Terahertz Sources Based on Intracavity Parametric Down-Conversion in Quasi-Phase-Matched Gallium Arsenide


Joseph E. Schaar, Konstantin L. Vodopyanov, Paulina S. Kuo, Martin M. Fejer, Xiaojun Yu, Angie Lin, James S. Harris, David Bliss, Candace Lynch, Vladimir G. Kozlov, and Walter Hurlbut


We have efficiently generated tunable terahertz (THz) radiation using intracavity parametric down-conversion in gallium arsenide (GaAs). We used three types of microstructured GaAs to quasi-phase-match the interaction: optically contacted, orientation-patterned, and diffusion-bonded GaAs. The GaAs was placed in an optical parametric oscillator (OPO) cavity, and the THz wave was generated by difference-frequency mixing between the OPO signal and idler waves. The OPO used type-II phase- matched periodically poled lithium niobate as a gain medium and was synchronously pumped by a mode-locked laser at 1064 nm (7 ps and 200 nJ at 50 MHz). With center frequencies spanning 0.4– 3.5 THz, 250-GHz bandwidth radiation was generated. We mea- sured two orders of optical cascading generated by the mixing of optical and THz waves. In a doubly resonant oscillator (DRO) configuration, the efficiency increased by 21 × over the singly resonant oscillator performance with an optical-to-THz efficiency of 10−4 and average THz power of 1 mW. The GaAs stabilized the DRO by a thermooptic feedback mechanism that created a quasi- continuous-wave train of THz pulses.


IEEE Journal of Selected Topics in Quantum Electronics






Schaar JSTQE2008518.68 KB