Acousto-optically induced single-frequency Nd:YAG ring laser based on double corner cube retroreflectors

Area of Science:

• * Laser Physics and Photonics
• * Nonlinear Optics and Laser Engineering

Background:

• * Achieving stable, unidirectional operation in ring lasers is crucial for various applications, including spectroscopy and laser material processing.
• * Traditional methods often involve complex cavity designs or active feedback systems, limiting robustness and increasing cost.
• * Corner cube retroreflectors (CCRs) offer inherent alignment stability but typically support bidirectional oscillation.

Purpose of the Study:

• * To demonstrate, for the first time, the use of an acousto-optic modulator (AOM) to enforce unidirectional operation in a Nd:YAG ring laser utilizing double corner cube retroreflectors (CCRs).
• * To investigate the performance of this configuration in both continuous-wave (CW) and Q-switched modes.
• * To assess the impact of cavity misalignment on the laser's stability and output characteristics.

Main Methods:

• * Implementation of an acousto-optic modulator (AOM) within a Nd:YAG ring laser cavity incorporating double CCRs.
• * Controlled tilting of the AOM relative to the Bragg angle to introduce differential diffraction loss for counterpropagating beams.
• * Modulation of the AOM's radio frequency (RF) drive to achieve both CW and pulsed (Q-switched) laser operation.

Main Results:

• * Successful demonstration of CW single-frequency operation with a maximum output power of 2.99 W at 1064.5 nm, tunable from 1064.3 nm to 1064.7 nm.
• * The unidirectional ring cavity exhibited significant tolerance to cavity misalignment.
• * Achieved unidirectional Q-switched operation with pulse energies up to 0.882 mJ (70.2 ns pulse width) at 12.6 kW peak power, and 0.761 mJ (72.4 ns pulse width) at 10.5 kW peak power.

Conclusions:

• * The AOM-based method effectively enforces unidirectional oscillation in a Nd:YAG ring laser with double CCRs.
• * The demonstrated laser system offers robust performance with high tolerance to misalignment, making it suitable for demanding applications.
• * The ability to achieve both stable CW and high-energy Q-switched single-frequency pulses highlights the versatility of this laser configuration.