A new approach based on the use of cholesteric liquid crystals (CLCs) and dye-doped light-sensitive chiral dopants was employed to create lasing materials with reversible tuning and switching. The lasing wavelength of optically-pumped dye-doped cholesteric liquid crystals (CLCs) is shifted by irradiation with UV light. The shift depends on the UV light exposure. Lasing is switched off at high levels of UV light irradiation. A qualitative model describing different lasing regimes is proposed.

Chiral hydrogen-bonded polymer films that respond to the presence of some amino acids (arginine, lysine, histidine) in water by changing the color and shifting the wavelengths of the selective reflection band (SRB) were synthesized and studied. The kinetics of the film's response depends on the concentration of donor/acceptor groups in the polymer matrix. A higher concentration of hydrogen-bonded groups results in a faster shift of the SRB and color changes. This effect is explained in terms of structural changes and the breakage of hydrogen bonds that occurs between the components of a cholesteric polymer, immersed in various aqueous solutions of amino acids. Optical pumping of cholesteric films doped with laser dyes leads to lasing. The changes in the selective reflection induced by amino acids in water solutions result in a shift of the lasing wavelength.

Cholesteric liquid crystals (CLC), polymer stabilized cholesteric liquid crystals (PSCLC), and polymer dispersed cholesteric liquid crystals (PDCLC) are promising dye-doped optically pumped lasing materials with an inherent photonic band gap structure. At low polymer concentrations, lasing from PSCLC occurs in modes near the edge of the selective reflection band. Electric field applied to the samples sandwiched between conducting glasses enhances PSCLC lasing emission. Lasing behavior changes dramatically at higher polymer concentrations in PDCLCs:  numerous lasing peaks appear on the top of the emission band. New effects are explained in terms of lasing in photonic defect modes and photonic band gap modes.