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Proceedings Paper

Development of high coherence, 200mW, 193nm solid-state laser at 6 kHz
Author(s): T. Nakazato; M. Tsuboi; T. Onose; Y. Tanaka; N. Sarukura; S. Ito; K. Kakizaki; S. Watanabe
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Paper Abstract

The high coherent, high power 193-nm ArF lasers are useful for interference lithography and microprosessing applications. In order to achieve high coherence ArF lasers, we have been developing a high coherence 193 nm solid state laser for the seeding to a high power ArF laser. We used the sum frequency mixing of the fourth harmonic (FH) of a 904-nm Ti:sapphire laser with a Nd:YVO4 laser (1342 nm) to generate 193-nm light. The laser system consists of a single-mode Ti:sapphire oscillator seeded by a 904-nm external cavity laser diode, a Pockels cell, a 6-pass amplifier, a 4-pass amplifier, a 2-pass amplifier and a wavelength conversion stage. The required repetition rate of 6 kHz corresponding to the ArF laser, along with a low gain at 904 nm induces serious thermal lens effects; extremely short focal lengths of the order of cm and bi-foci in the vertical and horizontal directions. From the analysis of thermal lens depending on pump intensity, we successfully compensated the thermal lens by dividing a 527-nm pump power with 15, 25 and 28 W to 3-stage amplifiers with even passes, resulting in the output power above 10W with a nearly diffraction limited beam. This 904-nm output was converted to 3.8 W in the second harmonic by LBO, 0.5 W in FH by BBO sequentially. Finally the output power of 230 mW was obtained at 193 nm by mixing the FH with a 1342-nm light in CLBO.

Paper Details

Date Published: 20 February 2015
PDF: 14 pages
Proc. SPIE 9342, Solid State Lasers XXIV: Technology and Devices, 93420P (20 February 2015); doi: 10.1117/12.2078601
Show Author Affiliations
T. Nakazato, Tokyo Univ. of Science (Japan)
M. Tsuboi, Tokyo Univ. of Science (Japan)
Osaka Univ. (Japan)
T. Onose, Gigaphoton Inc. (Japan)
Y. Tanaka, Tokyo Univ. of Science (Japan)
N. Sarukura, Osaka Univ. (Japan)
S. Ito, Gigaphoton Inc. (Japan)
K. Kakizaki, Gigaphoton Inc. (Japan)
S. Watanabe, Tokyo Univ. of Science (Japan)

Published in SPIE Proceedings Vol. 9342:
Solid State Lasers XXIV: Technology and Devices
W. Andrew Clarkson; Ramesh K. Shori, Editor(s)

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