Multi-transversal mode pumping of narrow-bandwidth backward wave optical parametric oscillator.

Area of Science:

• Nonlinear Optics
• Laser Physics
• Spectroscopy

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• Backward wave OPOs (BWOPOs) offer unique advantages in spectral characteristics and efficiency.
• Developing high-energy, narrow-bandwidth sources is essential for applications like lidar.

Purpose of the Study:

• To present a stable, narrow-bandwidth BWOPO generating mJ-level output.
• To investigate the impact of pumping conditions on spectral properties.
• To demonstrate the tunability and amplification capabilities for advanced applications.

Main Methods:

• Utilized a single-longitudinal mode, Q-switched Nd:YAG laser for pumping.
• Employed a backward wave optical parametric oscillator (BWOPO) configuration.
• Integrated the BWOPO output with a periodically poled potassium titanyl phosphate (PPRKTP) optical parametric amplifier (OPA).

Main Results:

• Achieved a stable, narrow-bandwidth (274 MHz) BWOPO with mJ-level backward signal at 1885 nm and forward idler at 2495 nm.
• Demonstrated over 100 GHz continuous tuning via crystal temperature adjustment, highlighting thermal expansion effects.
• Showcased spectral broadening and nanosecond pulse generation under multi-transversal mode pumping.
• Amplified BWOPO output to 20 mJ using a single-stage PPRKTP OPA.

Conclusions:

• The developed BWOPO system provides a stable, tunable, high-energy source in the near- and mid-infrared.
• The combination of BWOPO and OPA offers a simple yet effective approach for high-energy parametric light generation.
• This technology holds significant promise for advancing long-range differential absorption lidar (DIAL) systems.