title: Quasi-near field terahertz generation and detection.
abstract: We describe a simple terahertz (THz) time domain spectrometer with a bandwidth extending up to 7.5 THz. We show that by keeping the generation and detection crystals close to each other a high signal-to-noise ratio (SNR) can be achieved without using lock-in detection and dry nitrogen flushing. The observed spectra show very good agreement with the spectra calculated based on a simple model which includes phase matching and absorption in the generation and detection crystals. Using this set-up we have measured the absorption lines in D-tartaric acid from 0.5 THz up to 7 THz. We show that the high frequency region > 3 THz is the better choice to measure small changes in the water content of a hygroscopic sample compared to the low frequency region.
authors: 1Department of Imaging Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands. r.chakkittakandy@tudelft.nl
authors: Reshmi
authors: R
authors: Chakkittakandy
authors: Jos A
authors: JA
authors: Corver
authors: Paul C
authors: PC
authors: Planken
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007259:Infrared Rays; D008029:Lighting / Q000295:instrumentation* / Q000379:methods; D008872:Microwaves; D013055:Spectrophotometry, Infrared / Q000295:instrumentation* / Q000379:methods; D014159:Transducers