Yuichi Asakawa

Generation of 5-W deep-UV continuous-wave radiation at 266 nm by an external cavity with a CsLiB6O10 crystal.

A Brewster-cut CsLiB6O10 crystal is employed as an external resonant frequency doubler to generate cw deep-UV radiation at 266 nm. We have generated 5.0 W of usable cw output power, which is 6.1 W in the crystal, for an incident green power of 9.6 W, corresponding to an internal conversion efficiency of 61.8%. The power obtained is, to our knowledge, three times higher than previously reported for cw 266-nm generation.

Efficient frequency doubling of 1-W continuous-wave Ti:sapphire laser with a robust high-finesse external cavity.

We demonstrated an intrinsic conversion efficiency of 56% from the input fundamental power to the generated second-harmonic power. The second-harmonic power of 581 mW was obtained from the external cavity with a LiB3O5 crystal through the frequency doubling of a 1.17-W Ti:sapphire laser at 746 nm, when the finesse of the robust external cavity was 260.

High-power CW deep-UV coherent light sources around 200 nm based on external resonant sum-frequency mixing

We report pure continuous-wave (CW) high-power (>100 mW) deep-ultraviolet (DUV) light sources emitting around 200-nm spectral region based on singly resonant sum-frequency mixing (SRSFM). Efficient DUV generation is made possible by use of a Brewster-cut CsLiB/sub 6/O/sub 10/ (CLBO) crystal near noncritically phase-matched (NCPM) condition for the SFM of 1-/spl mu/m output of neodymium lasers. The CW radiation of fifth-harmonic wavelength of a neodymium laser at 213 nm was generated by the SFM of enhanced 1064-nm radiation with single-passing 266-nm radiation produced by external-resonant frequency doubling of a 532-nm green laser. With 1.8 W of 266-nm radiation incident upon a CLBO crystal, as much as 180 mW of CW 213-nm power has been produced. The sub-200-nm CW radiation with 140-mW power has also been achieved by SFM of 1064 nm with 244-nm radiation from a frequency-doubled Argon-ion laser in the CLBO crystal operated near the NCPM condition.

Generation of all-solid-state, high-power continuous-wave 213-nm light based on sum-frequency mixing in CsLiB6O10.

Achievement of more than 100 mW of pure continuous-wave deep-ultraviolet radiation at 213 nm has been demonstrated in an efficient all-solid-state laser system that uses two Brewster-cut CsLiB6O10 (CLBO) crystals. The first crystal is used for 266-nm generation by external resonant doubling of 532-nm radiation from a frequency-doubled Nd:YVO4 laser. Subsequent sum-frequency mixing is performed in a second CLBO crystal placed in a diode-pumped Nd:YAG laser cavity to mix the single-pass 266-nm output with circulating 1064-nm light.

50% frequency doubling efficiency of 1.2-W cw Ti:sapphire laser at 746 nm

We report 50% frequency doubling efficiency of a 1.2-W continuous wave, single-mode Ti:sapphire laser at 746 nm with a LBO crystal placed in an external cavity. Theoretical analysis indicates that the linear loss of the cavity is extremely low and the mode matching efficiency is high enough to obtain a sufficient enhancement factor. In order to comprehend the coupling of the cavity, we find the relation between the input power causing the nonlinear loss and the input coupling. By using high reflectivity of 98.7% at a maximum input power, the coupling can be realized in nearly optimal condition, where 580 mW of output power has been obtained.

High-power CW DUV coherent light source around 200 nm

An efficient optical frequency mixer employing a Brewster-cut CLBO crystal has been developed for the generation of high-power CW DUV coherent radiation. DUV light of 180mW at 213nm and 140mW at 198.5nm have been produced.

Toward nano-process applications with laser-cooled silicon atoms

We have developed an all-solid-state 252nm coherent light source for laser cooling of silicon atoms with tow-stage highly efficient frequency conversions with external cavities. With the coherent light source, it is possible to manipulate the atomic motion of the silicon atoms towards nano-process applications. In this paper, deflection, collimation, and axial velocity selection of the silicon atomic beam with the coherent light source are discussed.

High power CW DUV coherent light sources for metrology applications

Continuous wave coherent light sources have been developed primarily intended for metrology tools in advanced semiconductor manufacturing. 5 W at 266 nm, 150 mW at 213 nm, and 120 mW at 198.5 nm have been respectively generated.

A high finesse external cavity with a LiB/sub 3/O/sub 5/ crystal for efficient frequency doubling of CW Ti:sapphire laser

We have demonstrated highly efficient frequency doubling with a high finesse external cavity. We obtained 581-mW as the second harmonic output power by frequency doubling of 1.17 W, 746 nm Ti:sapphire laser. The conversion efficiency for generated power inside the cavity was 56% and the cavity finesse was 260. The output power was very stable with a power fluctuation of less than 2% for a second when the standard deviation was 7.4 /spl times/ 10/sup -3/.

Highly efficient tunable single-frequency cw deep ultraviolet coherent light source toward laser cooling of silicon atoms

Summary form only given. We developed a highly efficient tunable cw single-frequency light source in the deep ultraviolet region for laser cooling of silicon atoms. In the system two-stage highly efficient frequency conversion with binary external cavities is employed. The first frequency conversion system consists of a bow-tie ring type cavity and the phase matched LBO crystal, producing the second harmonic power of 526 mW at 373 nm by frequency doubling of the fundamental (746 nm) of a Ti:sapphire laser with a power of 1.3 W. The conversion efficiency in the first cavity reaches 38.4%, which is in good agreement with our numerical calculation. In the second stage, the system consists of a doubly resonant bow-tie-type cavity and the phase matched BBO crystal, generating the 252-nm radiation successfully, by the sum frequency mixing between the obtained 373-nm radiation with a power of 480 mW and the 780-nm light from a tunable laser diode with a power of 380 mW. The frequency of the single-frequency-laser diode is locked to the cavity frequency stabilized to the frequency of the second harmonic of the single-frequency Ti:sapphire laser through the two-stage Hansch-Couillaud stabilization scheme. The performance characteristics of this system should be enough to achieve laser cooling of silicon atoms.