Generation and Photonic Guidance of Multi-Octave Optical-Frequency Combs
F. Couny,1
F. Benabid,1*
P. J. Roberts,2
P. S. Light,1
M. G. Raymer3
Ultrabroad coherent comb-like optical spectra spanning several octaves are a chief ingredient in the emerging field of attoscience. We demonstrate generation and guidance of a three-octave spectral comb, spanning wavelengths from 325 to 2300 nanometers, in a hydrogen-filled hollow-core photonic crystal fiber. The waveguidance results not from a photonic band gap but from the inhibited coupling between the core and cladding modes. The spectrum consists of up to 45 high-order Stokes and anti-Stokes lines and is generated by driving the confined gas with a single, moderately powerful (10-kilowatt) infrared laser, producing 12-nanosecond-duration pulses. This represents a reduction by six orders of magnitude in the required laser powers over previous equivalent techniques and opens up a robust and much simplified route to synthesizing attosecond pulses.
1 Department of Physics, Centre for Photonics and Photonic Materials, University of Bath, Bath BA2 7AY, UK.
2 Communications, Optics and Materials, Technical University of Denmark, Lyngby, DK-2800, Denmark.
3 Oregon Center for Optics and Department of Physics, University of Oregon, Eugene, OR 97403, USA.
* To whom correspondence should be addressed. E-mail: f.benabid{at}bath.ac.uk
