Towards terahertz dual-comb spectroscopy based on quantum cascade lasers

Abstract

In this thesis, terahertz (THz) laser frequency combs are improved and THz dual-comb spectroscopy method is demonstrated. To achieve better performance of THz quantum cascade laser (QCL) frequency combs, several broadband homogeneous and heterogeneous gain media are characterized, and corresponding dispersion compensators are designed. All THz QCL frequency combs are fabricated in Microsystems Technology Laboratories at MIT using our group's standard process. By utilizing the broad spectral coverage of THz QCL frequency combs and the multiheterodyne detection method, a prototype of the THz dual-comb spectrometer is demonstrated. This thesis work provides an important step towards realizing laser-based broadband THz spectroscopy system for chemical identification and explosive detection.