Spectral Narrowing and Wavelength Tuning in Injection-Seeded Pulsed Optical Parametric Oscillator for Photoacoustic Methane Analyzer

We explored possibility to enhance spectroscopic capabilities of mid-IR optical parametric oscillators (OPOs). Gas analysis based on the principles of photoacoustic spectroscopy (PAS) [1] is known to be an efficient approach to measure concentration of certain gases (e.g., methane) in the atmosphere. Laser radiation source for PAS gas analyzer should provide high-energy pulsed output with narrow optical spectrum. There should be also possibility for fine tuning of its wavelength to a strong absorption line of the detected gas. Herein, we report an original high-energy pulsed OPO, in which the fan-out periodically poled lithium niobate (PPLN) and injection seeding technique were employed for spectral narrowing and fine wavelength tuning.