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Continuous-wave mirrorless lasing at 2.21 μm in sodium vapors
Optics Letters
|November 2, 2018
Summary
Researchers achieved continuous-wave (cw) laser emission at 2.21 μm in sodium (Na) vapor using low laser power. This mirrorless lasing is magnetic field and polarization dependent, offering potential for remote sensing applications.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Laser Physics
- Quantum Optics
Background:
- Population inversion is crucial for laser operation.
- Sodium vapor offers unique atomic transitions for light generation.
- Continuous-wave (cw) emission requires stable excitation and gain conditions.
Purpose of the Study:
- To demonstrate backward-directed cw emission at 2.21 μm from two-photon excited sodium vapor.
- To investigate the power and atom-number-density thresholds for this specific laser emission.
- To explore the potential applications of this novel laser source, including remote magnetometry and atmospheric sensing.
Main Methods:
- Two-photon excitation of sodium (Na) vapor using resonant laser light at 589 nm and 569 nm.
- Generation of population inversion on the 4P3/2-4S1/2 transition.
- Characterization of lasing properties, including power thresholds, atom density requirements, and beam divergence.
- Investigation of magnetic field and polarization dependence of the mirrorless laser emission.
Main Results:
- Demonstrated backward-directed cw emission at 2.21 μm.
- Lasing achieved at sub-10 mW total applied laser power.
- Observed beam divergence of 6 mrad, primarily determined by the gain region's aspect ratio.
- Confirmed magnetic field and polarization dependence of the mirrorless 2.21 μm lasing.
Conclusions:
- Successful generation of 2.21 μm cw laser emission in Na vapor via two-photon excitation.
- Low power requirements and mirrorless operation make this a potentially practical laser source.
- The observed magnetic field and polarization dependence suggest utility in remote magnetometry.
- Findings provide insights for developing directional return signals from mesospheric sodium atoms.
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