A Coherent Raman Oscillator Pumped by a Frequency Comb
Igal Aharonovich, Avi Pe
Free induction decay is the coherent emission of light that follows the excitation of a medium by a short pulse. During the coherence time of the medium (T2), all atoms/molecules oscillate ’in unison’, forming a macroscopic dipole that emits light as a large coherent antenna, ’broadcasting’ information on the quantum state of the atoms/molecules and its dynamical evolution. We present an optical oscillator, where the coherent dipole emission from a dynamical wave-packet, is amplified beyond the lasing threshold. By placing a molecular medium in an optical cavity that is synchronously pumped by a frequency comb laser, emission from the excitation of one pump pulse can return to the medium with subsequent pump pulses, allowing stimulated amplification. When threshold is crossed, a broadband coherent oscillation is achieved, bearing information on the coherent wave-packet dynamics inside the medium. We analyze theoretically this coherent Raman oscillator and simulate thoroughly it’s dynamics under most realistic conditions for a model system of Alkali dimers (Li2,K2) in a hot gas cell (100−300 ◦ C), showing that the oscillation condition is well within reach. If realized, this coherent Raman oscillator can open avenues for precise measurement of vibrational dynamics in molecules.
•Mar 18, 2014•0 citations