Voltage-tuned resonant reflectance optical filter for visible wavelengths fabricated by nanoreplica molding

Abstract

A guided-mode resonant filter incorporating an electro-optically tunable liquid crystal refractive index is demonstrated at a wavelength of 655nm and a tuning range of 4nm. Rigorous coupled wave analysis and finite difference time domain analysis are used to simulate the characteristics of the filter during liquid crystal reorientation. Tuning performance is demonstrated that is consistent with the device simulations. Tunable filters in the visible wavelength range that are inexpensively fabricated over large surface areas are expected to find applications in optical limiting and video display.

All-polymer photonic crystal slab sensor

“…In addition to providing means for novel optical elements, such as wavelength selective mirrors, polarizers [1], waveplates [2], tunable filters [3][4][5][6][7] and ultrabroadband mirrors [8], such resonant gratings have increasingly found their way into a myriad of different sensing applications, such as chemical and environmental sensing [9,10], label-free biosensing [11][12][13], cancer screening [14,15], photonic crystal enhanced microscopy [16] and three dimensional imaging [17]. These resonant gratings, referred to here as photonic crystal slabs (PCS) [18], but also known as guided mode resonance filters or reflectors [1,19] and photonic crystal resonant reflectors [20] in the literature, are essentially slab waveguides in which the high refractive index waveguide core is in some way periodically modulated, such as by refractive index or thickness, and surrounded by cladding media of lower refractive indices [1,18].…”

Effects of defect permittivity on resonant frequency and mode shape in the three-dimensional woodpile photonic crystal

“…One way is to incorporate a liquid crystal into the defect area of the PC and apply an electric field to the liquid crystal. 15,16 Another method is to use a material, such as NaNO 2 , which exhibits changes in its ferroelectric structure with changes in temperature. These ferroelectric changes yield a change in refractive index with temperature at optical wavelengths.…”

Optically tuned resonant optical reflectance filter

“…The results are not shown here but similar results were discussed in a previous publication. 18 The isotropic cis state of the particular azo-LC material used in this report is relatively stable. 22 By observing the PWV of a device over time, it was determined that 24 h was required for the azo-LC to relax back to its nematic trans state when left in a dark environment.…”

“…2-7 GMR filters can exhibit the same bandwidth and reflection efficiency as multilayer Bragg filters, but can be fabricated using a one-dimensional ͑1D͒ or two-dimensional periodic grating structure combined with a single high refractive index thin film deposition using either lithography 8,9 or plastic-based replica molding 10,11 to form the required subwavelength grating structure. Since the demonstration of the first static GMR filters, 12,13 efforts have been made to incorporate materials with variable refractive index that can be controlled either optically 14 or electrically [15][16][17][18][19] that can result in a filter with properties that are tunable. Applications for tunable filters include laser eye protection, optical limiting for sensor protection, 20 optical switching, video display, and optical memory, where selective opening or closing of an optical passband can be utilized.…”