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Terahertz heterodyne imaging with InGaAs-based bow-tie diodes

: Minkevicius, L.; Tamosiunas, V.; Kasalynas, I.; Seliuta, D.; Valusis, G.; Boppel, S.; Roskos, H.G.; Köhler, K.


Applied Physics Letters 99 (2011), Nr.13, Art. 131101, 3 S.
ISSN: 0003-6951 (Print)
ISSN: 1077-3118
Fraunhofer IAF ()

Room-temperature detection and imaging in transmission and reflection geometries at 0.591 THz with planar asymmetrically shaped InGaAs diodes (also called bow-tie diodes) are demonstrated in direct and heterodyne mode. The sensitivity of the diodes is found to be 6 V/W in direct mode, and the noise-equivalent power (NEP) in direct and heterodyne mode is estimated to be about 4nW / (Wurzel aus Hz) and 230 fW/Hz for a local-oscillator power of 11 µW, respectively. The improvement of the dynamic range by heterodyning over direct power detection amounts to about 20 dB using pixel read-out times relevant to real-time imaging conditions.