An integrated electromagnetic, molecular and lasing model for liquid crystal laser optimization

Dye-doped chiral nematic liquid crystals have self-organizing optical cavities enabling low cost, micro-scale photonic band-edge lasers, with a broad wavelength tuneability throughout the visible spectrum [1]. Liquid crystal (LC) lasers have prospective applications in imaging and sensing where a precise and customizable wavelength is required [2]. However, factors such as output stability, maximum average power and repetition rate, currently limit laser performance and possible commercialization. Some of these detrimental effects are temporary and reversible in nature (fatigue mechanisms), such as thermal build-up, triplet state excitation, or optically-induced reorientation from the pump laser [1]. Other effects may be more permanent, such as photobleaching of the dye at extreme input powers [1]. However detailed analysis and quantification of these different effects has not been thoroughly investigated.
We present the latest update on a comprehensive LC laser simulation, comprising of three linked models (Figure 1), to investigate the above phenomena. Pump propagation through the LC is simulated using FDTD method solving Maxwell’s equations. Landau-de Gennes free energy minimization (including Beris-Edward model) is used to simulate LC alignment [3]. Finally, lasing output is predicted using rate equations. This approach will provide better understanding of the relative contributions of fatigue mechanisms in LC lasers, enabling optimization of device architecture and pump parameters to maximize laser stability and output power.