| Abstract [eng] |
This work is dedicated to explore new technological solutions for room temperature compact spectroscopic terahertz (THz) imaging systems involving all basic components such as emitters, amplifiers, optics, and detectors. THz source based on p-i-n-i -type GaAs/AlGaAs heterostructure was experimentally investigated for the first time. It is demonstrated that under certain excitation conditions by femtosecond optical pulses the emitter delivers more power than InGaAs and InAs surface emitters. As concerns a potential amplification medium for THz radiation, wide-miniband GaAs/AlGaAs superlattice-based diode structure is investigated. By adapting theoretical principals of controlled injection, suitable conditions to achieve homogenous electric field profile required for Bloch gain were determined. By applying these conditions, signatures of Bloch gain was observed experimentally in microwave frequency range. Multimode laser operating in TEM01 mode was successfully applied for high resolution THz imaging. Innovative THz detectors – asymmetrically shaped InGaAs diodes – were applied for spectroscopic THz imaging. Sensors were used to record THz images of samples containing sucrose and tartaric acid and to determine their principal component distribution in the frequency range of 0.5¬–2.5 THz. Frequency range was extended up to 4.2 THz by applying nanometric field effect transistors. THz detectors based on Titanium microbolometers were successfully employed in spectroscopic imaging system with low average power optoelectronic emitter. |
