, laser light of each wavelength travels on the same optical path in the excitation region, and the amplification factor for each laser light becomes low. Therefore, it is an object of the present invention to provide a laser amplifier capable of simultaneously amplifying at least two wavelengths of laser light with one unit.

[0009]

According to a first aspect of the present invention, in a laser amplifier for amplifying and outputting a laser beam in which light beams having different wavelengths are superposed on the same optical axis, the laser beam is sent to each optical path for each wavelength. A wavelength spectroscopic optical system that separately enters the pumping region, and an output optical system that returns each laser beam of each wavelength that has traveled through the pumping region and is amplified to the same axis and output the laser beam,
It is a laser amplifier which has the above-mentioned object and is intended to achieve the above object.

According to the second aspect, the wavelength spectroscopic optical system is a laser amplifier which is a diffraction grating. According to claim 3, the output optical system is a laser amplifier which is a diffraction grating. According to a fourth aspect of the present invention, there is provided a laser amplifier including a folding optical system that causes respective laser beams of different wavelengths traveling in different optical paths in the pumping region to travel back in different optical paths in the pumping region.

[0011]

According to the first aspect, when the laser light in which the light beams having different wavelengths are superposed on the same optical axis is incident, the laser light is divided into each optical path for each wavelength by the wavelength spectroscopic optical system, and the excitation region is obtained. Incident on. Then, each laser beam of each wavelength that has traveled through this excitation region and is amplified is returned to the same axis by the output optical system and output. In this way, by advancing the laser light of each wavelength in the excitation region through separate optical paths, one laser light of at least two wavelengths can be simultaneously amplified.

According to the second aspect, the coaxial laser light of at least two wavelengths is divided into each optical path for each wavelength by the diffraction grating and is incident on the excitation region. According to the third aspect, the laser lights of the respective wavelengths that have traveled through the pumping region and are amplified are returned to the same axis by the diffraction grating and output.

According to the fourth aspect of the present invention, the laser lights of different wavelengths which travel in the pumping region in different optical paths are reflected and propagated in different optical paths in the pumping region by the folding optical system to be laser-amplified.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a laser amplifier that amplifies two wavelengths simultaneously. The chamber 10 is filled with an excitation medium, for example, a mixed gas for CO ₂ laser. Although not shown, a pair of main electrodes facing each other is arranged in the chamber 10, and the excitation medium is excited by application of a high voltage between the main electrodes to form an excitation region 11.

The laser light P amplified by this laser amplifier is a CO ₂ laser light in which light beams having different wavelengths are superposed on the same optical axis, for example, a wavelength A (9.50 μm),
Each laser beam of wavelength B (9.59 μm) is superposed on the same optical axis.

This laser light P enters the chamber 10 outside the excitation region 11 in the chamber 10. A first diffraction grating 12 as a wavelength spectroscopic optical system is arranged on the optical path of the laser light P in the chamber 10. The first diffraction grating 12 has a function of dividing each laser beam of two wavelengths A and B into each optical path of each wavelength A and B and making it enter the excitation region 11.

In the chamber 10, a folding mirror 13 is arranged in the diffraction direction of the first diffraction grating 12, and a second diffraction grating 14 as an output optical system is arranged in the laser reflection direction of the folding mirror 13. Are arranged.

The turn-back mirror 13 turns back each laser beam of each wavelength A and B, which has traveled in the pumping region 11 in another optical path, and causes it to travel again in each different optical path in the pumping region 11.

The second diffraction grating 14 has a function of returning the laser lights of the respective wavelengths A and B, which have traveled through the excitation region 11 and are amplified, to the same axis and output the same. Next, the amplification action of the laser amplifier configured as described above will be described.

