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Study On Difference-freqency Generation Of Terahertz Waves And Low Loss Waveguides For Terahertz Transmission

Posted on:2010-01-19Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y F GengFull Text:PDF
GTID:1118360302995130Subject:Physical Electronics
Abstract/Summary:PDF Full Text Request
Terahertz (THz) radiation exhibits great potential applications in the areas such as spectral analysis, medial imaging, environmental monitoring and military security. Now many methods have been employed to obtain the THz radiation including electronics and photonics methods, and among them the difference-frequency generation (DFG) of terahertz wave based on the nonlinear optical frequency maxing has attracted great interest for its numerous advantages of operating at room temperature such as widely tunable range, high peak power, low cost and compactness. However, the researches of the terahertz-wave DFG and the low-loss terahertz waveguides in our country just started and were reported very few, so in this project, we put our attention to the THz-wave DFG and low-loss practical terahertz waveguides, the main contents and the creative points are as follows:1. According to the coupled-wave equation, the energy transfer among the three waves has been studied in the process of the terahertz-wave DFG and the absorption effect on the output power of terahertz wave has bee疤?alyzed. The phase matching angle, tuning curves and the effective nonlinear coefficient are calculated.2. Using a 532nm green laser with repetition frequency of 10Hz and pulse width of 10ns as a pumped source, a dual-wavelength KTP optical parametric oscillation operating at the degenerated point around 1064nm is realized. The terahertz radiation is obtained by the dual-wavelength DFG in the crystal of GaSe, and the terahertz-wave frequency could be tuned from 0.41THz ~3.3THz. Based on a internal pumped KTP optical parametric oscillation with repetition frequency of 10Hz, a dual-wavelength output is realized operating around the degenerated point of 2128nm, and the terahertz radiation with tuning range of 0.147THz~3.65THz (82μm~2041μm) and peak power of 10mW~17mW is obtained.3. Based on the internal pumped dual-wavelength KTP optical parametric oscillation, the mid-infrared radiation with tuning range of 8.42~19.42μm is obtained, and the maximum energy for the type I and type II phase matching are 4.17μJ and 3.65μJ.4. The hollow-core terahertz waveguide internally coated with metal film Ag is investigated theoretically and experimentally. The properties such as mode field distribution, transmission loss and cut-off frequencies for lower-order modes of TE11, TE01, TM01 and TE21 are studied and the effect of structural parameters of the waveguides on the transmission loss is analyzed. The hollow-core metal waveguide with diameter of 1.1mm is made, and the transmission loss of 8.6dB/m at 2.5THz is realized. The hollow-core metal/dielectric film terahertz waveguide are also investigated and designed.5. The low loss micro-structured plastic terahertz fibers are designed using the finite difference method and finite element method, and the transmission loss and dispersion of solid-core plastic photonic crystal fiber and hollow-core plastic photonic bandgap fiber are analyzed. The plastic photonic bandgap fibers with hexagonal air hole cladding and large fill factor have been used firstly to realize low loss terahertz guiding, and the minimum loss of 0.268dB/m is achieved.
Keywords/Search Tags:terahertz radiation, difference-frequency generation, hollow-core metal terahertz waveguide, micro-structured terahertz fiber
PDF Full Text Request
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