Abstract
We have found that an intense shot-noise-limited laser beam tuned near the 4 2S1/24 2P3/2 potassium resonance transition acquires excess noise after passing through an atomic-potassium vapor cell. The noise is maximum for laser detunings of approximately ±1 GHz and falls to nearly the shot-noise limit for detunings greater than ±3 GHz. We describe the production of this noise in terms of a forward four-wave mixing process involving the laser field and its side modes, which are initially in the vacuum state. We present a fully quantum-mechanical theory of forward four-wave mixing in a system of two-level atoms and use it to predict the noise properties of the transmitted laser beam. The predictions of this theory are in good agreement with the experimental data.
Original language | English |
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Pages (from-to) | 4152-4159 |
Number of pages | 8 |
Journal | Physical Review A |
Volume | 51 |
Issue number | 5 |
DOIs | |
State | Published - Jan 1 1995 |