Sequence pulse optical parametric oscillation laser for combustion field measurement

Abstract

The invention provides a sequence pulse optical parametric oscillation laser for combustion field measurement. The sequence pulse optical parametric oscillation laser for combustion field measurement comprises an optical fiber laser, a solid amplifier, an optical parametric oscillator and a frequency doubling and light splitting unit. The fiber laser is used for continuously outputting pulse laser as seed laser, and the repetition frequency of the seed laser can be controlled and adjusted. The seed laser is configured to enter a solid state amplifier capable of outputting a sequence pulse laser. The sequence pulse laser is configured to enter an optical parametric oscillator to change wavelength. And the frequency doubling and light splitting unit is configured in a light path formed by the fiber laser, the solid amplifier and the optical parametric oscillator, and can adjust the frequency of the laser, so that the laser of 283nm can be finally output. The fiber laser is used as a seed laser of the front end, pulse energy storage amplification is achieved through the solid amplifier, sequence pulse output can be achieved, and the pulse interval is convenient to adjust.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a sequence pulse optical parametric oscillator laser for combustion field measurement. Background Art

[0002] In the combustion field, there are many chemical components involved in the combustion process, such as OH and CH 2 O, etc. In order to measure these components, the PLIF (planar laser induced fluorescence) method can be used to use a laser of a specific wavelength to interact with these chemical components to stimulate fluorescence spectra. Then, by measuring these fluorescence spectra with a camera, the distribution of chemical components in the combustion field can be depicted.

[0003] In the measurement of combustion fields, lasers with a repetition frequency of about 10 Hz are mainly used, that is, the pulse interval is 100 ms. The frequency of 10 Hz is suitable for long-term monitoring, but such a setting cannot capture the change process of chemical components within 100 ms. As the requirements for the precision of observing the change process continue to increase, the pulse interval needs to be reduced. However, increasing the repetition frequency of the laser to reduce the pulse interval will cause the laser to generate a lot of heat. At the same time, high repetition frequency lasers on the market usually have lower pulse energy.

[0004] Existing lasers can achieve laser pulse output with adjustable pulse intervals through pulse train Q-switching technology. Among them, electro-optical Q-switching is used for operation below 10kHz, and the pulse energy can reach the joule level. Acousto-optical Q-switching can be used for higher repetition frequencies, but the pulse width is relatively wide.

[0005] More specifically, if Figure 1 As shown, the inventors know of a technology for directly generating a series of pulses in a resonant cavity. A square wave IGBT (insulated gate bipolar transistor) power supply is used to discharge a xenon lamp to pump the gain medium to store energy. Multiple Q-switching in the resonant cavity achieves laser pulse output with an adjustable pulse interval of 100 to 300 μs. However, as mentioned above, it is difficult to reduce the pulse interval when the electro-optical Q-switching reaches 10kHz. Acousto-optical Q-switching can increase the repetition frequency (reduce the pulse interval), but the pulse width of the output laser is relatively wide. The solution is relatively complicated. After modifying the interval, the resonant cavity and the amplifier must be adjusted accordingly.

[0006] Therefore, there is still room for improvement in lasers used for combustion field measurements. Summary of the invention

[0007] In order to solve or alleviate at least one of the problems mentioned in the background art, the present application provides a sequential pulse optical parametric oscillator laser for combustion field measurement.

[0008] The sequential pulse optical parametric oscillator laser for combustion field measurement provided in this application includes:

[0009] A fiber laser, used for continuously outputting pulsed laser light as a seed laser, wherein the repetition frequency of the seed laser light can be controlled and adjusted;

[0010] a solid-state amplifier, wherein the seed laser is configured to enter the solid-state amplifier, and the solid-state amplifier is capable of outputting a sequence of pulsed lasers;

[0011] an optical parametric oscillator, wherein the sequence of pulsed laser light is configured to enter the optical parametric oscillator to change the wavelength;

[0012] The frequency doubling and splitting unit is arranged in the optical path composed of the fiber laser, the solid-state amplifier and the optical parametric oscillator, and can adjust the frequency of the laser so that a 283nm laser can be output eventually.

[0013] In at least one embodiment, the sequential pulse optical parametric oscillator laser for combustion field measurement further includes a Faraday isolator, and at least one of the Faraday isolators is disposed between the fiber laser and the solid-state amplifier.

[0014] In at least one embodiment, the serial pulse optical parametric oscillator laser for combustion field measurement is provided with the following components in the order of light propagation path: the optical fiber laser, the first Faraday isolator, the first solid-state amplifier, the second Faraday isolator, the second solid-state amplifier, the first frequency doubling and spectroscopic unit, the optical parametric oscillator and the second frequency doubling and spectroscopic unit.

