Abstract-Continuous-wave 1550 nm operated terahertz system using ErAs:In(Al)GaAs photo-conductors with 52 dB dynamic range at 1 THz

A.D.J. Fernandez Olvera, H. Lu, A. C. Gossard, and S. Preu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-23-29492

Telecom-wavelength compatible photoconductors benefit strongly from the large amount and affordability of telecom lasers and components but there are demanding requirements on material development. We demonstrate continuous-wave (CW) photomixing with a setup that only uses ErAs:In(Al)GaAs devices with a peak dynamic range (DNR) of 78 dB and a bandwidth of ∼3.65 THz at an integration time of 300 ms and only 26 mW laser power on each device. The ErAs:InGaAs receiver further features a factor of two lower noise equivalent power (NEP) than a state-of-the-art photoconductor, despite an antenna mismatch.

© 2017 Optical Society of America under the terms of the OSA Open Access Publishing 

Abstract-Free-Standing Guided-Mode Resonance Humidity Sensor in Terahertz

Hee JunShin, Sae-HyungKim, KisangPark, Min-CheolLim, Sung-WookChoi, Gyeongsik Ok, 

http://www.sciencedirect.com/science/article/pii/S0924424717308646

We theoretically and experimentally investigate a polymer-based guided-mode resonance (GMR) structure and its application for relative humidity (RH) sensing in the terahertz region. We obtained RH-dependent resonance frequency shifts and transmittance changes of the free-standing polymer GMR sensors with PVA material coating at 20 °C. We numerically simulated the GMR structure in the same frequency region by using the FDTD method. It shows that the water contents in the polyvinyl alcohol (PVA) film are increased up to 6% as RH is increased up to 70%. As a result, we propose a highly sensitive RH sensor, which can be fabricated by a simple method at low cost for widespread usage.

Abstract-Optical frequency switching scheme for a high-speed broadband THz measurement system based on the photomixing technique

Hajun Song, Sejin Hwang, and Jong-In Song

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-10-11767&origin=search

This study presents an optical frequency switching scheme for a high-speed broadband terahertz (THz) measurement system based on the photomixing technique. The proposed system can achieve high-speed broadband THz measurements using narrow optical frequency scanning of a tunable laser source combined with a wavelength-switchable laser source. In addition, this scheme can provide a larger output power of an individual THz signal compared with that of a multi-mode THz signal generated by multiple CW laser sources. A swept-source THz tomography system implemented with a two-channel wavelength-switchable laser source achieves a reduced time for acquisition of a point spread function and a higher depth resolution in the same amount of measurement time compared with a system with a single optical source.

© 2017 Optical Society of America

Abstract-Methods of spectrally pure two-frequency radiation forming for terahertz carriers generation in optical range

Rustam A. Khabibullin ;  Oleg G. Morozov ;  Airat Z. Sakhabutdinov ;  Ilnur I. Nureev

http://ieeexplore.ieee.org/document/7997568/

One of the promising methods for generating continuous terahertz radiation is the method of photomixing, when the photoconductive material is excited by the emission of two optical continuous lasers with frequencies separated by terahertz frequencies. It should be noted that for effective photomixing the polarization, frequencies and phases of the optical beams introduced into the mixer must be constant, otherwise it is necessary to additionally use a complex system of phase synchronization. In connection with the complexity of such an implementation, variants based on the conversion of single-frequency and broadband laser radiation into two-frequency ones were investigated. The first of these is modulation and consists in the external modulation of single-frequency laser radiation in the electro-optical Mach-Zehnder modulator. The second one is broadband with the allocation of two wavelengths using two rectangular fiber Bragg gratings with a small difference in width.