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Frequency locking of a laser by injected atomic coherence.
Optics Letters
|September 18, 2009
Summary
Injected atomic coherence enables ring laser oscillation below threshold and without inversion, with frequency locked to the atomic line center. Mode locking becomes unstable with increased excitation.
Area of Science:
- Quantum optics
- Laser physics
Background:
- Ring lasers typically require population inversion for oscillation.
- Injected coherence can influence laser dynamics.
Purpose of the Study:
- Investigate the effect of injected atomic coherence on ring laser behavior.
- Determine conditions for laser oscillation below the conventional threshold.
Main Methods:
- Modeling a single-mode unidirectional ring laser with a two-level medium.
- Incorporating injected atomic coherence under phase-matching conditions.
- Analyzing laser gain and oscillation thresholds.
Main Results:
- Injected coherence directly enhances laser gain.
- Oscillation occurs below the usual threshold, even without population inversion.
- Laser frequency locks to the atomic line center.
- Mode locking is unstable at high excitation levels.
Conclusions:
- Injected coherence provides an alternative pathway for laser oscillation.
- This phenomenon offers potential for novel laser designs operating below threshold.
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