Developmental Research of a Tunable Far Infrared Laser Using Germanium

在项目开始之前，唯一可用的振荡是旧波导模式，当锗样品本身作为光学谐振器时。在这个项目中，已经取得了以下总结的进展，导致在振荡频谱的整个范围内进行波长机械调谐的前景广阔。1)在带外镜的半焦谐振腔中实现了轴向模的振荡。因此，激光束的方向性得到了显著改善，从而可以详细研究光谱、偏振和振荡增益系数。2)波长选择是通过在共振器中加入一个额外的结构来作为Fabri-Perot干涉仪来尝试的。虽然该原理在实验中得到了证实，但由于增益系数相对较小，从应用角度来看，选择性并不完全令人满意。结果表明，提高增益系数对波长的选择和调谐是必要的。3)为了提高增益系数，开展了单轴应力下振动的研究，取得了显著的效果，为今后的工作提供了良好的前景。

Berofe the project had started, the only oscillation available was od waveguide modes wher Germanium specimens by themselves sereve as the optical resonator. In this project, the developments summarized below have been achieved leading to promissing prospects for mechanical tuning of wavelength over entie range of oscillation spectrum.1) Oscillation of axial modes was achieved in semiconfocal resonators with external mirrors. The directivity of the laser beam was thereby improved significantly, making possible detailed studies of the spectrum, the polarization and he gain-coefficient of oscillations.2) Wavelenght selection was attemped by incorporation an additinal structure into the resomator to work as a Fabri-Perot interfermeter.Although the principle was confirmed to work in the experiments, the selectivity was not completely satistactory in veiw of application vecause of relatively small gain-coefficients. It thus turned out the improving the gain-coefficients is necessary for the selection and the tuninf of wavalength.3) To improve gain-coefficients, studies of oscillation under uniaxial stress has been carried out, which proved to be strikingly effective thus providing promissing prospects for the future work.