Ultrabroad-band phase matching in two recently grown nonlinear optical crystals for the generation of tunable ultrafast laser radiation by type-I noncollinear optical parametric amplification

Abstract

It was found that the generation of ultrabroad-band femtosecond pulsed laser radiation is possible in two recently grown nonlinear optical crystals, K2Al2B2O7 (KABO) and CsLiB6O10 (CLBO), by employing a type-I noncollinear optical parametric amplification (NOPA) scheme, pumped by Ti:sapphire second harmonic (395 nm) radiation. The phase-matching bandwidths of the process are as large as 152 and 164 THz in KABO and CLBO crystals, with the values of the noncollinear angles (α) between pump input (considered monochromatic) and seed pulses input are 3.3° and 3.0°, respectively. The phase-matching bandwidth calculated for the same type-I NOPA in BBO crystal is 157 THz with α=3.7°. In addition to the large phase-matching bandwidth in CLBO, the major advantages of this crystal are that it can easily be grown to large sizes and it also has a higher threshold against laser damage. The most attractive properties of KABO crystal are that it is nonhygroscopic as well as mechanically robust and easy to cut and polish. Having moderate birefringence the angular and spectral bandwidths of both CLBO and KABO crystals are larger than that of BBO crystal and the deleterious walk-off angles are smaller than that of BBO. The walk-off angles at the pump wavelength of NOPA with CLBO, KABO, and BBO crystals are about 2.1°, 2.7°, and 4.0°, respectively. Here we present the nonlinear optical parametric properties of CLBO and KABO crystals for the generation of ultrabroad band femtosecond laser radiation by the NOPA technique, since we know of no such report so far in the literature.