Dispersive kinetic processes, optical linewidths and dephasing in amorphous solids

Abstract

A theory which describes the dispersive behavior associated with (i) nonphotochemical hole growth (or photochemical hole growth with a distribution of photoproduct states) and (ii) spontaneous hole filling is developed and applied to existing experimental data. For certain systems, the hole growth data demand that hole filling during the burn (HFDB) be considered. The relationship of this filling to the recently discovered phenomenon of laser-induced hole filling (LIHF) is discussed. The above theory is based on the TLS model, with both intrinsic and extrinsic TLS (TLS int, TLS ext) taken into account. The TLS ext represent the subset of bistable configurations which interact strongly with or are created by the impurity. The two types of TLS are characterized by markedly different distribution function parameters. Finally, the question of whether holewidths can be used to provide the optical dephasing time is addressed. A mechanism for spectral diffusion (broadening) of holes due to slow (>T 1) TLS relaxation processes is proposed. Conditions under which the temperature power laws for optical dephasing and “slow” spectral diffusion may be the same are defined.