Self-seeded, Single-frequency Nd:YAG Q-switched Micro Laser with 1.7-ns, 1-mJ pulses at 1 kHz

Q-switched, single frequency lasers are essential for wide variety of applications such as high-resolution spectroscopy, LIDARs, optical communications and laser trapping or cooling. Such lasers operating at 1064 nm that are compact and provide high energy at high repetition rates are ideal seed sources for solid-state-bulk or fiber amplifiers. Following the demand of these applications, in the recent years a significant amount of effort is focused on the development of passively Q-switched microchip lasers. Besides, single longitudinal mode can be achieved in passive microchip oscillators with extremely thin gain materials [1], but this consequentially limits the amount of the generated energy per pulse. Although the passive microchip lasers are compact and robust devices their applicability is limited due to the inherent non-saturated losses in the absorber, which impose considerable limitation over achieving high levels of average power (~100mW) and poor ability for synchronization of the laser pulses with external electrical signals. Reducing the pulse-to-pulse timing jitter to ps-time scales requires elaborate optical schemes [2], that would increase the level of technical complexity. On the other hand, the microchip and mini lasers with active Q-switching overcome easily the time jitter issue in the laser synchronization. However, the introduction of an active modulator leads to increase of the optical length of the cavity eventually resulting in increase of the pulse duration over a few ns and therefore obtaining single frequency operation is more difficult and requires a different approach. Consequently, a laser generating ~1-nanosecond, single frequency, TEM00, milli-joule pulses with kHz repetition rate and high average power (≥ 1W) is at high demand. In this report we present an electro-optically Q-switched Nd:YAG micro laser with self-injection seeding, providing single-frequency, TEM00, 1.7 ns output pulses at 1064-nm, with 1 mJ, and 1 kHz repetition rate.