Development of ultrashort pulse sources in the vacuum ultraviolet and terahertz for spectroscopy of advanced materials

Abstract

This proposal aims to develop laboratory-scale high photon flux sources of coherent radiation in vacuum ultraviolet (6 to 20 eV) and ultrabroadband terahertz (0.1 to 25 THz / 0.4 to 100 meV) using femtosecond lasers. The development of this coherent vacuum ultraviolet source constitutes the first step towards the construction of a laboratory scale beamline with parameters optimized for the Angle Resolved Photoelectron Emission (ARPES) technique. An ultrabroadband THz ultrashort pulse source will be developed in parallel and applied to the implementation of a terahertz time domain spectroscopy (THz-TDS) technique for steady-state and time-resolved THz spectroscopy of advanced materials.The high repetition rate (~1 MHz) VUV source proposed in this project will provide a photon flux comparable to synchrotron sources in the 6 - 20 eV range in a university laboratory scale experimental apparatus with the additional capability of time-resolved ARPES measurements. The intrinsic ultra-short nature of this VUV source (~ 100 fs) will allow the band structure characterization of advanced materials both in steady state and above Fermi energy states. The steady-state and time-resolved ultra-broadband THz-TDS technique will allow the complete spectral characterization of complex optical constants (real and imaginary components) of emerging materials thus providing essential information on low energy quasiparticles (phonons, excitons, polarons, magnons, superconducting gap, hybridization gap in heavy fermions, etc) and the charge carriers dynamics in their equilibrium and photoexcited states (photoconductivity) in bulk or nanoscale semiconductor systems.Therefore, the ultrafast VUV and THz sources to be developed in this project will open a new window of observation of the interactions that give rise to unconventional properties of complex quantum systems and the mechanisms of charge transport in semiconductor materials of interest in renewable energy research and electronics/optoelectronics. (AU)