Q-switched single-longitudinal-mode Nd:YAG laser based on composite mode selection mechanism

Abstract An electro-optical modulator (EOM) Q-switched Nd:YAG pulsed laser at 1.06 μ m with single-longitudinal-mode (SLM) output is demonstrated. The enhancement of the longitudinal mode selection and the generation of SLM are provided by both the birefringence filtering technique by fine-tuning the EOM and the reflection interferometer compound cavity. The working principles of composite longitudinal mode suppression techniques are analyzed theoretically. Experimentally, we also verified that by using the composite longitudinal mode suppression techniques, the SLM operation with a high SLM ratio of up to 100% during a 1 h test is maintained without a feedback loop. The SLM laser operates at a repetition frequency of 500 Hz, producing 60 ns pulses with a pulse energy of 183.6 μ J. The result indicates that the proposed method is a simple and effective scheme for improving the stability of SLM operation.