High-speed multi-THz-range mode-hop-free tunable mid-IR laser spectrometer.

Area of Science:

• Optics and Photonics
• Spectroscopy
• Materials Science

Background:

• Mid-infrared (mid-IR) laser sources are crucial for high-resolution molecular spectroscopy.
• Achieving wide tunability and rapid, mode-hop-free (MHF) operation in mid-IR lasers remains a challenge.
• Optical parametric oscillators (OPOs) offer a versatile platform for generating tunable mid-IR radiation.

Purpose of the Study:

• To develop a broadly and rapidly tunable MHF mid-IR laser source.
• To demonstrate the transfer of tuning capabilities from a pump laser to an OPO idler wave.
• To showcase the application of this laser system in high-resolution Doppler spectroscopy.

Main Methods:

• Utilized a singly resonant optical parametric oscillator (SRO) based on 5%-MgO:LiNbO(3).
• Employed a broadly MHF tunable extended-cavity diode laser (ECDL) as the pump source.
• Leveraged quasi-phase-matching in the SRO for efficient wavelength conversion.

Main Results:

• Achieved a widely tunable (2.25 THz or 75 cm(-1)) and rapidly (4.5 THz/s) MHF mid-IR laser source at approximately 3.3 μm.
• Demonstrated efficient transfer of the pump laser's broad and rapid MHF tuning to the SRO idler wave.
• Successfully performed fast and broadband high-resolution Doppler spectroscopy of the CH(4) ν(3) band.

Conclusions:

• The developed mid-IR laser source provides a powerful tool for fast, high-resolution spectroscopic measurements.
• The system's broad and rapid MHF tunability is advantageous for analyzing molecular absorption bands.
• This technology has significant potential for applications in gas sensing and molecular analysis.