Coherent detection of pulsed narrowband terahertz radiation Available to Purchase

We demonstrate the generation and coherent detection of narrowband terahertz radiation using a $Q$-switched laser pumped optical parametric oscillator as the optical source. Narrowband terahertz radiation is produced using conventional difference frequency mixing and coherently detected via a frequency domain technique that relies on coherent upconversion of the terahertz field combined with optical homodyning to suppress background noise. GaSe crystals are used for both generation and coherent detection processes. Although we provide a proof-of-principle demonstration at $2THz$⁠, the infrared radiation may be tuned from the far-infrared through the midinfrared by simply tuning the idler wavelength of the optical parametric oscillator and the orientation of the two crystals.