CN87214068U - Miniature internal chamber raman frequency-shift laser - Google Patents

Abstract

The utility model belongs to a miniature internal chamber Raman frequency-shift laser which is particularly suitable for miniature hand-held distance-measuring instruments which are safe to human eyes. A miniature Q-switching YAG is used as a laser pumping; a Raman tube which is sealed with high-pressure methane gas is arranged in a pump light resonant cavity; both one window piece of the Raman tube and one reflector of the resonant cavity are plane-convex lenses. The utility model has the advantages of less energy input, low Raman scattering threshold and high energy conversion efficiency.

Description

Miniature internal chamber Raman frequency-shift laser

The utility model belongs to tunable laser, particularly belongs to small-sized laser pumping and gas Raman medium and places the interior shift frequency laser of a resonant cavity together.

Carrying out stimulated Raman scattering nonlinear optics shift frequency in gas medium is a kind of highly effective means of carrying out frequency inverted at light-wave band.In actual applications in order to reduce the oscillation threshold of excited Raman, improve energy conversion efficiency, the structure of Raman shift frequency laser diode and the influence of other factors have been carried out a large amount of research both at home and abroad, people propose the Raman pond is placed on formation inner chamber double wave-length vibration device in the pump laser cavity for this reason.United States Patent (USP) (4,327,337) be entitled as the structure that " the Raman shift frequency in the superpower laser chamber " (Intracavity Raman Fre-quency Conve rsion in A High Power Laser) announced a kind of inner chamber Raman shift frequency laser, as shown in Figure 1: Raman pond (6) place in the resonant cavity of speculum (1) and (3) composition with laser medium (4), speculum (1) is to pump light wavelength total reflection diaphragm, speculum (3) is high anti-to the pump light wavelength, to excited Raman optical wavelength part transmission diaphragm.It is high anti-to the Raman light wavelength to insert an eyeglass (2) in resonant cavity between laser medium and the Raman pond, and high saturating to the pump light wavelength, eyeglass (2) and (3) constitute the vibration chamber to Raman light.Q-switch places between eyeglass (1) and (2), is filled with the gas Raman medium in the Raman pond, and two ends are by window (7), (8) sealing.It is still very high that this kind structure produces the Raman oscillation threshold, only is applicable to the high power laser of average output power more than 10W, needs with large-sized laser medium and stronger input electric power.The inner chamber Raman frequency shifter of another kind of structure of resonant cavity has been reported in U.S. AD report 7127609, exercise question be " is the stimulated Raman scattering of pumping in methane with Nd:YAG " (Stimulated Raman Scattering in Methane With Nd:YAG Pump) as shown in Figure 2, two ends envelopes has plane window (7) (8), in fill methane gas Raman pond ［ 6 ］ place the Nd:YAG ［ 4 ］ that forms by speculum ［ 1 ］ and ［ 3 ］ to vibrate in the chamber.Different with above-mentioned United States Patent (USP) is to be added with a pair of convex lens at two ends, Raman pond ［ 6 ］ pump beam is focused in the Raman pond to improve optical intensity density, the reduction threshold value.The polarizer ［ 11 ］ and electric-optically Q-switched crystal ［ 5 ］ place between speculum ［ 1 ］ and the convex lens ［ 9 ］, but do not have in the chamber shown in Figure 1 to the high anti-eyeglass ［ 2 ］ of Raman light, so eyeglass ［ 1 ］ and ［ 3 ］ locate all to have the Raman light of 1.54 μ m to export.Therefore this structure still is not suitable for the small-sized Raman shift frequency laser of low electric power input.

The utility model improves the structure of resonant cavity of above-mentioned inner chamber Raman shift frequency laser, for further improving the conversion efficiency of stimulated Raman scattering, reduce the stimulated Raman scattering threshold value, so that make the miniaturization of Raman shift frequency laser, practicability, particularly being applicable to needs small portable, can produce again in the small-power hand-held laser rangefinder to the eye-safe light beam.

The utility model has designed a kind of new construction of small-sized inner chamber Raman shift frequency laser diode, it comprises the optical cavity of being made up of a speculum and a planoconvex spotlight, they are carried out the optics adjustment, making its optical alignment, coaxial, speculum is the completely reflecting mirror to the pumping laser wavelength, the plane of planoconvex spotlight is coated with the pumping laser wavelength high anti-outside the chamber, to the high saturating media coating of Raman light wavelength, convex surface is coated with pump light and Raman light dual wavelength anti-reflection film in the chamber.Between two mirrors, placing Q-switch, laser pumping medium and be filled with the Raman pond of gases at high pressure along optical axis.It is coaxial that they carry out optical alignment mutually.The Raman pond is near an end Feng Youyi piece planoconvex spotlight of laser medium, its plane is coated with the Raman light wavelength high anti-outside the Raman pond, to the high saturating media coating of pump light wavelength, convex surface has the dual wavelength anti-reflection film in the Raman pond, the anti-reflection plane of other end Feng Youyi dual wavelength, Raman pond window.

