Solid-state seeded nano-second pulse CO2 oscillator for extreme ultraviolet lithography

Krzysztof M Nowak


This Letter describes in some detail a novel, solid-state seeded, nano-second pulse, multi-line CO2 oscillator designed and built for the extreme ultraviolet (EUV) laser-produced-plasma (LPP) source. The oscillator employed quantum cascade laser (QCL) seeders, a spectral beam combiner and a diffusion-cooled, radio-frequency-discharge excited, slab-waveguide CO2 amplifier in a multi-pass and compact regenerative amplifier configuration. The output spectrum consisted of individually controlled laser lines of 0001-1000 band of a CO2 molecule, P18, P20 and P22 with a target 4-line operation (P18-P24). The resistance to self-seeding of more than 40dB and to the parasitic back-seeding of more than 55dB was realized. The oscillator produced up to 20W of average output power at repetition rate of 100kHz in a near-diffraction limited beam of M2 lower than 1.3 and RMS pointing stability below 50 microradians.

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Photonics Letters of Poland - A Publication of the Photonics Society of Poland
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ISSN: 2080-2242