[0015] In at least one embodiment, the second solid-state amplifier is configured to output a 1064nm laser, the first frequency doubling and spectroscopic unit can output a 355nm laser, the optical parametric oscillator can output a laser including a 566nm laser, and the second frequency doubling and spectroscopic unit can generate the 283nm laser after frequency doubling the 566nm laser.

[0016] In at least one embodiment, the solid-state amplifier is a xenon lamp-pumped crystal amplifier.

[0017] In at least one embodiment, the solid-state amplifier is a diode-pumped crystal amplifier.

[0018] In at least one embodiment, the repetition frequency of the seed laser is configured to be adjustable within a range of 10 to 100 kHz.

[0019] In at least one embodiment, the repetition frequency of the seed laser is configured to be adjustable within a range of 100 to 10,000 kHz.

[0020] In at least one embodiment, the pulse width of the seed laser is configured to be in the range of 1 to 50 ns.

[0021] In at least one embodiment, the solid-state amplifier is configured to output the sequence of pulsed lasers with an energy of 0.1-1J.

[0022] The present application proposes to use a fiber laser as a front-end seed laser, realize pulse energy storage amplification through a solid amplifier, and realize sequential pulse output, and the pulse interval is conveniently adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. 4 is a schematic diagram showing a square wave pump multiple Q-switching technology known to the inventor.

[0024] Figure 2 A schematic structural diagram of a sequential pulse optical parametric oscillator laser for combustion field measurement according to an embodiment of the present application is shown.

[0025] Figure 3 A schematic diagram of a seed laser amplification process in a sequential pulse optical parametric oscillator laser for combustion field measurement according to an embodiment of the present application is shown.

[0026] Description of Reference Numerals

[0027] 100 Fiber Laser

[0028] 200 Optical Parametric Oscillator

[0029] 310 The First Faraday Isolator

[0030] 320 Second Faraday Isolator

[0031] 410 First Solid State Amplifier

[0032] 420 Second Solid State Amplifier

[0033] 510 First frequency doubling and spectroscopic unit

[0034] 520 Second frequency doubling and spectroscopic unit DETAILED DESCRIPTION

[0035] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0036] The inventors found that the fiber laser 100 can easily generate a high repetition frequency and adjust the repetition frequency conveniently, and can be used as a seed laser. The solid-state amplifier is suitable for pulse energy storage amplification and can easily amplify the energy of a single pulse. The advantages of the two components can be combined. The solid-state amplifier works for 10ms, for example, to obtain a 10ms sequence pulse, and the heat will not be too large, so that the details inside the 10ms combustion field can be observed.

[0037] More specifically, see Figure 2 The present application provides a sequential pulse optical parametric oscillator laser for combustion field measurement, which may include a fiber laser 100, a solid-state amplifier, an optical parametric oscillator 200 (OPO), a frequency doubling and a light splitting unit.

[0038] The fiber laser 100 is used to continuously output pulsed laser as a seed laser. The repetition frequency of the seed laser is convenient to be controlled and adjusted. The seed laser is configured to enter a solid-state amplifier, which can output a sequence of pulsed lasers. The timing relationship is as follows: Figure 3 shown.

[0039] That is, the present application proposes to use the fiber laser 100 as the front-end seed laser, and realize pulse energy storage amplification through a solid-state amplifier, so as to realize sequential pulse output, and the pulse width can reach the nanosecond level (for example, 8 to 10ns), and the interval between pulses can be easily adjusted. After modifying the repetition frequency of the seed laser, it is only necessary to adjust the voltage of the solid-state amplifier accordingly, and the adjustment is simple. Compared with the laser pulse with adjustable pulse interval obtained by the pulse train Q-switching technology, the present application is obviously better.

[0040] The sequence pulse laser is configured to enter the optical parametric oscillator 200 to change the wavelength. The frequency doubling and light splitting unit is configured in the optical path composed of the fiber laser 100, the solid-state amplifier and the optical parametric oscillator 200, and can adjust the frequency of the laser so that the 283nm (wavelength) laser required for the combustion field measurement can be output.

[0041] In one embodiment, the repetition frequency of the seed laser emitted by the fiber laser 100 is configured to be adjustable within the range of 10 to 100 kHz. That is, the pulse interval can be adjusted within the range of 10 to 100 μs. Of course, the repetition frequency of the fiber laser 100 is configured to be adjustable within the range of 100 to 10000 kHz. This application does not impose any particular restrictions on it.

[0042] Furthermore, the pulse width of the seed laser may be configured to be within the range of 1 to 50 ns. For example, in a non-limiting example, the pulse width may be within the range of 8 to 10 ns. Of course, the pulse width may also be set to a range other than 1 to 50 ns.

[0043] In one embodiment, the solid-state amplifier may be a crystal amplifier pumped by a xenon lamp. The xenon lamp discharges in a square wave, and the discharge region is amplified to output a sequence of pulses. Alternatively, the solid-state amplifier may be a crystal amplifier pumped by a diode.

