High resolution continuous wave terahertz spectroscopy on solid-state samples with coherent detection.

We systematically investigate the data analysis methods in terahertz frequency domain spectroscopy (THz-FDS) with coherent detection. We demonstrate that the Hilbert transform method is one of the most appropriate for data processing in THz-FDS. By converting frequency-domain signal into time domain with further data processing, the system noise due to Fabry-Pérot (FP) interference is greatly restrained. Accurate permittivity of lactose monohydrate is successfully extracted under the condition of the existence of atmospheric water vapor. Our work greatly promotes the development of THz spectroscopy in practical applications.

Highly efficient generation of 0.2 mJ terahertz pulses in lithium niobate at room temperature with sub-50 fs chirped Ti:sapphire laser pulses.

We demonstrate generation of 0.2 mJ terahertz (THz) pulses in lithium niobate driven by Ti:sapphire laser pulses at room temperature. Employing tilted pulse front technique, the 800 nm-to-THz energy conversion efficiency has been optimized to 0.3% through chirping the sub-50 fs pump laser pulses to overcome multi-photon absorption and to extend effective interaction length for phase matching. Our approach paves the way for mJ-level THz generation via optical rectification using existing Ti:sapphire laser systems which can deliver Joule-level pulse energy with sub-50 fs pulse duration.