Quasi-optical highly sensitive Schottky-barrier detector for a wide-band FIR FEL

A wide-band FIR detector based on the Schottky-barrier diode for the use on a far-infrared FEL facility has been developed. The detector consists of a GaAs chip with diodes of sub-micrometer diameters and a traveling-wave antenna in a 90° corner-cube reflector that provided effective transmission of the FIR power to the diode from the input FIR focusing lens. The antenna has been optimized for a wavelength of 337 μm. At this wavelength, the detector has a sensitivity of 200 V/W and a noise equivalent power (NEP) of 0.1 nW/Hz1/2. These measurements were made by a HCN laser. For a radiation wavelength of 119 μm (H2O laser) the sensitivity and NEP values were measured to be 20 V/W and 1.0 nW/Hz1/2, respectively. The results of measurements from the compact wide-band FIR FEL facility by the detector in a wide wavelength range are presented. The potentialities of the detector are investigated.