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An intracavity frequency doubling electro-optically Q-switched Nd:YLF 523.5 nm laser is developed. An appropriate cylindrical lens is employed in the oscillator to optimize the mode size and to improve the stability of the cavity. With an incident pump pulse energy of 58 mJ at a 500 Hz repetition rate, a green pulse energy of 16.8 mJ at 523.5 nm is obtained, corresponding to an optical-optical conversion efficiency of 29%. The pulse width is less than 8 ns, and the beam quality factor is 𝑀 2 ≤ 2.5.

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A laser diode dual-end-pumped injection-seeded single-frequency Q-switched double-pulse Nd:YAG laser is designed using a modified ramp-fire technique. The laser is capable of producing a pair of Q-switched single-frequency 1064 nm laser pulses in one pump period. Every pulse has an output energy of up to 10 mJ, width of nearly 20 ns, and interval of about 200 μs between two Q-switched pulses. The optical-to-optical efficiency of this laser is about 22.4% and its slope efficiency is 28%. A narrow spectrum linewidth of less than 28.6 MHz with a frequency of jitter around 1 MHz over 2 min may be obtained, and a beam quality of 1.23 in the horizontal direction and 1.31 in the vertical direction is detected.

The influences of nutation trail accuracy, simplification of coupling model, spot position jitter, and power variation of incident light on the detection error are analyzed theoretically. Under the condition of satisfying the requirements, the nutation radius is less than 1.13 μm, the accuracy of the nutation trail is less than 0.04 μm, and the detection range is [−5 μm, +5 μm]. The nutation frequency is 160 times spot position jitter frequency and 100 times intensity jitter frequency of incident light. The analysis is of great significance for determining nutation radius and frequency in the tracking system based on fiber nutation.