Frequency-multiplication crystal coupler for improving output efficiency of short-wave deep ultraviolet laser

Abstract

The invention relates to a frequency-multiplication crystal coupler for improving the output efficiency of short-wave deep ultraviolet laser. The frequency-multiplication crystal coupler includes a first BaF2 crystal prism, a KBBF crystal and a second BaF2 crystal prism; the KBBF crystal is flat plate-shaped; the two BaF2 crystal prisms are respectively arranged at two side surfaces of the KBBF crystal; the top angles and bottom angles of the two BaF2 crystal prisms are adjacent to each other in pairs; the two BaF2 crystal prisms contact with optical cement at the two side surfaces of the KBBF crystal; the c-axis crystal orientation of the KBBF crystal is vertical to the contact surfaces of the two BaF2 crystal prisms and the KBBF crystal; the contact surfaces of the two BaF2 crystal prisms and the KBBF crystal, the two side surfaces of the KBBF crystal, a light beam entering surface and a light beam exiting surface are polished surfaces; light transmission directions are the crystal orientations of the two BaF2 crystal prisms, the intrinsic birefringence indexes of the two BaF2 crystal prisms in the crystal orientations being zero. With the frequency-multiplication crystal coupler adopted, reflection loss of the contact surfaces of the KBBF crystal and the BaF2 crystal prisms can be effectively decreased, and therefore, the conversion efficiency and output power of frequency-multiplied light can be improved.

Description

technical field [0001] The invention relates to the technical field of optical crystal coupling devices. More specifically, it relates to a frequency doubling crystal coupler for improving the output efficiency of short-wave deep ultraviolet laser. Background technique [0002] In the prior art, one of the most effective ways to produce ultraviolet and deep ultraviolet lasers is realized by the laser frequency conversion (including frequency doubling, sum frequency, optical parametric oscillation and amplification) technology of nonlinear optical crystals, and frequency doubling is due to the simple operation It is better than sum-frequency and other methods, and has the most practical value. The commonly used method is to cut the nonlinear optical crystal according to the phase matching angle, the fundamental frequency laser is incident at a certain angle, and the crystal is precisely rotated to adjust the incident angle to the phase matching angle (called angle tuning) or...

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Problems solved by technology

[0007] Another problem encountered when using the aforementioned patented technology (ZL01115313.X) to realize short-wave deep ultraviolet output is that the CaF 2 The crystal has intrinsic birefringence (Phys.Rev.B64, 241102), such as at 165.7nm, the refractive index n=-8.3x10 -7 , when any cut CaF 2 After the prism is made into a coupling device, the polarization direction of the 165.7nm laser will be deflected by a maximum of 18° after transmitting 1cm in it, resulting in phase mismatch, resulting in a decrease in output efficiency

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