High-pulse-energy and high-efficiency 1.9  µm Raman laser

Area of Science:

• Laser Physics
• Nonlinear Optics
• Quantum Electronics

Background:

• Stimulated Raman scattering (SRS) is a key nonlinear optical process for generating new laser wavelengths.
• Efficient generation of mid-infrared lasers is crucial for various spectroscopic and remote sensing applications.
• Gas-based Raman lasers offer advantages in tunability and scalability.

Purpose of the Study:

• To efficiently generate a 1.9 µm laser using stimulated Raman scattering in pressurized hydrogen.
• To optimize parameters for maximizing Raman laser energy and photon conversion efficiency (PCE).
• To investigate the impact of pumping beam shape on laser performance.

Main Methods:

• Utilized a 1064 nm pulsed laser to pump pressurized hydrogen gas within a multi-pass cell.
• Optimized hydrogen pressure, focusing conditions (f=1000 mm cylindrical lens), and multi-pass configuration (five passes).
• Employed simulations to evaluate the effect of a square pumped beam on laser output.

Main Results:

• Achieved 199.8 mJ of Raman laser output at 0.75 MPa hydrogen pressure.
• Obtained a maximum photon conversion efficiency (PCE) of 82.7% and energy conversion efficiency of 46.2%.
• Demonstrated a maximum PCE of 86.5% at 1 MPa and excellent beam quality (Mx²=2.6, My²=2.4).

Conclusions:

• Parametric optimization of pressure, focusing, and multi-pass configuration is highly effective for gas-phase Raman lasers.
• The study confirms the potential for high-efficiency, high-beam-quality laser generation in pressurized hydrogen.
• Simulations suggest that a square pumped beam can further enhance Raman laser energy and PCE.