Frequency-tunable 500-mW continuous-wave all-solid-state single-frequency source in the blue spectral region.

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Compact, stable, single-frequency laser sources are crucial for various scientific applications.
• Second-harmonic generation (SHG) is a key technique for producing shorter wavelengths from existing lasers.
• Nd:YAG lasers are widely used but generating stable blue light directly can be challenging.

Purpose of the Study:

• To develop a compact and stable continuous-wave (cw) single-frequency radiation source at 473 nm.
• To investigate the efficiency and stability of second-harmonic generation using potassium niobate (KNbO3).
• To demonstrate frequency tuning capabilities of the generated blue light.

Main Methods:

• Utilized a diode-pumped miniature Nd:YAG ring laser operating on the (4)F(3/2) - (4)I(9/2) transition.
• Employed potassium niobate (KNbO3) as the nonlinear optical crystal for second-harmonic generation.
• Implemented an external semimonolithic cavity to achieve mode-hop-free frequency tuning.

Main Results:

• Achieved a compact source of stable cw single-frequency radiation at 473 nm.
• Obtained single-longitudinal-mode output powers of 500 mW cw with high stability.
• Reached maximum optical-to-optical conversion efficiencies exceeding 81%.
• Demonstrated mode-hop-free frequency tuning of the blue radiation over a range of 20 GHz.

Conclusions:

• A highly stable and efficient compact blue laser source at 473 nm has been successfully realized.
• The use of KNbO3 for SHG of a miniature Nd:YAG laser is effective for generating high-power blue light.
• The demonstrated frequency tuning capability enhances the utility of this laser source for advanced applications.