A lasing device includes an active layer comprising a cholesteric liquid crystal material and a laser dye, and a liquid crystal cell including spaced apart substrates defining a cell gap in which the active layer is disposed. The substrates include electrodes arranged to bias the active layer into an oblique helicoidal (Ch.sub.OH) state. At least one substrate of the liquid crystal cell is optically transparent for a lasing wavelength range of the device.

Provided is a polymer which is capable of forming a liquid crystal alignment layer that combines an excellent alignment regulating force, high sensitivity with respect to polarized ultraviolet ray, and excellent durability. The polymer includes a side chain unit represented General Formula (I) and a side chain unit represented by General Formula (II), in which a polyamic acid or a polyimide is set as a main chain.

The present invention provides a polymerizable cholesteric liquid crystal composition containing: one or two or more polymerizable liquid crystal compounds (I) having two or more polymerizable functional groups in the molecule; a chiral compound (III); a polymerization initiator (IV); optionally a non-silicon compound (V) having a repeating unit; and optionally one or two or more polymerizable liquid crystal compounds (II) having one polymerizable functional group. An optically anisotropic body formed from a polymerizable liquid crystal composition according to the present invention is also provided.

The present invention provides a polymerizable cholesteric liquid crystal composition containing: one or two or more polymerizable liquid crystal compounds (I) having two or more polymerizable functional groups in the molecule; a chiral compound (III); a polymerization initiator (IV); optionally a non-silicon compound (V) having a repeating unit; and optionally one or two or more polymerizable liquid crystal compounds (II) having one polymerizable functional group. An optically anisotropic body formed from a polymerizable liquid crystal composition according to the present invention is also provided.

Disclosed is a method for preparing a solid-state helical photonic crystal structure. The method includes: mixing a nonreactive chiral dopant with a reactive nematic mesogen, followed by curing to form a helical cholesteric liquid crystal; and removing the chiral dopant from the cholesteric liquid crystal while maintaining the helical structure of the cholesteric liquid crystal, to form a solid-state helical liquid crystal.

Disclosed is a method for preparing a solid-state helical photonic crystal structure. The method includes: mixing a nonreactive chiral dopant with a reactive nematic mesogen, followed by curing to form a helical cholesteric liquid crystal; and removing the chiral dopant from the cholesteric liquid crystal while maintaining the helical structure of the cholesteric liquid crystal, to form a solid-state helical liquid crystal.

A low birefringence ferroelectric liquid crystal (FLC) mixture composed of at least two components shows birefringence in the range 0.05 to 0.14, which is suitable for the modern display and photonic devices. The cell gap can be tuned from 1.5 m to 4 m to reduces the fabrication complexity and chromatic distortion by electro-optical modulation. The FLC mixtures can be employed in a wide temperature range. The characteristics of the said FLC mixture can be tuned by tuning the concentration of the constituents of the mixture. The helical pitch of the FLC mixtures can be varied from 100 nm to 10 m. A smectic tilt angle can be varied between 17 to 45 and the spontaneous polarization can be tuned over a wide range to meet requirements of different electro-optical modes, and the FLC mixture is applicable for a wide variety of electro-optical effects.

A low birefringence ferroelectric liquid crystal (FLC) mixture composed of at least two components shows birefringence in the range 0.05 to 0.14, which is suitable for the modern display and photonic devices. The cell gap can be tuned from 1.5 m to 4 m to reduces the fabrication complexity and chromatic distortion by electro-optical modulation. The FLC mixtures can be employed in a wide temperature range. The characteristics of the said FLC mixture can be tuned by tuning the concentration of the constituents of the mixture. The helical pitch of the FLC mixtures can be varied from 100 nm to 10 m. A smectic tilt angle can be varied between 17 to 45 and the spontaneous polarization can be tuned over a wide range to meet requirements of different electro-optical modes, and the FLC mixture is applicable for a wide variety of electro-optical effects.

Shown is a compound represented by formula (1). For example, R.sup.1 is alkyl having 1 to 15 carbons; MES is a mesogen group having at least one ring; Sp.sup.1 is a single bond or alkylene having 1 to 10 carbons; M.sup.1 is methyl; and R.sup.2, M.sup.2 and M.sup.3 are hydrogen.

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A laminate includes at least one first reflective layer formed by immobilizing a liquid crystal phase in which a rotational direction of the helical axis is rightward, and at least one second reflective layer formed by immobilizing a liquid crystal phase in which the rotational direction of the helical axis is leftward, in which the laminate has a first transmission band in the wavelength range of 300 to 3,000 nm, the half-width of the first transmission band is 200 nm or less, an average transmittance in a wavelength range from a half-value wavelength A on the short wavelength side of the first transmission band to a half-value wavelength B on the long wavelength side of the first transmission band is 50% or more, and the average transmittance in the wavelength range of 100 nm from the half-value wavelength A to the short wavelength side and the average transmittance in the wavelength range of 100 nm from the half-value wavelength B to the long wavelength side are respectively less than 20%.