Hollow fiber compressor optimized for DUV pulses

To optimize the hollow fiber technique for DUV operation, the above discussed issues of laser-matter interaction in the UV have to be properly addressed:

	high photoionization		low intensity		lagre fiber diameter
	low losses		long fiber (large interaction length)		large spectral broadening

	long focusing geometry (f #≈1000) for beam launching		folded telescopic focusing
	high nonlinear absorption		entire focusing placed in vacuum
	small critical power of self-focusing		only He and Ne as nonlinear medium, pressure gradient

Hollow fiber setup optimized for UV operation

The key element of the UV hollow fiber arrangement is the high-transmission, long hollow-core fiber. We use a recently developed hollow fiber assembly with superior performance which incorporates stretched flexible hollow fiber.
We demonstrated the generation of ultrashort DUV pulses by applying the UV-optimized hollow fiber setup to amplified pulses of a Ti:Sapphire – KrF excimer hybrid laser system. High-energy 110-fs pulses at 248 nm were spectrally broadened by self-phase modulation in a neon-filled hollow fiber and subsequently compressed by a grating-pair. In this way, 24-fs pulses with an energy of 200 μJ were generated at 248 nm (see below). This energy is an order of magnitude higher than all previously reported values for ultra short (< 50 fs) DUV pulses.

Further information:
          T. Nagy, P. Simon:
          Generation of 200-μJ, sub-25-fs deep-UV pulses using a noble-gas-filled hollow fiber
          Opt. Lett. 34, 2300 (2009)