Enhancing Optical Up-Conversion Through Electrodynamic Coupling with Ancillary Chromophores

In lanthanide-based optical materials, control over the relevant operating characteristics–for example transmission wavelength, phase and quantum efficiency–is generally achieved through the modification of parameters such as dopant/host combination, chromophore concentration and lattice structure. An alternative avenue for the control of optical response is through the introduction of secondary, codoped chromophores. Here, such secondary centers act as mediators, commonly bridging the transfer of energy between primary absorbers of externally sourced optical input and other sites of frequency-converted emission. Utilizing theoretical models based on experimentally feasible, three-dimensional crystal lattice structures; a fully quantized theoretical framework provides insights into the locally modified mechanisms that can be implemented within such systems. This leads to a discussion of how such effects might be deployed to either enhance, or potentially diminish, the efficiency of frequency up-conversion

Chirality and magnetism: Free electron on an infinite helix, NCD, MCD,and magnetochiral dichroism

The free electron on a helix with periodic boundary conditions is undoubtedly one of the simplest quantum chemical models exhibiting both chirality and orbital angular momentum. Subjected to a light beam traveling parallel to the helix axis, the model exhibits natural circular dichroism and, assuming a lifting of the magnetic degeneracy by an external static magnetic field, also magnetic circular dichroism and magnetochiral dichroism. We believe that the model illustrates well the interplay of chirality and magnetism in a pure magnetic state, and that it could also be of interest in the study of the recently discovered chiral ferromagnets

Chirality and magnetism II: Free electron on an infinite helix, inverse Faraday effect and inverse magnetochiral effect

The interplay of chirality and magnetism is of fundamental physical interest. A free electron on a helix with periodic boundary conditions is possibly the simplest model exhibiting both chirality and orbital paramagnetism. In a previous report we have studied with this model the relation between natural circular, magnetic circular and magnetochiral dichroism. Here we extend our investigation to the second-order nonlinear optical phenomena designated as the inverse Faraday effect and as the inverse magnetochiral effect. Both effects manifest themselves as a radiation-induced time-independent magnetic field which lifts the magnetic degeneracy of the system. While the inverse Faraday effect is circular differential, the comparatively much weaker inverse magnetochiral effect is independent of the polarization of the incident radiation