When the laser light P of two coaxial wavelengths A and B enters the chamber 10, the laser light P enters the first diffraction grating 12 and, as shown in FIG.
It is divided into

Here, the wavelength A is λ _A , the wavelength B is λ _B , the incident angle of the laser light P on the first diffraction grating 12 is i, and the wavelength A is
Where the diffraction angle of the laser light is θ _A , the diffraction angle of the laser light of wavelength B is θ _B , the groove width of the first diffraction grating 12 is d, and the order is m, the incident angle i of the laser light P and the Wavelength diffraction angle θ _A ,
The relationship with θ _B is expressed by the following equation.

_M · λ _A = d (sini ± sin θ _A ) (1) m · λ _B = d (sini ± sin θ _B ) (2) Here, when the diffraction order m is 1, Diffraction angle θ
_A and θ _B are as follows.

[0023]

[Equation 1]

As described above, the diffraction angles θ _A and θ _B are different depending on the two wavelengths A and B, and the laser beams of these wavelengths A and B are separated. The respective laser lights of the wavelengths A and B travel in the pumping region 11 through different optical paths, and are reflected by the folding mirror 1.
3, the light is reflected by the folding mirror 13 and travels again in the excitation region 11 through different optical paths.

As described above, the laser lights of the two wavelengths A and B are amplified as they travel through the pumping region 11. The amplified laser lights of the respective wavelengths A and B enter the second diffraction grating 14 and travel on the coaxial optical path.

That is, as shown in FIG. 3, the second diffraction grating 14 is arranged so that the laser beams of the respective wavelengths A and B are incident at the incident angles θ _A and θ _B , respectively. The width d of the groove of the second diffraction grating 14 is the same as the width d of the groove of the first diffraction grating 12.

Here, in the second diffraction grating 14, assuming that the diffraction angles of the laser beams of the respective wavelengths A and B are θ _A ′ and θ _B ′, the incident angles θ _A and θ _B and the diffraction angle θ _A ′. , Θ _B ′ is expressed by the following equation.

Λ _A = d (sin θ _A ± sin θ _A ′) (5) λ _B = d (sin θ _B ± sin θ _B ′) (6) These expressions (5) and (6) are added to the above expression (3) ( Substituting 4), the relationship of θ _A ′ = i (7) θ _B ′ = i (8) is obtained.

That is, the laser beams Q _A and Q _B of the respective wavelengths A and B diffracted by the second diffraction grating 14 have the same diffraction angles θ _A ′ and θ _B ′ and travel in the coaxial optical path. It will be.

In FIG. 3, the diffraction angles θ _A ′ and θ _B ′ are shown as different angles for the sake of explanation. Therefore, the amplified laser lights Q _A and Q _B of the wavelengths A and B travel along the coaxial optical path and are output from the chamber 10 as amplified laser lights Q to the outside.

As described above, in the above-described embodiment, when the laser light P of two wavelengths A and B is incident, the laser light P of these two wavelengths is passed by the first diffraction grating 12 to each optical path of each wavelength A and B. And is incident on the excitation region 11,
Since the laser lights of the respective wavelengths A and B which have traveled through 1 and are amplified are returned coaxially by the second diffraction grating 14 and output, the two wavelengths A, B are output by one laser amplifier.
Each laser beam of B can be amplified at the same time, and the laser beams of these wavelengths A and B can be outputted with a large amplification factor by advancing through different optical paths in the excitation region 11.

If this laser amplifier is applied to a laser radar light source for measuring the concentration of ozone, water vapor, etc., it is possible to irradiate a high-power laser on a measurement target and improve the measurement accuracy.

FIG. 4 is an overall configuration diagram applied to a laser radar light source for measuring the concentration of ozone, water vapor and the like. Diffraction gratings 3 and 4 and output mirrors 5 and 6 are arranged in the two laser tubes 1 and 2, respectively. One of the diffraction gratings 3 is for selecting the wavelength A, and the other diffraction grating 4 is for selecting the wavelength B.

The laser beam output from one laser tube 1 is output as a laser beam of wavelength A by the diffraction by the diffraction grating 3, and the laser beam output from the other laser tube 2 is output by the diffraction grating 4. It is output as laser light of wavelength B.

