Absolute Response and Noise Equivalent Power of Cyclotron Resonance-Assisted InSb Detectors at Submillimeter Wavelengths

Spectra are presented of the responsivity and noise equivalent power (NEP) of liquid-helium-cooled InSb detectors as a function of magnetic field in the range 20-110 cm-1. The measurements are all made using a Fourier transform spectrometer with thermal sources. The results show a discernable peak in the detector response at the conduction electron cyclotron resonance (CCR) frequency for magnetic fields as low as 3 kG. The magnitude of responsivity at the resonance peaks is roughly constant with magnetic field and is comparable to the low-frequency hot-electron bolometer response. The NEP at the peaks is found to be comparable to the best long wavelength results previously reported. For example, we measure NEP=4.5×10- 13 W/Hz1/2 at 4.2 K, 6 kG, and 40 cm-1. The InSb CCR will provide a much improved detector for laboratory spectroscopy, as compared with hot electron bolometers, in the 20-100 cm-1 range.