Characteristics of Photogenerated Bipolar Terahertz Radiation in Biased Photoconductive Switches

Exploring Dynamics in the Far-Infrared with Terahertz Spectroscopy

“…Later Tonouchi et al carried out a temperature-dependence study and quantified the quasiparticle recombination time. ,, They found that the recombination time increased from about 0.3 ps at 10 K to about 2 ps at 70 K. Their results are not directly comparable to those of Jaekel and co-workers because Jaekel et al carried out their analysis in the frequency domain, while Tonouchi et al worked in the time domain. These results have recently been largely confirmed by Lin et al using a detector based on FSEOS rather than a photoconductive antenna …”

“…These results have recently been largely confirmed by Lin et al using a detector based on FSEOS rather than a photoconductive antenna. 24 Tonouchi et al also investigated flux-trapping in YBCO thin films. 197,198 To carry out these experiments, they utilized a cylindrical magnet in close proximity to the superconducting film to provide a magnetic field of ∼150 G perpendicular to the surface normal (see Figure 7) 197 rather than a bias current.The sample is cooled to 11 K in the absence of a magnetic field.…”

“…Use of photoconductive antennas is the oldest method for generating and detecting THz pulses. − It is based on the process of using an above-band-gap laser pulse to generate carriers in the conduction band of a semiconductor under an applied bias voltage. The bias accelerates the newly formed carriers, yielding an electromagnetic pulse.…”

“…Terahertz emission from high- T c superconductors (HTSCs), particularly YBa 2 Cu 3 O 7 - δ (YBCO), has also been a topic of considerable attention. ,− It is possible to characterize the dynamics of Cooper pair breaking and recombination. Also, HTSCs show promise as high-speed optical detectors, and understanding the relaxation of photoexcited quasiparticles is required.…”