Title :
Ultrafast nonbolometric photoresponse of YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films
Author :
Ghis, A. ; Pfister, S. ; Villegier, J.C. ; Nail, M. ; Maneval, J.P.
Author_Institution :
LETI-CEA Technol. Avancees, Grenoble, France
fDate :
3/1/1993 12:00:00 AM
Abstract :
Ultrafast transient voltage (<12-ps risetime, 30-ps width) has been measured on a current-biased, very thin (30-nm) YBa/sub 2/Cu/sub 3/O/sub 7-x/ epitaxial film, illuminated by a picosecond laser pulse ( lambda =1.06 mu m) at approximately 50 K. The experimental set-up and the measuring apparatus used allowed precise time measurements. The narrow and high electric pulse obtained is faster than any previously reported. It is attributed to a nonequilibrium Cooper pair breaking process. This first response pulse is followed by a longer bolometric decay interpreted using parameters obtained from measurements taken at smaller fluence and lower temperature as the combination of a phonon escape time and an electron-phonon energy relaxation time.<>
Keywords :
Cooper pairs; barium compounds; high-speed optical techniques; high-temperature superconductors; infrared detectors; photodetectors; superconducting epitaxial layers; superconducting junction devices; yttrium compounds; 1.06 micron; 50 K; HTSC; IR photodetectors; YBa/sub 2/Cu/sub 3/O/sub 7-x/; current-biased; electron-phonon energy relaxation time; epitaxial film; nonequilibrium Cooper pair breaking; phonon escape time; picosecond laser pulse; transient voltage; ultrafast nonbolometric photoresponse; Coaxial components; Optical films; Optical pulses; Optical pumping; Pulse measurements; Pulsed laser deposition; Superconducting films; Time measurement; Transistors; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
