Fig. 1. Layout of the newly developed TPA pump system

Fig. 2. Self-designed crystal mounting frame integrated with a collimator

Fig. 3. Simulation results. (a) Simulated resonate beam propagation in the RA cavity; (b) seed laser matching into the cavity

Fig. 4. Laser beam radius in the Nd∶‍YVO₄ crystal with different focal length of thermal lens

Fig. 5. Maximum output power after different numbers of round trips for a series of pump powers

Fig. 6. Output laser performance of the RA. (a) Plots the spectrum together with the seed; (b) plots the transverse profile with fitted Gaussian curves in horizontal and vertical directions; (c) plots the autocorrelation signal and Gaussian fitting result of the RA; (d) plots an 8 h power monitoring of RA output