Extraction method for superimposed coherent transition radiation using Fresnel reflection in a ring-type resonator

Abstract

To generate terahertz pulses with a high peak power, a pulse train of coherent transition radiation (CTR) is superimposed by circulating it in a ring-type resonator at an L-band electron linear accelerator facility at the Kyoto University Institute for Integrated Radiation and Nuclear Science. By extracting the superimposed CTR pulses from the ring-type resonator via Fresnel reflection on a low-loss parallel substrate, we show that the cavity loss can be suppressed without being affected by the wavenumber of the CTR pulses. The power of the superimposed CTR pulse is increased to approximately four times that of a CTR generated by plane mirrors in the resonator at a wavenumber of 8.5cm−1, where the diffraction loss of the resonator is lower. Using shorter electron bunches to generate CTR pulses with higher wavenumbers increases the amplification factor caused by superposition and allows CTR pulses with a higher peak power to be generated.