From Laser Induced Line Narrowing To Electromagnetically Induced Transparency in a Doppler-Broadened System
Ali Javan, Olga A. Kocharovskaya, Hwang Lee, Marlan O. Scully
Abstract
Laser induced line narrowing effect in Doppler broadened systems was discovered thirty years ago. This effect can also be applied to recent experimental studies in high resolution spectroscopy or high precision measurements based on Electromagnetically Induced Transparency (EIT). In this report we derive an analytic expression for the linewidth of EIT resonance in a Doppler broadened system. It is shown here that the EIT linewidth is proportional to the Rabi frequency of the driving field and is independent of the Doppler width in a limiting case. This recovers the result found in the laser induced line narrowing effect by Feld and Javan. In the other limit, we recovers the usual power broadening case where the EIT linewidth is proportional to the intensity of the driving field and inversely proportional to the Doppler width.