L-Histidine Tetrafluoroborate: A New Solution-Grown Frequency Conversion Crystal for Parametric Processes from 300-1300 nm

L-histidine tetrafluoroborate (HFB) is a new nonlinear optical material, potentially useful for UV to near IR frequency conversion applications. HFB is an example of a semiorganic material, in which a highly nonlinear organic anion is incorporated into an inorganic salt matrix. HFB grows readily from solution, displays favorable mechanical characteristics for nonlinear optical applications, and has adequate birefringence to allow phase matched parametric processes over much of its transparency range (250 nm to 1300 nm). Its crystal structure, refractive indices, and phase matching conditions are reported. The phase matching locus and angular sensitivity for second harmonic generation of 1064 nm light in single crystals of HFB were measured. For 1.064 μm second harmonic generation, the effective non-linearity for HFB is comparable to that of beta barium borate (~ 2 pm/V), while its angular sensitivity [δ(Δk)/δθ] is somewhat smaller.