This kind new construction that the utility model adopts is compared with the structure that above-mentioned prior art is described, because it adopts the speculum ［ 3 ］ among planoconvex spotlight replacement prior art Fig. 1, Fig. 2, make it not only have reflex also to have focussing force concurrently to laser pumping light, adopt another piece planoconvex spotlight to replace speculum ［ 2 ］, lens ［ 9 ］ and Raman pond window ［ 7 ］ among prior art Fig. 1, Fig. 2, planoconvex spotlight of its usefulness just can be had concurrently Raman light feedback, two light are focused on and Raman pond (interior dress gases at high pressure) is sealed three kinds of functions.Adopt this structure of the present utility model, not only improve optical intensity density but also reduced the loss of optical element and optical interface thereof, make compact conformation, therefore be that a kind of to have the Raman scattering threshold value low, input electric power is little, and obtains the small utility inner chamber Raman shift frequency laser of high energy conversion efficiency.

Below in conjunction with accompanying drawing the utility model is described in more detail.Accompanying drawing 1 is the structure of resonant cavity of existing high-power inner chamber Raman shift frequency laser.

Accompanying drawing 2 for existing be the experimental provision of the resonant cavity of the stimulated Raman scattering of pumping in methane with Nd:YAG

Accompanying drawing 3 is small-sized inner chamber Raman frequency-shift laser structure of resonant cavity.

A kind of most preferred embodiment of the present utility model is a kind of small-sized raman frequency laser that is used for hand-hold type eye-safe rangefinder, be described below with reference to Fig. 3: laser medium ［ 4 ］ adopts the YAG crystal bar, Q-switch is dye Q ［ 5 ］, dye cell ［ 5 ］ is placed between speculum ［ 1 ］ and the YAG rod ［ 4 ］, and experiment obtains its energy conversion efficiency of this placement and is higher than dye cell is placed between YAG rod and the Raman pond.Be packaged with 60～70 atmospheric methane gass in the Raman pond ［ 6 ］, for avoid in the Raman pond simultaneous another kind of non-linear process one stimulated Brillouin scattering to the chamber in the destruction of optical element, through calculating and experimental verification, the distance L 1 of speculum ［ 1 ］ and planoconvex lens ［ 13 ］ should be less than or equal to the distance L 2 between planoconvex lens ［ 13 ］ and ［ 12 ］, in this embodiment, we adopt L1 is 80mm, and L2 is 13.1mm, the focal distance f 1=f2=60mm of two planoconvex lens.Speculum ［ 1 ］ is the diaphragm to 1.06 μ m total reflections, and the plane of planoconvex spotlight ［ 13 ］ is coated with 1.54 μ m high reflectances, and to high saturating this soldier's of 1.06 μ m high strength media coating, convex surface is coated with 1.54 μ m and 1.06 μ mm dual wavelength anti-reflection films.［ 8 ］ two sides all is coated with the dual wavelength anti-reflection film in the flat window, and it is that 90～100% pairs 1.54 μ m transmitances are about 85～95% that planoconvex spotlight ［ 12 ］ level crossing has 1.06 μ m highly reflecting films reflectivity.Convex surface is coated with the dual wavelength anti-reflection film.In this kind embodiment, the YAG rod is φ 4 * 50mm, and always importing electric energy is that 2.8 joules of seals can produce greater than 1.54 burnt μ m Raman shift frequency light of 5 millis.Pulse duration is about 10ns.Is 0.18% by electric energy to total energy conversion efficiency of 1.54 μ m, the Raman pond is removed, surveyed 1.06 μ m output under this input electric energy, it is burnt that the best reaches 16.4 millis, reach 26% by 1.06 μ m to 1.54 μ m energy conversion efficiencies, photon conversion efficiency reaches 38%.If with the YAG rod of φ 5 * 70mm, electric-optically Q-switched as pumping, obtain the burnt 1.54 μ m output of 8.6～12 millis, the energy conversion efficiency from 1.06 μ m to 1.54 μ m reaches more than 30%, and photon conversion efficiency reaches 45%, and the stability of exporting 1.54 μ m is better than 5%.

Claims (5)

1, a kind of small-sized inner chamber Raman shift frequency laser, it comprises by the speculum of two optical alignments [1], [12] resonant cavity of Zu Chenging, placing gain medium [4] Q-switch [5] and sealing the Raman pond [6] that gases at high pressure are arranged along optical axis in the resonant cavity, speculum [1] is to pump light wavelength completely reflecting mirror, it is characterized in that said Raman pond [6] one end Feng Youyi convex lens [13], its plane is coated with the Raman light wavelength high anti-, to the high saturating deielectric-coating of pump light wavelength, convex surface is coated with the dual wavelength anti-reflection film, the anti-reflection window of other end Feng Youyi plane dual wavelength, said speculum [12] is a planoconvex spotlight, the plane is coated with to be reflected the high transmission medium film of Raman light wavelength the pump light wavelength is high, and convex surface is coated with the dual wavelength anti-reflection film.

2, as the said small-sized inner chamber Raman shift frequency laser of claim 1, it is characterized in that laser medium is the YAG crystal, Q switching is a dye Q, and the Raman pond is filled with high pressure methane gas.

3, the distance L that it is characterized in that speculum (1) and planoconvex lens (13) as the said small-sized inner chamber Raman shift frequency laser of claim 2 ₁Smaller or equal to the distance L of planoconvex lens (13) with planoconvex lens (12) ₂

4, as the said small-sized inner chamber Raman shift frequency laser of claim 3, it is characterized in that said Q switching (5) is positioned between speculum (1) and the laser medium (4).

5, as the said small-sized inner chamber Raman shift frequency laser of claim 1, the atmospheric pressure value that it is characterized in that said high pressure methane gas is 60～70 atmospheric pressure.

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