Reflective LC devices including thin film metal grating
AssigneeLumentum Operations LLC
InventorsKeith Anderson, John Michael Miller, Hery Djie, Lu Tian
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Abstract
A sub-wavelength thin-film metal grating is placed inside a liquid crystal variable optical retarder at a selected distance from a reflective electrode to form a reflective half wave plate, thereby reducing polarization dependence of the optical retardation generated by the variable optical retarder. The approach enables to form within the device the reflective half wave plate that is suitably thin without modifying the reflective electrode of the device.
Claims20
A method for fabricating a liquid crystal (LC) device, the method comprising:
- providing a substrate comprising a first electrode having a flat top surface and an electrode passivation layer disposed over the flat top surface of the first electrode,
- the substrate comprising a reflective top face;
- depositing a spacer layer formed of a single optically transparent material, substantially transparent for light at a target wavelength, over the reflective top face of the substrate;
- forming, after depositing the spacer layer, a sub-wavelength metal grating over the spacer layer;
- depositing, after forming the sub-wavelength metal grating over the spacer layer, a grating cap layer over the sub-wavelength metal grating;
- disposing, after depositing the grating cap layer over the sub-wavelength metal grating, an LC layer over the grating cap layer;
- and
- disposing, after disposing the LC layer over the grating cap layer, a transparent second electrode over the LC layer in opposition to the first electrode such that the LC layer imparts a variable optical phase shift to light impinging on the transparent second electrode when a voltage is applied between the first electrode and the transparent second electrode.
A method for fabricating a liquid crystal (LC) device, the method comprising:
- depositing a spacer layer formed of a single optically transparent material, substantially transparent for light at a target wavelength, over a reflective top face of a substrate,
- the substrate comprising a first electrode having a flat top surface and an electrode passivation layer disposed over the flat top surface of the first electrode so as to form the reflective top face of the substrate, and
- the spacer layer being located between the first electrode and a sub-wavelength metal grating;
- forming, after depositing the spacer layer, the sub-wavelength metal grating over the spacer layer, the sub-wavelength metal grating comprising a plurality of parallel, spaced apart metal strips;
- depositing, after forming the sub-wavelength metal grating over the spacer layer, a grating cap layer over the sub-wavelength metal grating;
- disposing, after depositing the grating cap layer over the sub-wavelength metal grating, an LC layer, including a director, over the grating cap layer;
- and
- disposing, after disposing the LC layer over the grating cap layer, a transparent second electrode over the LC layer in opposition to the first electrode such that the LC layer imparts a variable optical phase shift to light impinging on the transparent second electrode when a voltage is applied between the first electrode and the transparent second electrode.
Dependencies are inferred from the claim text.