Enhanced coherent terahertz emission from indium arsenide

We present results showing enhancement of terahertz (THZ) emission from ind ium arsenide (InAs) which demonstrate that at 170 K and magnetic fields (B) up to B = 8 T, increased visible to terahertz conversion efficiencies are possible. With an average total power of 1 mu W at B = 0 T and 12 mu W at B = 8 T, we have observed an order of magnitude increase in total conversion efficiency with no visible saturation. The InAs sample was placed within a n optical cryostat and illuminated by Ti: Sapphire laser pulses with durati on 100 fs. The terahertz powers were recorded using a calibrated He-cooled bolometer. Free space electro-optic sampling (EOS) measurements confirmed t he coherent nature of this radiation over the field and temperature range i nvestigated. The optical cryostat could produce magnetic fields of B = 8 T at temperatures from 3 to 300 K. We therefore present a comprehensive study of the terahertz generation as a function of both these variables and a br ief comparison with an alternative material system, InSb.