Room Temperature, THz Photomixing Sweep Oscillator and Its Application to Spectroscopic Transmission Through Organic Materials
Document Type
Article
Publication Date
12-1-2004
Identifier/URL
40303723 (Pure); 20444505234 (QABO)
Abstract
An all-solid-state continuous-wave sweep oscillator has been developed that provides high-resolution, transmission measurements between ∼30 GHz and 3 THz . It is based on difference-frequency generation between two cw frequency-offset lasers driving an ultrafast photoconductive mixer (photomixer). The output power around 100 GHz is approximately 10 μ W , falling to about 1 μ W around 1 THz and 0.1 μ W around 3 THz . The sweep oscillator is used with two types of detectors: a hot electron bolometer for high-sensitivity measurements of weak absorption features below 1 THz , and a room temperature Golay cell for coarse measurements anywhere between 30 GHz and 3 THz . The sweep oscillator facilitates the rapid characterization of a broad variety of materials including inorganic solids, biological materials, liquids, and gases with far greater resolution (∼10 MHz ) , frequency accuracy (∼0.1 GHz ) , and spectral density (∼1 μ W / MHz ) than competitive wideband instruments such as Fourier-transform or time-domain spectrometers. To demonstrate the versatility of the sweep oscillator, results are presented for two diverse cases of interest: (1) fast scan, broadband (>1 THz ) absorption profiles from biomaterials such as polysaccharides, and (2) slow scan, narrow-band (∼1 GHz ) atmospheric lines from water vapor.
Repository Citation
Brown, E. R.,
Bjarnason, J.,
Chan, T. L.,
Driscoll, D. C.,
Hanson, M.,
& Gossard, A. C.
(2004). Room Temperature, THz Photomixing Sweep Oscillator and Its Application to Spectroscopic Transmission Through Organic Materials. Review of Scientific Instruments, 75 (12), 5333-5342.
https://corescholar.libraries.wright.edu/physics/1332
DOI
10.1063/1.1808912
