|The design of Razeghi's tunable terahertz source includes two sampled gratings (SG1 and SG2) and a distributed Bragg reflector (DBR). Image: Northwestern Engineering)
Current terahertz sources are large, multi-component systems that sometimes require complex vacuum systems, external pump lasers, and sometimes cryogenic cooling. Now Manijeh Razeghi and her colleagues at Northwestern University (Evanston, IL) have developed a new type of terahertz emitter that bypasses these issues.1 The small, room-temperature device, which emits in wide frequency range (1 to 5 THz), is based on intracavity difference frequency generation emitted by a strong-coupled strain-balanced quantum cascade laser design.
The emitter produces single-mode terahertz radiation at output powers up to 14 μW. With the ability to detect explosives, chemical agents, and dangerous biological substances from safe distances, the device could make public spaces more secure.
“A single-component solution capable of room temperature continuous wave and widely frequency tunable operation is highly desirable to enable next generation terahertz systems,” says Razeghi.
This new research builds on Razeghi group’s many years of research with Northwestern’s Center for Quantum Devices, including the development of the first single-mode room-temperature terahertz laser in 2011.
1. Quanyong Lu et al., Nature Communications (2016); doi: 10.1038/srep23595