Efficient second-harmonic conversion of cw single-frequency Nd:YAG laser light by frequency locking to a monolithic...

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Diode-pumped solid-state lasers are crucial for various applications.
• Efficient frequency conversion is essential for generating specific laser wavelengths.
• Lithium niobate is a key material for nonlinear optical processes.

Purpose of the Study:

• To achieve efficient second-harmonic generation (SHG) of a Nd:YAG laser.
• To frequency lock the laser to a monolithic ring resonator for enhanced stability.
• To evaluate the long-term performance and reliability of the system.

Main Methods:

• Utilized a diode-pumped continuous-wave (cw) single-frequency Nd:YAG laser operating at 1064 nm.
• Employed a monolithic ring resonator made of magnesium-oxide-doped lithium niobate for frequency locking.
• Measured conversion efficiency and output power at 532 nm.

Main Results:

• Achieved 65% conversion efficiency from fundamental (1064 nm) to second harmonic (532 nm).
• Generated 200 mW of cw single-frequency 532-nm light from 310 mW of 1064-nm input.
• Demonstrated 20% overall efficiency from the 1-W diode laser pump source.
• Observed no degradation in 532-nm power or photorefractive damage for over 500 hours of operation at >100 mW green output.

Conclusions:

• Frequency locking to a MgO:LiNbO3 monolithic ring resonator enables highly efficient and stable second-harmonic generation.
• The system provides a robust source of single-frequency green light with excellent long-term stability and reliability.
• This approach is promising for applications requiring high-power, stable green laser sources.