Terahertz Application Technology Research

Terahertz (THz) waves are those with frequencies between 300 GHz to 10 THz. With the location of the spectrum between the electronic and photonic domains, THz waves contain rich information involved in molecular vibration and rotation, and have sub-picosecond pulse width, low photon energy and high space-time coherence. These unique features are indeed tremendous and imply astonishing applications in various areas of science such as astronomy, biology, computers and communications. During recent 20 years, a great deal studies developed quickly covering THz generation, detection and applications. This thesis researched main THz application techniques nowadays based on the reading of lots of documents. The details are as follows:Analyze the main methods and technologies for THz generation, detection and processing, and focus on the physical principles and effects on which these techniques are based. At the same time, THz time-domain spectroscopy (THz-TDS) and THz computed tomography (THz CT) are studied in detail.Study the way to extract sample parameters from THz waveform in THz-TDS and give the simulation study. On the base of a set of known signals, we get the ideal curves of refraction and absorption coefficients using Fourier transform and transmission spectroscopy model. More, some influencing factors are discussed.Analyze the error caused by small changes of the optical path of THz beam in reflection spectroscopy. These changes take place due to replacement of the sample. Both qualitative and quantitative analyses are given. And introduce a kind of improved method to reduce the measurement error efficiently.Introduce a high resolution algorithm for THz two-dimensional CT, which takes advantage of Wiener filtering and fits the imaging system of THz CT. A simulation for a THz CT image shows that this algorithm can greatly improve its resolution.Introduce the design scheme of an infrared simulation system. Considering the high cost of a THz CT system, it is reasonable and feasible to establish a low cost infrared CT system for simulation study currently. This system makes use of sector-scanning model and has three subsystems. Algebra reconstruction technique (ART) is employed in this system and proved having good performance in image reconstruction through numerical simulation.