Production of pairs of synchronized pulses by optical parametric generation and oscillation using aperiodically poled lithium niobate.

Abstract

We report two sources of synchronized pairs of pulses based on optical parametric generation (OPG) and oscillation (OPO) that use aperiodically poled lithium niobate (APLN) as the nonlinear medium. The main purpose of these sources is to obtain terahertz radiation through difference-frequency generation. The APLN crystal was designed to generate two signals with their corresponding idlers from a single pump pulse; the signal wavelengths are around 1450nm, and the frequency difference between them is tunable between ∼1 and 10THz. In the OPO configuration, pumped by a Q-switched Nd:YAG laser (12ns FWHM, 13mJ), we obtain pairs of synchronized signals (∼5 ns FWHM) with a combined energy of 740μJ; each signal has a bandwidth of <105 GHz. In the OPG configuration, we use a Q-switched Nd:YLF laser that emits shorter pulses (1.6ns FWHM, 350μJ), obtaining synchronized signal pulses with a combined energy of 38 μJ; each signal has a pulse width of 0.8ns and a bandwidth of <175 GHz. The advantages of these sources for difference frequency generation are discussed.