Study On THz Detection Technology Based On Optical Methods

Compared to microwaves, infrared and X-ray, THz-wave has its uniquecharacteristics, and its research and applications involve physics, life sciences,information technology, communication, astronomy, national defense security and soon. THz-wave parametric oscillator(TPO) based on stimulated polariton scattering hasmany advantages, such as high efficient, tuning, narrow width and room temperatureoperation. THz-wave detection using a parametric process has the advantages of highdetection sensitivity in room temperature and obtaining the energy and waveforminformation at the same time. The Brewster technique is a method for measuring theabsorption, which is easy to use and has a high-precision. The main contents of thispaper are the THz-wave detection using a parametric process and measuring theabsorption in THz range using the Brewster technique.The main contents and key innovative points are as follows:1. The characteristics and applications of THz-wave are introduced, we focus onthe THz-wave detection technology and elaborate the several common THz-wavedetection technology.2. The working principle of THz-wave detection using a parametric process isintroduced and we discuss the model and theory derivation. The detection sensitivityis computed in the range between0.1THz to10THz, and the detection sensitivity fordifferent pump power and different gain lengths is numerically simulated. Computingthe detection sensitivity in different temperature, we find that the high-frequency（1.5THz<υT<5THz） detection sensitivity decreases with temperature rise and thelow-frequency（υT<1.5THz）detection sensitivity increases with temperature decreaseaccording the numerical simulation results.3. The surface emitted THz-wave experiment device(TPO) is built, and theoutput THz-wave frequency is in the range of1THz to2.8THz. The maximumTHz-wave energy is195nJ/pulse at1.57THz. Using above output THz-wave as thedetected THz-wave source, the experimental study of THz-wave detection using aparametric process is conducted. We observe difference-frequency idler light bymixing pump light and THz-wave. 4. Theoretical investigation and experiment of measuring sample absorptionbased on Brewster technique are developed. Using Brewster technique, the absorptioncoefficient of polythene is measured. By the data fitting, we obtain the absorptioncoefficient is0.57305±0.0258cm-1and the error analysis is conducted.