Rb-He excimer involved in four-wave mixing process to produce redshifted collimated blue light

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Physics and Photonics

Background:

• Four-wave mixing (FWM) is crucial for generating collimated light (CL) from alkali vapors.
• Broadening absorption linewidths is key to optimizing FWM efficiency.

Purpose of the Study:

• To investigate the use of high-pressure helium gas to broaden the absorption linewidth of rubidium (Rb) atoms.
• To achieve redshifted and asymmetric broadened collimated light (CL) around 420 nm.
• To demonstrate and elucidate the mechanism of Rb-He excimer participation in the FWM process.

Main Methods:

• Employing high-pressure helium gas with rubidium vapor.
• Utilizing an optical parametric oscillator (OPO) for tunable pump laser excitation.
• Performing two-photon excitation of the Rb-He mixture.
• Analyzing spectral and temporal data to identify excimer involvement.

Main Results:

• Achieved redshifted and asymmetric broadened collimated light (CL) around 420 nm.
• Demonstrated, for the first time, the participation of Rb-He excimers in the FWM process.
• Observed that peak CL intensity at ~420 nm is influenced by heating temperature and optical depth.

Conclusions:

• High-pressure buffer gas systems, specifically Rb-He, are effective for generating collimated blue light.
• Rb-He excimers play a significant role in the FWM process, influencing light characteristics.
• This research provides a foundation for optimizing alkali metal-buffer gas systems for efficient FWM-based light generation.