Abstract

Various ultrafast electronic and optoelectronic devices have been developed as sources for the terahertz spectral region. Most of these sources exhibit relatively low power spectral density. This can be due to their inherently broadband nature, as with ultrafast switches pumped with subpicosecond optical pulses [1], or to their low conversion efficiencies, as with optical three-wave mixing [2]. Optical heterodyne conversion, or photomixing, has recently been explored as a technique for the production of coherent radiation at terahertz frequencies [3]. In order to produce useful levels of power in this frequency range a photomixer must exhibit high responsivities, be robust under optical pumping, and be capable of ultrafast operation. Low-temperature-grown (LTG) GaAs photomixers have demonstrated all of these properties and should be useful for applications such as ultra-wideband sweep oscillators and tunable local oscillators. This paper will discuss the latest LTG-GaAs photomixer devices, showing twenty times more output power at 3 THz than earlier devices [4].

© 1995 Optical Society of America