Nonresonant random lasing from a dye-doped smectic A* scattering device

Abstract

Nonresonant random lasing from a dye-doped smectic A* scattering device is demonstrated. The field-induced scattering state of a low molar mass liquid crystal in the smectic A* phase is found to provide sufficient feedback to generate random lasing when a gain material, such as a fluorescent dye, is doped into the liquid crystal host. Furthermore, we found that the emission intensity of the random laser at a given excitation energy can be adjusted by altering the strength of the applied electric field so as to modify the scattering texture and consequently the transport mean free path. This change in the transport mean free path results in a change in the random lasing threshold. Large values for the transport mean free path, which indicate a weak scattering strength, result in large threshold values and vice-versa. Finally, we discuss the benefits of controlling the scattering strength with an applied electric field in terms of potential device applications.

Simple and functional photonic devices from printable liquid crystal lasers

“…[7][8][9] A further mode of lasing operation is the random laser. [10][11][12][13][14] In these lasers, localised optical micro-cavities can be formed in strongly scattering gain media giving enhancement of spontaneous light emission. 11,15 Polymer dispersed liquid crystals (PDLCs) are composite materials that are formed by the immiscibility between a liquid crystal and a polymeric matrix.…”