Photon echoes and related four-wave-mixing spectroscopies using phase-locked pulses

Abstract

The use of phase‐locked pulses in various spectroscopic techniques related to the third‐order polarizationP (3) is analyzed. Using correlation function expressions for the nonlinear response function, we clarify the interrelationship among several photon echo, pump–probe, and spontaneous light emission techniques, without alluding to any specific model for the material system. By combining phase‐locked pulses and heterodyne detection it becomes possible to probe separately the real and imaginary parts of the nonlinear response function. Combining two phase‐locked pulse excitation with time‐resolved detection of the spontaneous light emission allows direct separation of the Raman and fluorescence contributions.