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

Abstract

Femtosecond optical response in GaAs thin films has been studied. We prepared GaAs thin films on MgO substrates and on YBa2Cu3O7-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.

Resonant terahertz radiation from Tl2Ba2CaCu2O8+δ thin films by ultrafast optical pulse excitation

“…Since the discovery of terahertz ͑THz͒ pulse radiation from photoconductive switching semiconductor device by femtosecond optical pulse ͑FOP͒ illumination by Auston et al, 1 THz pulse radiation phenomena from several kinds of materials have been discovered. [2][3][4] These materials have been used as an effective radiation source of THz wave to investigate the high-frequency properties of a variety of materials. THz radiation from semiconductors is well established and explained by photoexcitation of carriers followed by ultrafast modulation of photocurrent and locally induced polarization.…”

Coherent emission from surface Josephson plasmons in striped cuprates

“…The emission of THz radiation from materials illuminated with femtosecond optical pulses ( 4 – 7 ) is generally enabled by two classes of mechanisms. The first mechanism, active in transparent noncentrosymmetric materials such as ZnTe or LiNbO 3 , is based on optical rectification, where the second-order nonlinear optical susceptibility causes a time-dependent electrical polarization ( 8 ).…”