陶瓷多通道折叠射频波导稳频脉冲CO-(2)激光器研究

Study on ceramic multi-channel folded RF waveguide CO_2 laser

为了研究可用于红外激光外差成像雷达、由腔倒空脉冲工作模式的主振激光器和处于连续工作模式的本振激光器组成的射频波导稳频脉冲 CO_2激光器,采用输出端腔外准折叠和主、本振全反射端共用同一块原刻闪耀光栅的方法,分别缩短了器件的长度和提高了主、本振激光器的外差频率稳定性。通过调节 CdTe 调制器上的高压脉冲下降沿时间,可以使主振得到宽脉冲的腔倒空激光输出,本振通过插入压电陶瓷来实现系统的外差中频信号的偏频锁定。主振在腔倒空模式下工作重频可达到70kHz,得到脉冲峰值功率达到2.5kW(脉宽约为30ns)、主本振外差中频(120MHz)频率漂移在短期内小于1MHz 的结果。结果表明,研制的激光系统可以满足外差成像雷达系统的特殊要求。

In order to develop a frequency-stabilized cavity-dumped RF waveguide CO2 laser to be used in a pulsed heterodyne imaging lidar, a laser system, composed of a pulsed master laser （MO） and a continuous wave local laser （LO） was studied,in which the same original blazed diffraction grating was set on the total reflective end of LO and MO because of the ceramic-plate folded-channel structure, so the physical length was shorten and the frequency stability of both the LO and MO was improved. In order to increase the width of the cavity-dumped output pulse, a delay circuit was employed to lengthen the falling time of the high voltage applied to the CdTe modulator. The frequency offset between the MO and LO radiation was locked with a piezoelectric ceramic. So the peak power of the MO was about 2.5kW with a pulse width of 30ns （full width at half maximum, FWHM） at a repetition rate of 70kHz, and the frequency offset between the MO and LO radiations was less than 1 MHz in a short term. The testing results show that the laser system can meet the requirement of the pulse heterodyne imaging lidar system.