Effects of Injected Atomic Coherence on Multiwave Mixing.
Abstract
Discussion begins with a brief account of atomic levelpumping and reasons why atomic coherence is typically not considered in cw work on optical interactions. This dissertation is divided into four parts: semiclassical treatments of onephoton electric dipole atomfield single mode interactions and multimode interactions, and corresponding treatments for the twophoton interaction. We present the effects of injected atomic coherence on the polarization of the medium, the slowly varying envelope wave equation, the single and multiwave mixing coefficients, and weak field propagation in a homogeneously broadened twolevel medium. Spatial and temporal phase matching of the injected coherence to a field mode is crucial throughout, since the field may not be able to remain in phase with the induced and injected polarizations. Onephoton injected coherence contributes directly to the polarization at the atomic resonance frequency. The perfectly phasematched case leads to a linear superposition of an exponentially decaying field (Beer's law) and a constant field driven by the injected coherence. The interaction of an injected coherence with a detuned field produces frequencysymmetric sidebands about the pump field polarization. The sideband spacing equals the atomfield detuning. To probe the injected coherence we inject a weak resonant field. The resulting threewave mixing leads to multiwave mixing coefficients that are unaffected to firstorder in the weak sidemodes, but the injected coherence adds inhomogeneous terms to the coupledmode equations. For both single and multimode interactions the injected coherence does not affect the exponential growth/decay of the sidemodes, but it supports a weak field that may propagate if properly phase matched. For twophoton media the injected coherence requires at least one field interaction in order to produce a polarization, which then appears in the single and multiwave mixing coefficients. The exponential growth/decay rate is modified by the injected coherence. For a centrallytuned pump the injected coherence contributes the standard multiwave mixing terms as well as additional effects. Fourwave mixing is discussed as a means of relaxing the spatial phase matching constraint on the injected coherence.
 Publication:

Ph.D. Thesis
 Pub Date:
 1989
 Bibcode:
 1989PhDT........93C
 Keywords:

 Physics: Optics; Physics: Atomic