Laser Offset Stabilization for Broadly Tunable TeraHertz (THz) Frequency Generation

• Main Author: Cossel, Kevin
• Published: 2007
• Online Access: Cossel, Kevin (2007) Laser Offset Stabilization for Broadly Tunable TeraHertz (THz) Frequency Generation. Senior thesis (Major), California Institute of Technology. doi:10.7907/S7V2-JJ56. https://resolver.caltech.edu/CaltechTHESIS:02132018-104318011 <https://resolver.caltech.edu/CaltechTHESIS:02132018-104318011>

Spectroscopy and imaging in the terahertz region promises to be useful for a wide variety of applications. For remote sensing, terahertz spectroscopy could help in the identification of explosives and narcotics. In astronomy, terahertz imaging should provide new information about the composition of the interstellar medium and about the processes by which stars and planets are born. In chemistry and molecular biology, terahertz spectroscopy provides new rotational or rovibrational spectra of molecules and is useful in the study of hydrogen-bound clusters that serve as model systems for the quantitative understanding of the intermolecular forces involved in (bio )polymers and aqueous media. However, there are currently no terahertz sources that are easily tunable over the full region with high precision and accuracy. Here, we discuss the development of a novel three-laser source that allows for accurate stabilization of the difference frequency between two diode lasers to any frequency up to several terahertz, while still maintaining a long-term linewidth of under 10 MHz. When coupled with new traveling-wave photomixers, we will have a narrow linewidth, broadband terahertz source with high accuracy and capable of delivering up to tens of microwatts of power.