Abstract
Ultrabroadband optical parametric generation in the near-IR (approximately 135 THz, 1.15-2.4 microm) is demonstrated using bismuth triborate, BiB(3)O(6) (BIBO), in a collinear geometry. The white light continuum energy obtained with a single stage reached 15 microJ (internal conversion efficiency of approximately 7%). Integral pulse durations as short as 63 fs were derived from the recorded FROG traces, comparable to the 45 fs pulse duration of the 1 kHz Ti:sapphire regenerative amplifier used for pumping at 800 nm.
Highlights
The availability of ultrabroadband coherent radiation in the near-IR in combination with femtosecond pulse durations could find numerous applications in various fields such as timeresolved broadband spectroscopy, spectral comb generation for metrology or high-harmonic generation
It should be noted that such white-light continuum (WLC) generation in transparent materials using a single filament [3] could find some direct applications as a source of broadband coherent radiation, typical energies produced by such schemes operating at 1 kHz are very low, of the order of 10s of nJ
When collinear e→oo interaction in the x-z plane of the monoclinic BIBO is used, the group velocity mismatch (GVM) between the signal and idler waves vanishes near degeneracy but, especially for pump wavelengths near 800 nm, this is accompanied by vanishing group velocity dispersion (GVD) of the signal and idler
Summary
The availability of ultrabroadband coherent radiation in the near-IR in combination with femtosecond pulse durations could find numerous applications in various fields such as timeresolved broadband spectroscopy, spectral comb generation for metrology or high-harmonic generation. With the invention of the Ti:sapphire based femtosecond amplifiers operating near 800 nm at repetition rates of the order of 1 kHz and the crystals of the borate family, e.g. β-BaB2O4 (BBO) and LiB3O5 (LBO), combining high nonlinearity and damage threshold, several parametric schemes for efficient generation of femtosecond pulses in the near-IR were developed in the beginning of the 1990’s. Their first stage was based either on amplification of the parametric superfluorescence (optical parametric generator, OPG) or the amplification of white-light continuum (WLC), (optical parametric amplifier, OPA) [1,2]. In the present work we investigate a much simpler collinear OPG scheme based on a single stage of BIBO pumped near 800 nm, which produces output energies on the 10 μJ level with comparable bandwidth and shorter integral pulse duration
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