637 <b> <i>μ</i> </b>W emitted terahertz power from photoconductive antennas based on rhodium doped InGaAs
Robert B. Kohlhaas, Steffen Breuer, Lars Liebermeister, Simon Nellen, Milan Deumer, Martin Schell, M. P. Semtsiv, W. T. Masselink, Björn Globisch
Abstract
We investigate photoconductive terahertz (THz) emitters compatible with 1550 nm excitation for THz time-domain spectroscopy (TDS). The emitters are based on rhodium (Rh) doped InGaAs grown by molecular beam epitaxy. InGaAs:Rh exhibits a unique combination of ultrashort trapping time, high electron mobility, and high resistivity. THz emitters made of InGaAs:Rh feature an emitted THz power of 637 μW at 28 mW optical power and 60 kV/cm electrical bias field. In particular for a fiber coupled photoconductive emitter, this is an outstanding result. When these emitters are combined with InGaAs:Rh based receivers in a THz TDS system, 6.5 THz bandwidth and a record peak dynamic range of 111 dB can be achieved for a measurement time of 120 s.