Increase of generated tetrahertz wave from an In-As thin film by means of an optical coupler
Abstract
Increase of the generated pulsed terahertz wave from an InAs thin film excited by a femtosecond laser is reported. The InAs film thickness is 520 nm and is fabricated on a Si substrate. A Si hemispherical lens coupler is attached on the substrate side of the InAs THz emitter. A factor of 7.5 times increase in the amplitude of the THz wave from the InAs film with the lens coupler as compared to that of bare InAs has been observed. Further collimation of the radiated THz wave propagating through the lens coupler to air is thought to be the reason for the increase.