Karasik, B. S., Lindgren, M., Zorin, M. A., Danerud, M., Winkler, D., Trifonov, V. V., et al. (1994). Picosecond detection and broadband mixing of near-infrared radiation by YBaCuO films. In M. Nahum, & J. - C. Villegier (Eds.), Proc. SPIE (Vol. 2159, pp. 68–76). Spie.
Abstract: Nonequilibrium picosecond and bolometric responses of YBCO films 500 angstroms thick patterned into 20 X 20 micrometers 2 size structure to 17 ps laser pulses and modulated radiation of GaAs and CO2 lasers have been studied. The modulation frequencies up to 10 GHz for GaAs laser and up to 1 GHz for CO2 were attained. The use of small radiation power (1 – 10 mW/cm2 for cw radiation and 10 – 100 nJ/cm2 for pulse radiation) in combination with high sensitive read-out system made possible to avoid any non-linear transient processes caused by an overheating of sample above a critical temperature or S-N switching enhanced by an intense radiation. Responses due to the change of kinetic inductance were believed to be negligible. The only signals observed were caused by a small change of the film resistance either in the resistive state created by a bias current or in the normal state. The data obtained by means of pulse and modulation techniques are in agreement. The responsivity about 1 V/W was measured at 1 GHz modulation frequency both for 0.85 micrometers and 10.6 micrometers wavelengths. The sensitivity of high-Tc fast wideband infrared detector is discussed.
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Schwaab, G. W., Auen, K., Bruendermann, E., Feinaeugle, R., Gol’tsman, G. N., Huebers, H. - W., et al. (1998). 2- to 6-THz heterodyne receiver array for the Stratospheric Observatory for Infrared Astronomy (SOFIA). In T. G. Phillips (Ed.), Proc. SPIE (Vol. 3357, pp. 85–96). SPIE.
Abstract: The Institute of Space Sensor Technology of the German Aerospace Center (DLR) is developing a heterodyne array receiver for the frequency range 2 to 6 THz for the Stratospheric Observatory for Infrared Astronomy (SOFIA). Key science issues in that frequency range are the observation of lines of atoms [e.g. (OI)], ions [e.g. (CII), (NII)], and molecules (e.g. OH, HD, CO) with high spectral resolution to study the dynamics and evolution of galactic and extragalactic objects. Long term goal is the development of an integrated array heterodyne receiver with superconducting hot electron bolometric (HEB) mixers and p-type Ge or Si lasers as local oscillators. The first generation receiver will be composed of HEB mixers in a 2 pixel 2 polarization array which will be pumped by a gas laser local oscillator. Improved Schottky diode mixers are the backup solution for the HEBs. The state of the art of HEB mixer and p-type Ge laser technology are described as well as possible improvements in the ’conventional’ optically pumped far-infrared laser and Schottky diode mixer technology. Finally, the frequency coverage of the first generation heterodyne receiver for some important astronomical transitions is discussed. The expected sensitivity is compared to line fluxes measured by the ISO satellite.
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