Study of Tera Hertz Generation Processes in Doped GaSe Crystals
|Keywords:||兆赫波;非線性光學晶體;硒化鎵晶體;差頻產生;偶極天線;THz;nonlinear optical crystals;GaSe crystals;difference frequencygeneration;dipole antenna|
This proposal is intended to find a new doping element in nonlinear optical semiconducting crystals, GaSe, for high efficiency terahertz (THz) generation. GaSe crystals which will be the main subject of the research within this proposal are among the most prospective IR-range crystals. In last years the possibility to create tunable terahertz generation sources on its base was demonstrated by experiments. GaSe possesses the lowest absorption in the terahertz range among known nonlinear crystals. Therefore the crystals are prospective for THz generation by nonlinear-optical conversions (difference frequency generation, DFG). On the other hand, the efficiency of conversion and the power of output radiation are limited by crystal properties such as optical transparency and homogeneity. In particular at DFG the increasing crystal length must give higher conversion efficiency that is not observed in real experiments. The answer should be given what limits the possibilities of the crystals and whether it is possible to improve them, for example by introducing chemical elements with bigger atomic radius and higher polarizability. The second method to generate THz is employing of dipole antenna scheme. For enhancement of efficiency of such devices it is necessary to use materials with high resistance and carrier mobility. Electrical transport properties of GaSe can be considerably modified by doping and it looks reasonable to investigate dipole antennas based on doped crystals, which also should give information on their electronic properties. Within this proposal it is planed to find conditions of growth of large homogeneous GaSe crystals with lower absorption in THz region and investigation of possibilities to enhance their characteristics by the way of their doping for creation on their base of optical elements for THz range generators and frequency converters. In particular the problem is to reveal the mechanisms determining the optical transparency of nonlinear optical crystals in the specified range. The task is to develop scientifically based and stable schemes to produce nonlinear optical single crystals with improved parameters for applications in the THz range. Finally, after getting the suitable nonlinear optical crystals for high power and widely tunable wavelength THz generation, we could study the ultrafast dynamics in some interesting materials such as high Tc superconductor, multiferroics manganites, magnetic semiconductors or semiconductor quantum dots et. al..
|Gov't Doc #:||NSC96-2923-M009-001-MY3|
|Appears in Collections:||Research Plans|