Abstract

Transient four-wave mixing techniques have been developed in the past several years for the investigation of ultrafast dephasing of electronic transitions in condensed matter [1,2]. These experiments involve self-diffraction of two noncollinear pulses from an optically induced absorption grating. We have recently reported an improved scheme utilizing three separate input pulses [3]. Similar three pulse transient grating experiments [4] can be used to study processes such as spatial diffusion, orientational relaxation and excited state relaxation; but the applicability to dephasing studies had not been previously recognized. Compared to the two pulse scattering, our three pulse experiment provides several important advantages, including resolution below the pulse width, clear demarcation between homogeneous and inhomogeneous broadening, and automatic separation of energy relaxation (T₁) effects from the phase relaxation (T₂) effects. In this paper we will first describe the three pulse scattering theoretically and then present new experimental data taken with a colliding-pulse-modelocked (CPM) ring dye laser [5].

© 1984 Optical Society of America