Achievement

IGERT trainee Xiaofei Lu will graduate with a PhD in June and has a job offer from a wafer company. She [1] invented a balanced detection method to improve the signal to noise ratio and dynamic range of current THz-ABCD (Air Biased Coherent Detection) systems. Utilizing the tensor property of third-order nonlinear susceptibility, second harmonic pulses with two orthogonal polarizations are detected by separated photomultiplier tubes. The balanced THz-ABCD offers a realistic method for handling laser fluctuation; [2] demonstrated a direct approach to produce an arbitrary elliptically polarized broadband THz pulses by applying a helical electrical field along plasma region. The observed THz wave polarization reveals the prominent role of velocity retardation between optical pulses and generated THz pulses in the generation process. Results obtained from simulations are in good agreement with experimental findings and clarify the mechanisms responsible for THz polarization control.