Optical parametric generation of high-energy femtosecond pulses in the 1-3 μm spectral range using BiB 3 O 6

Abstract

We analyze the phase-matching properties of the monoclinic nonlinear crystal BiB 3 O 6 (BIBO) for optical parametric amplification of femtosecond pulses when pumped near 800 nm by Ti:sapphire based laser systems. BIBO possesses higher figure of merit than β-BaB 2 O 4 (BBO) and extremely large parametric gain bandwidth for collinear interaction. Experimentally, we compare type-II BIBO and BBO in a double pass optical parametric amplifier (OPA), pumping by amplified 80-fs pulses near 800 nm at a repetition rate of 1 kHz. The conversion efficiency obtained with BIBO is higher and a total energy output (signal + idler) of about 80 µJ is obtained in the plateau region of the tunability curve (1-3 µm) with an uncoated sample, for a total pump energy of 375 µJ. Shorter pulse durations were obtained with BIBO: e.g. 120 fs (FWHM) near 3 µm for the idler pulses. Substantial power scaling of such a femtosecond OPA is possible using a large aperture BIBO crystal in the second stage and we demonstrate a total energy output (signal + idler) exceeding 1 mJ, corresponding to an intrinsic conversion efficiency of ≈32% for the second stage, using a specially designed highpower Ti:sapphire pump system operating at 1 kHz. The tunability extends in this case from 1.1 to 2.9 µm. The high parametric gain and broad amplification bandwidth of type-I BIBO allow the maintenance of the pump pulse duration, leading to pulse lengths less than 140 fs, both for the signal and idler pulses, even at such high output levels.

Femtosecond nonlinear frequency conversion based on BiB3O6

“…These experiments have been realized, without exception, at ICFO and MBI, and partially summarized in previous conference papers [55][56][57][58]. Several new experimental demonstrations will also be included.…”