High-resolution, broadly-tunable mid-IR spectroscopy using a continuous wave optical parametric oscillator

Area of Science:

• Optics and Photonics
• Spectroscopy
• Laser Physics

Background:

• Mid-infrared (mid-IR) light sources are crucial for various spectroscopic applications.
• Continuous tuning and mode-hop-free operation are desirable for high-resolution spectroscopy.
• Existing mid-IR sources often require manual adjustments and lack extensive tuning ranges.

Purpose of the Study:

• To design and automate a continuous wave, singly-resonant optical parametric oscillator (SRO-OPO) for mid-IR generation.
• To implement a tuning algorithm for hands-free, mode-hop-free tuning over a broad spectral range.
• To demonstrate the utility of the automated OPO for mid-IR gas-phase spectroscopy.

Main Methods:

• Design and construction of a singly-resonant optical parametric oscillator.
• Development of a hands-free control system and a tuning algorithm.
• Spectroscopic measurement of acetylene (C2H2) gas using the OPO.
• Comparison of experimental spectra with HITRAN 2016 simulations.

Main Results:

• Achieved hundreds of nanometers of continuous, effective-mode-hop-free tuning from 2190-4000 nm.
• Demonstrated the OPO's applicability to mid-IR spectroscopy.
• Obtained excellent agreement between experimental and simulated acetylene absorption spectra.
• Reported reduced uncertainty in spectral peak centers compared to simulations.

Conclusions:

• The automated mid-IR SRO-OPO provides a versatile and stable light source for spectroscopy.
• The implemented tuning algorithm enables robust, wide-range, mode-hop-free operation.
• This technology advances mid-IR spectroscopic capabilities, offering improved accuracy in spectral analysis.