Tunable nano-phase polymer dispersed liquid crystal filter

A tuneable filter having a transmission-wavelength characteristic with at least one maximum or minimum comprising:

• a resonant cavity;
• a layer of nano phase polymer dispersed liquid crystal (PDLC) material contained within and forming part of said resonant cavity, wherein the PDLC material is polarisable by means of an applied electric field;
• at least one layer of dielectric material on each side of the PDLC material, said dielectric material having a refractive index different from that of the PDLC material;
• and
• electrodes across at least a portion of said PDLC material and a variable source of voltage applied to said electrodes to apply a variable electric field across the PDLC material,
• wherein variation of the electric field applied across the PDLC material gives rise to variation of the wavelengths at which the maximum or minimum occurs in the transmission-wavelength characteristic.

A tuneable filter having a transmission-wavelength characteristic with at least one maximum or minimum comprising:

• a stack of at least two phase matched resonant cavities;
• a layer of nano phase polymer dispersed liquid crystal (PDLC) material contained within and forming part of each of said resonant cavities, wherein the PDLC material is polarisable by means of an applied electric field,
• at least one layer of dielectric material on each side of the PDLC material, said dielectric material having a refractive index different from that of the PDLC material and
• means for applying a variable electric field across the PDLC material in each of said resonant cavities,
• wherein variation of the electric field applied across the PDLC material gives rise to variation of the wavelengths at which the maximum or minimum occurs in the transmission-wavelength characteristic.

A tuneable filter having a transmission-wavelength characteristic with at least one maximum or minimum comprising:

• a stack of at least two phase matched resonant cavities;
• a layer of nano phase polymer dispersed liquid crystal (PDLC) material contained within and forming part of each of said resonant cavities, wherein the PDLC material is polarisable by means of an applied electric field,
• at least one layer of dielectric material on each side of the PDLC material, said dielectric material having a refractive index different from that of the PDLC material and
• a source of variable electric field connected across the PDLC material in each of said resonant cavities,
• wherein variation of the electric field applied across the PDLC material gives rise to variation of the wavelengths at which the maximum or minimum occurs in the transmission-wavelength characteristic.

A tuneable filter having a transmission-wavelength characteristic with at least one maximum or minimum comprising:

• at least one resonant cavity;
• a plurality of layers of nano phase polymer dispersed liquid crystal (PDLC) material contained within and forming part of said resonant cavity, wherein the PDLC material is polarisable by means of an applied electric field,
• at least one layer of dielectric material on each side of the PDLC material, said dielectric material having a refractive index different from that of the PDLC material, and
• means for applying a variable electric field across the PDLC material, said means for applying comprising at least two substantially transparent electrode layers,
• wherein variation of the electric field applied across the PDLC material gives rise to variation of the wavelengths at which the maximum or minimum occurs in the transmission-wavelength characteristic.

A tuneable filter having a transmission-wavelength characteristic with at least one maximum or minimum comprising:

• at least one resonant cavity;
• at least one layer of nano phase polymer dispersed liquid crystal (PDLC) material contained within and forming part of said resonant cavity, wherein the PDLC material is polarisable by means of an applied electric field,
• at least two layers of dielectric material on each side of said at least one layer of PDLC material, said dielectric material having a refractive index different from that of the PDLC material, and
• means for applying a variable electric field across the PDLC material,
• wherein variation of the electric field applied across the PDLC material gives rise to variation of the wavelengths at which the maximum or minimum occurs in the transmission-wavelength characteristic.