LOCALIZED OPTICAL MODES IN PHOTONIC LIQUID CRYSTALS: OPTIONS FOR DFB LASING ENHANCEMENT AND MORE

A brief survey of the recent experimental and theoretical results on the low threshold distributed feedback (DFB) lasing in chiral liquid crystals (CLC) as well as new original theoretical results in the field are presented. The main attention is paid to the analytic approach in the theory of the DFB lasing in CLC based on the exact solutions of the boundary problems for light propagating along the helical axis in CLC layers [1]. Properties of the eigen edge (EM) and defect (DM) modes are investigated. The dispersion equations for EM and DM are found and the expressions determining the decay rate for these modes are presented. Lasing thresholds at frequencies corresponding to the spatially localized “stop band edge lasing modes ” and “defect modes ” in CLC are studied and it is shown that EM and DM present options for a further reduction of the lasimg thresholds. It is demonstrated that the analytic approach reproduces all features of the DFB lasing in CLC obtained by the traditional numerical approach [2] and, more over, allows to reveal some qualitative effects escaped from the researchers employing th