Continuous resonant four-wave mixing in double-Lambda level configurations of Na(2)

Area of Science:

• Atomic and Molecular Physics
• Nonlinear Optics
• Quantum Optics

Background:

• Resonant frequency mixing is a nonlinear optical process that generates new frequencies.
• Lasing without inversion (LWI) is a quantum optical phenomenon that allows gain without population inversion.
• Sodium dimer (Na2) molecules provide a suitable system for studying resonant nonlinear optical phenomena due to their accessible energy levels.

Purpose of the Study:

• To demonstrate efficient continuous resonant frequency mixing in Na2.
• To investigate the underlying mechanisms, including interference effects.
• To explore the implications for lasing without inversion.

Main Methods:

• Utilized a bichromatic field generated by an Ar(+)-laser-pumped Na2 Raman laser (488 nm, 525 nm).
• Employed a dye laser (655 nm) for resonant interaction with specific Na2 transitions (X(1)Σg+(υ=3, J=43) → B(1)Πu(6, 43) → X(1)Σg+(13, 43) → A(1)Σg+(24, 44)).
• Operated the experiment in a Na2 heat pipe and analyzed output power and parameter dependences.

Main Results:

• Achieved continuous resonant frequency mixing with an output beam at 599 nm.
• Observed an output power of up to 0.2 mW for specific input powers (200 mW, 25 mW, 400 mW).
• Measured parameter dependences suggest the significant influence of interference effects.

Conclusions:

• Demonstrated efficient continuous resonant frequency mixing in Na2, a key step towards LWI.
• Interference effects play a crucial role in the observed nonlinear optical phenomena.
• The findings contribute to the fundamental understanding and experimental realization of lasing without inversion.