[0044] Furthermore, the solid-state amplifier is configured to output a sub-pulse laser with an energy of 0.1-1J.

[0045] In one embodiment, see Figure 2 The sequential pulse optical parametric oscillator laser for combustion field measurement may also include a Faraday isolator, and at least one Faraday isolator is arranged between the optical fiber laser 100 and the solid-state amplifier.

[0046] Furthermore, the serial pulse optical parametric oscillator laser used for combustion field measurement is provided with the following in sequence: an optical fiber laser 100, a first Faraday isolator 310, a first solid-state amplifier 410, a second Faraday isolator 320, a second solid-state amplifier 420, a first frequency doubling and spectroscopic unit 510, an optical parametric oscillator 200, and a second frequency doubling and spectroscopic unit 520.

[0047] Furthermore, the second solid-state amplifier 420 is configured to output a 1064nm laser, the first frequency doubling and spectroscopic unit 510 can output a 355nm laser, the optical parametric oscillator 200 can output a 566nm laser, and the second frequency doubling and spectroscopic unit 520 can generate a 283nm laser after frequency doubling the 566nm laser.

[0048] Furthermore, the first frequency doubling and light splitting unit 510 may include a double frequency crystal and a triple frequency crystal. The 1064nm laser can be converted into a 355nm laser by passing through the double frequency crystal and the triple frequency crystal. The second frequency doubling and light splitting unit 520 may include a double frequency crystal.

[0049] Furthermore, the 355nm laser is used to pump the optical parametric oscillator 200, and the optical parametric oscillator 200 generates 400-700nm lasers, and the 566nm laser can pass through the doubled frequency crystal of the second frequency doubling and splitting unit 520 to obtain 283nm lasers.

[0050] One solution known to the inventor is to pump a dye laser with a 532nm sequence pulse, and then double the frequency to produce a 283nm laser. This solution has high conversion efficiency and narrow line width, but the disadvantage is that the dye is toxic and requires frequent dye replacement and wavelength alignment adjustment, which is troublesome to maintain and use. The method provided in the present application of a sequence pulse 355nm laser pumping an optical parametric oscillator 200 and then double the frequency to obtain a 283nm laser avoids this disadvantage.

[0051] The frequency doubling crystal and the crystal in the optical parametric oscillator 200 in the present application may be LBO (lithium triborate), BBO (β-barium borate) and other crystals, and the present application does not limit the specific materials.

[0052] The above is a preferred embodiment of the present application. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A sequential pulse optical parametric oscillator laser for combustion field measurement, characterized in that: include: A fiber laser (100) for continuously outputting pulsed laser light as a seed laser, wherein the repetition frequency of the seed laser light can be controlled and adjusted; a solid-state amplifier, wherein the seed laser is configured to enter the solid-state amplifier, and the solid-state amplifier is capable of outputting a sequence of pulsed lasers; An optical parametric oscillator (200), wherein the sequence pulse laser is configured to enter the optical parametric oscillator (200) to change the wavelength; A frequency doubling and splitting unit is arranged in an optical path formed by the optical fiber laser (100), the solid-state amplifier and the optical parametric oscillator (200), and can adjust the frequency of the laser so that a 283 nm laser can be output eventually.

2. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The sequential pulse optical parametric oscillation laser for combustion field measurement further comprises a Faraday isolator, at least one of which is arranged between the optical fiber laser (100) and the solid-state amplifier.

3. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1 or 2, characterized in that: The sequential pulse optical parametric oscillator laser for combustion field measurement is provided with the following components in the order of light propagation path: the optical fiber laser (100), a first Faraday isolator (310), a first solid amplifier (410), a second Faraday isolator (320), a second solid amplifier (420), a first frequency doubling and light splitting unit (510), the optical parametric oscillator (200), and a second frequency doubling and light splitting unit (520).

4. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 3, characterized in that: The second solid-state amplifier (420) is configured to output 1064nm laser light, the first frequency doubling and light splitting unit (510) can output 355nm laser light, the optical parametric oscillator (200) can output laser light including 566nm laser light, and the second frequency doubling and light splitting unit (520) can generate the 283nm laser light after frequency doubling the 566nm laser light.

5. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The solid-state amplifier is a xenon lamp-pumped crystal amplifier.

6. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The solid-state amplifier is a diode-pumped crystal amplifier.

7. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The repetition frequency of the seed laser is configured to be adjustable within a range of 10 to 100 kHz.

8. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The repetition frequency of the seed laser is configured to be adjustable within a range of 100 to 10,000 kHz.

9. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The pulse width of the seed laser is configured to be within a range of 1 to 50 ns.

10. The sequential pulse optical parametric oscillation laser for combustion field measurement according to claim 1, characterized in that: The solid-state amplifier is configured to output the sequence of pulsed lasers with an energy of 0.1-1J.

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