High efficiency tunable unidirectional single-longitudinal-mode Er:YAG ring laser based on an acousto-optic modulator

Area of Science:

• Laser Physics
• Photonics
• Materials Science

Background:

• Erbium-doped Yttrium Aluminum Garnet (Er:YAG) lasers are crucial for various applications due to their emission around 1.6 µm.
• Achieving single-longitudinal-mode (SLM) operation in high-power ring lasers is challenging but essential for applications requiring narrow linewidth.
• Wavelength tunability and stable dual-wavelength operation enhance the versatility of laser sources.

Purpose of the Study:

• To demonstrate a wavelength-tunable, single-longitudinal-mode (SLM) Er:YAG ring laser operating near 1.6 µm.
• To investigate the laser's output power, slope efficiency, and wavelength tuning capabilities.
• To achieve stable dual-wavelength operation and record the highest continuous-wave SLM output power at 1617 nm.

Main Methods:

• Utilized an acousto-optic modulator (AOM) to enforce unidirectional operation for SLM output.
• Employed a birefringent filter (BRF) within the ring cavity for wavelength tuning.
• Measured laser output power, slope efficiency, linewidth using the time-delayed self-heterodyne method, and achieved dual-wavelength operation.

Main Results:

• Achieved up to 10.4 W and 8.7 W SLM output power at 1645.22 nm and 1617.33 nm, with slope efficiencies of 45% and 40%, respectively.
• Demonstrated stable dual-wavelength operation at 1645 nm and 1617 nm, reaching a maximum power of 9.1 W.
• Tuned the wavelength from 1616.77 nm to 1617.51 nm and 1644.51 nm to 1646.12 nm, with linewidths of 125 kHz and 131 kHz at 1617 nm and 1645 nm.

Conclusions:

• Successfully demonstrated a wavelength-tunable SLM Er:YAG ring laser with high output power.
• The achieved 8.7 W continuous-wave SLM output power at 1617 nm represents a new record.
• The laser's tunable and dual-wavelength capabilities offer significant potential for spectroscopic and photonic applications.