Terahertz Local Oscillator Via Difference Frequency Generation in III-V Semiconductors Using Frequency Stabilized Lasers

摘要

Terahertz (THz) heterodyne receiver systems are required by NASA to monitor gas concentrations related to the Earth's ozone depletion. To this end, NASA needs compact, solid state, tunable THz local oscillators. THz LOs have been developed using three means: 1) All-electronic LOs using mixers in combination with Gunn oscillators, 2) Hybrid Photo-electronic LOs using a cw analog of the Auston switch, and 3) All-photonic THz LOs using coherent sources, such as vapor lasers or solid-state Quantum Cascade Lasers, and down converting lasers using nonlinear crystals. In this dissertation, we began with two frequency stabilized Nd:YAG lasers, locked to a common reference cavity, as a starting point to having a stable input into a nonlinear optical frequency conversion system. Following this, we explored the nonlinear crystals useful for THz generation, and the phasematching schemes that could be employed by each. We concluded by settling on highly insulating III-V semiconductor crystals as the proper choice of nonlinear element, and put together a new phasematching method that is most useful for them.