The field of surface nanostructuring is growing rapidly with the need to search for more advanced fabrication solutions. The major challenge is the lack of appropriate combination of time/cost efficient techniques and medium possessing the advantages of both flexibility and tunable optical properties. Here we demonstrate direct-write femtosecond laser nanostructuring of indium–tin-oxide thin film where the deep-subwavelength ripples with periodicity of down to 120 nm are realized originating the form birefringence (|Δn| ≈ 0.2), which is 2 orders of magnitude higher than the commonly observed in uniaxial crystals or femtosecond laser nanostructured fused quartz. The demonstrated nanoripples with its continuously controlled space-variant orientation lead to the high density two-dimensional printing of flat optical elements. The technique can be extended to any highly transparent films that support laser-induced periodic surface structures, and can be effectively exploited for the integration of polarization sensitive modifications into multidimensional optical data storage.

Electrodes with higher transparency that can also align liquid crystals (LCs) are of high importance for improved costs and energy consumption of LC displays. Here we demonstrate for the first time alignment of liquid crystals on femtosecond laser nanostructured indium tin oxide (ITO) coated glass exhibiting also higher transparency due to the less interface reflections. The nano paterns were created by fs laser directlly on ITO films without any additional spin coating materials or lithography procces. Nine regions of laser-induced nanostructures were fabricated with different alignment orientations and various pulse energy levels on top of the ITO. The device interfacial anchoring energy was found to be 1.063 × 10 −6 2 ⁄ , comparable to the anchoring energy of nematic LC on photosensitive polymers. The device exhibits contrast of 30:1 and relaxation time of 330ms expected for thick LC devices. The measured transparency of the LC device with two ITO nanograting substrates is 10% higher than the uniform ITO film based LC devices. The alignment methodology presented here paves the way for improved LC displays and new structured LC photonic devices.

Combination of InGaAs/InP heterojunction photodetector with nematic liquid crystal (LC) as the electro-optic modulating material for optically addressed spatial light modulator for short wavelength infra-red (SWIR) to visible light image conversion was designed, fabricated, and tested. The photodetector layer is composed of 640 × 512 photodiodes array based on heterojunction InP/InGaAs having 15 μm pitch on InP substrate and with backside illumination architecture. The photodiodes exhibit extremely low, dark current at room temperature, with optimum photo-response in the SWIR region. The photocurrent generated in the heterojunction, due to the SWIR photons absorption, is drifted to the surface of the InP, thus modulating the electric field distribution which modifies the orientation of the LC molecules. This device can be attractive for SWIR to visible image upconversion, such as for uncooled night vision goggles under low ambient light conditions.

No abstract

A tunable extended depth of field (EDOF) imaging is presented using temporal multiplexing and a low-cost eight-ring, annular liquid crystal spatial light modulator. By changing between different phase profiles in the pupil plane of a lens we perform several levels of EDOF. Using these levels as a "database" it is shown by temporal multiplexing how to decompose tunable levels of EDOF.