The laser lights of the wavelengths A and B are reflected by the mirrors 7 and 8, respectively, and enter the chamber 10 of the laser amplifier as the coaxial laser light P. When this laser light P enters the chamber 10, this laser light P
Enters the first diffraction grating 12 and is divided into wavelengths A and B as shown in FIG.

Each of the laser beams having the wavelengths A and B travels in the excitation region 11 through different optical paths, reaches the folding mirror 13, is folded back by the folding mirror 13, and again in the excitation region 11 through different optical paths. proceed.

The laser lights of these two wavelengths A and B are
Each of them is amplified by traveling through the excitation region 11. The amplified laser lights of the respective wavelengths A and B enter the second diffraction grating 14 as shown in FIG. 3 and travel on the coaxial optical path.

Therefore, the amplified laser lights Q _A and Q _B of the wavelengths A and B, respectively, travel in the coaxial optical path and are output from the chamber 10 as amplified laser light Q to the outside and are irradiated into the atmosphere. .

The laser light of each wavelength A and B scattered and returned in the atmosphere is separately received by the telescope, and the amount of received light, that is, the amount of absorption of each wavelength A and B is detected to detect ozone and ozone in the atmosphere. The concentration of water vapor etc. is measured.

With such a laser radar light source,
Laser light of two wavelengths A and B can be amplified at the same time to irradiate high-power laser light into the atmosphere, and accuracy of measurement of atmospheric concentrations of ozone, water vapor, volatile organic compounds, etc. can be increased.

The present invention is not limited to the above-mentioned embodiment but may be modified as follows. For example, in the above-mentioned one embodiment, the laser lights of the two wavelengths A and B are amplified and output, but the present invention can also be applied to the amplification and output of laser lights of two or more wavelengths.

Further, the amplification of the laser light is not limited to the one-stage amplification using one laser amplifier, and a plurality of laser amplifiers may be arranged to perform the multiple-stage amplification.
Alternatively, a plurality of folding mirrors 13 may be arranged in combination, and each laser beam of each wavelength may be diffracted back into the excitation region 11 to increase the amplification factor. Further, the pumping medium of the laser amplifier is not limited to the mixed gas for CO ₂ laser, but a solid medium such as titanium-sapphire laser or a liquid pumping medium may be used.

[0043]

As described above in detail, according to the present invention, 1
A laser amplifier capable of simultaneously amplifying at least two wavelengths of laser light on a stand can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a laser amplifier according to the present invention.

FIG. 2 is a schematic diagram showing an operation of dividing a laser beam by a wavelength of a first diffraction grating.

FIG. 3 is a schematic diagram showing an operation of coaxially arranging laser light of each wavelength by a second diffraction grating.

FIG. 4 is an overall configuration diagram applied to a laser radar light source.

FIG. 5 is a configuration diagram of a laser radar light source.

[Explanation of symbols]

10 ... Chamber, 11 ... Excitation region, 12 ... First diffraction grating, 13 ... Folding mirror, 14 ... Second diffraction grating.

Claims (4)

[Claims] 1. A laser amplifier which amplifies and outputs laser light in which light beams having different wavelengths are superposed on the same optical axis, wherein the laser light is divided into respective optical paths for the respective wavelengths and is incident on an excitation region. A laser amplifier comprising: an optical system; and an output optical system that returns each laser beam of each of the wavelengths, which has traveled in the pumping region and is amplified, back to the coaxial and outputs the laser beam. 2. The laser amplifier according to claim 1, wherein the wavelength spectroscopic optical system is a diffraction grating. 3. The laser amplifier according to claim 1, wherein the output optical system is a diffraction grating. 4. A turn-back optical system for turning back each laser beam for each wavelength, which travels in a different optical path in the pumping region, to a different optical path in the pumping region. 1. The laser amplifier according to 1.