High-average-power light source below 200 nm from a KBe(2)BO(3)F(2) prism-coupled device

Phase-matched frequency conversion below 150 nm in KBe2BO3F2

Sum frequency mixing has been demonstrated below 150 nm in KBeBO₃F₂ by using the fundamental with its fourth harmonic of a 6 kHz Ti: sapphire laser system. The wavelength of 149.8 nm is the shortest ever obtained to our knowledge by phase matching in nonlinear crystals. The output powers were 3.6 μW at 149.8 nm and 110 μW at 154.0 nm, respectively. The phase matching angles measured from 149.8 to 158.1 nm are larger by 3-4 degrees than those expected from the existing Sellmeier equation. The measured transmission spectra of KBeBO₃F₂ crystals support the generation of coherent radiation below 150 nm.

Single-mode deep-UV light source at 191.7 nm by seventh-harmonic generation of a high-power, Q-switched, injection-locked 1342 nm Nd:YVO₄ laser

A single-mode deep-UV laser at 191.7 nm is demonstrated by seventh-harmonic generation of a single-mode 1342 nm Nd:YVO₄ laser. The fundamental laser is an injection-locked, Q-switched ring laser at 10 kHz pulse repetition frequency. By cascaded second-harmonic and sum-frequency generation, an average power of 230 mW at 191.7 nm is achieved. At 185 mW, the setup features a Gaussian beam with a beam quality factor of M²<1.5. A pulse duration of 9 ns with pulse energy fluctuations of σ<3% is obtained. The long-term spectral width is approximately 240 MHz full width at half-maximum, measured with a homemade scanning confocal Fabry-Perot interferometer. This work opens possibilities in fiber Bragg grating production, allowing the inscription of long gratings.

All solid-state 191.7 nm deep-UV light source by seventh harmonic generation of an 888 nm pumped, Q-switched 1342 nm Nd:YVO₄ laser with excellent beam quality

In this paper we report on the realization of a deep-UV light source using the 1.3 μm transition of neodymium as pumping wavelength. The 191.7 nm radiation was obtained by generating the seventh harmonic of a high-power Q-switched 1342 nm Nd:YVO4 laser. A cesium lithium borate crystal was used for sum frequency mixing of the sixth harmonic and the fundamental. With a total of four conversion stages, up to 240 mW were achieved, with excellent beam quality at 155 mW (M2 < 1.7) and 190 mW (M2 < 1.9).

Generation of quasi-continuous-wave vacuum-ultraviolet coherent light by fourth-harmonic of a Ti:sapphire laser with KBBF crystal

We report the generation of quasi-continuous-wave vacuum-ultraviolet (VUV) coherent light based on a Ti:sapphire laser with two successive frequency doubling stages. In the first stage, UV light at 399 nm with power of 1.1 W was obtained by exploiting an enhanced cavity. With a KBBF crystal as nonlinear material, quasi-continuous-wave VUV coherent light with power of about 25 mW at 199.5 nm and 4.7 mW at 193.5 nm were achieved through a single-pass SHG configuration, respectively, in the second stage.

Watt-level tunable deep ultraviolet light source by a KBBF prism-coupled device

We have obtained an average output power as much as 1.2 W at 200 nm by using a 2.71-mm thick KBe2BO3F2 crystal optically contacted by CaF2 and SiO2 prisms on the both sides. Watt-level average-power was generated tunably in the deep ultraviolet region from 185 nm to 200 nm. The average power is the highest, to our knowledge, ever obtained by nonlinear crystals in the wavelength region below 200 nm.

Widely tunable and high-average-power fourth-harmonic generation of a Ti:sapphire laser with a KBe2BO3F2 prism-coupled device

Using a KBe(2)BO(3)F(2) prism-coupled device, we have realized the high-average-power output in the wide range from 170 to 232.5 nm by second-harmonic generation of a frequency-doubled Ti:sapphire laser. The output power in the UV from 175 to 232.5 nm exceeds 2 mW, the highest power being 119.8 mW at 202.5 nm. Moreover, tunable output powers above 100 mW have also been obtained for deep-UV light from 193.5 to 200 nm.