Optical Response in Amorphous GaAs Thin Films Prepared by Pulsed Laser Deposition

Femtosecond optical response in GaAs thin films has been studied. We prepared GaAs thin films on MgO substrates and on YBa 2 Cu 3 O 7-δ (YBCO) thin films using pulsed laser deposition (PLD) at temperatures below 250°C. A photocarrier lifetime of less than 1 ps is measured for the prepared GaAs thin films using femtosecond time-domain reflectivity change measurements. Pulsed electromagnetic wave [terahertz (THz) radiaiton] containing a frequency component of up to 1 THz is emitted from fabricated photoconductive switches using the prepared thin films. We also evaluated the THz radiation properties emitted from the photoswitches on the YBCO thin films.