Application of a continuously tunable, cw optical parametric oscillator for high-resolution spectroscopy

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Spectroscopy
• Nonlinear Optics

Background:

• High-resolution spectroscopy requires stable, tunable, narrow-linewidth light sources.
• Optical Parametric Oscillators (OPOs) offer broad tunability but often require complex setups or high pump powers.
• Doubly resonant OPOs can achieve low thresholds but typically suffer from mode hopping and limited tuning ranges.

Purpose of the Study:

• To demonstrate a smoothly tunable, single-frequency continuous-wave optical parametric oscillator (OPO) for high-resolution spectroscopy.
• To achieve a low pump power threshold using a potassium titanyl phosphate (KTP) based doubly resonant OPO.
• To showcase the device's practicality by recording the absorption spectrum of cesium vapor.

Main Methods:

• Utilized a potassium titanyl phosphate (KTP) crystal in a doubly resonant optical parametric oscillator (OPO) configuration.
• Achieved resonance for both signal and idler fields to significantly lower the pump power threshold.
• Employed smooth tuning of the pump laser to achieve continuous frequency tuning of the OPO output across the phase-match bandwidth.
• Recorded the absorption spectrum of cesium vapor around the 1-micrometer wavelength region.

Main Results:

• Demonstrated a smoothly tunable, single-frequency continuous-wave OPO with a remarkably low pump power threshold of 30 mW.
• Confirmed that the doubly resonant nature and frequency-selective properties allowed tuning across the entire phase-match bandwidth without additional intracavity components.
• Successfully recorded the absorption spectrum of cesium vapor, validating the OPO's capability for high-resolution spectroscopic measurements.

Conclusions:

• The developed KTP-based doubly resonant OPO is a practical and efficient light source for high-resolution spectroscopy.
• Its low threshold and smooth, wide tunability make it suitable for various spectroscopic applications, including atomic vapor analysis.
• This work presents a significant advancement in developing compact and accessible OPO systems for scientific research.