The invention relates to a retroreflector able to be placed in contact with an environment, comprising, by way of constituent material, a material enabling a parameter of said environment to be picked up, said material modifying the optical transmission properties of the retroreflector when said parameter is present, said retroreflector being able to receive an incident light beam via a first face and to reemit a light beam via said first face.

A wavelength-tunable etalon includes a pair of substrates, each comprising a reflection layer, an electrode, and an alignment layer on opposing surfaces of the pair of substrates; a first seal line configured to seal liquid crystal between the pair of substrates; and a second seal line configured to divide a space in which the liquid crystal is sealed into a main liquid crystal accommodating space configured to pass laser and a sub-liquid crystal accommodating space provided external of the main liquid crystal accommodating space. The first seal line comprises a sub inlet configured to fluidly communicate the main liquid crystal accommodating space with the sub-liquid crystal accommodating space.

A wavelength-tunable etalon includes a pair of substrates, each comprising a reflection layer, an electrode, and an alignment layer on opposing surfaces of the pair of substrates; a first seal line configured to seal liquid crystal between the pair of substrates; and a second seal line configured to divide a space in which the liquid crystal is sealed into a main liquid crystal accommodating space configured to pass laser and a sub-liquid crystal accommodating space provided external of the main liquid crystal accommodating space. The first seal line comprises a sub inlet configured to fluidly communicate the main liquid crystal accommodating space with the sub-liquid crystal accommodating space.

The invention relates to an electrically controlled interference colour filter comprising at least two transparent electrodes, at least one nematic liquid crystal layer and alignment layers for alignment of the liquid crystals. When an electrical field is applied the liquid crystals can be realigned and thus the transmission wavelength range of the interference colour filter can be shifted.

Tunable filter arrays include an array of liquid crystal (LC) tunable Fabry-Perot (FP) microcavities. The microcavities are defined by first and second reflectors and an LC layer situated between the reflectors. The tunable filter is secured to an image sensor array so that the LC tunable microcavities are coupled to respective photodetectors of the image sensor array. Patterned electrodes are situated about the LC layer to tune the microcavities.

A tunable band-stop filter, a method of driving a tunable band-stop filter and an electronic device are provided. The tunable band-stop filter includes a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate. The first substrate includes a wire structure on a first base substrate, the second substrate includes a common electrode on a second base substrate. The wire structure includes a first wire structure and a second wire structure. The first wire structure, the common electrode, and the liquid crystal layer between the first wire structure and the common electrode constitute a first phase modulation structure, and the second wire structure, the common electrode, and the liquid crystal layer between the second wire structure and the common electrode constitute a second phase modulation structure.

A wavelength-tunable etalon includes a pair of substrates, each comprising a reflection layer, an electrode, and an alignment layer on opposing surfaces of the pair of substrates; a first seal line configured to seal liquid crystal between the pair of substrates; and a second seal line configured to divide a space in which the liquid crystal is sealed into a main liquid crystal accommodating space configured to pass laser and a sub-liquid crystal accommodating space provided external of the main liquid crystal accommodating space. The first seal line comprises a sub inlet configured to fluidly communicate the main liquid crystal accommodating space with the sub-liquid crystal accommodating space.

A tunable band-stop filter, a method of driving a tunable band-stop filter and an electronic device are provided. The tunable band-stop filter includes a first substrate, a second substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate. The first substrate includes a wire structure on a first base substrate, the second substrate includes a common electrode on a second base substrate. The wire structure includes a first wire structure and a second wire structure. The first wire structure, the common electrode, and the liquid crystal layer between the first wire structure and the common electrode constitute a first phase modulation structure, and the second wire structure, the common electrode, and the liquid crystal layer between the second wire structure and the common electrode constitute a second phase modulation structure.

The present invention relates to a tuneable optical microcavity, characterised in that it comprises electrodes (12) on substrates (11), wherein the electrodes are comprised in the structure of dielectric or metal mirrors (13), or each of the electrodes has at least one dielectric or metal minor (13) on it, or the electrodes are semitransparent metal minors (13), wherein the mirrors are preferably located at a separation being a multiple of ½ lambda, where lambda is the central wavelength of the cavity mode, the cavity between the mirrors being filled with material (15) that changes the effective refractive index under the influence of external fields, preferably such as electric, magnetic field, thermal and mechanical stress.

The present invention relates to a method to tune a wavelength of a coherent light signal emitted by a tunable laser, the tunable laser comprising: a cavity, the cavity including: a gain medium, an optical tunable filter, a first and a second mirrors, one of which is partially reflective, wherein the optical tunable filter includes: a first and a second electrodes, a liquid crystal, the method comprising: applying a voltage difference between the first and second electrodes to apply an electric field to the liquid crystal; wherein applying a voltage difference includes: applying the voltage difference for at least a driving time interval lasting less than 1 μs; and varying the voltage difference applied between the first and second electrodes within the driving time interval so that a maximum applied voltage difference is reached and said maximum applied voltage is above 0.1 kV.