TRANSIENT RESISTIVE PHOTORESPONSE OF YBA2CU3O7-DELTA FILMS USING LOW-POWER 0.8 AND 10.6 MU-M LASER-RADIATION

Thin YBa2Cu3O7-delta laser deposited films were patterned into devices consisting of ten parallel 1 mum wide strips. Nonequilibrium picoseco nd and bolometric photoresponses were studied by the use of 17 ps full width at half-maximum laser pulses and amplitude modulated radiation from an AlGaAs laser up to 10 GHz and from a CO2 laser up to 1 GHz. Th e time and frequency domain measurements were in agreement. The fast r esponse can be explained by electron heating. The use of low optical p ower and a sensitive measurement system excluded any nonlinear transie nt processes and kinetic inductance changes in the superconducting sta te. At 1 GHz modulation frequency, the responsivity was approximately 1.2 V/W both for 0.8 and 10.6 mum wavelengths. The sensitivity of a fa st and spectrally broadband infrared detector is discussed.