The authors present a review on the recent approaches proposed to implement transversal RF filters. Different tunable transversal filters consisting of wavelength tunable optical taps and those employing the tunability of dispersive devices are presented showing their high-performance characteristics. A comprehensive review of the fundamentals and a discussion on the main limitation of these st...

The simulation of optical resonance filters based on quarter-wave shifted waveguide gratings is described. Wavelet-based numerical homogenization is applied to the filters, and the properties of the homogenized operators and their solutions are investigated. A method is proposed for replicating periodical sub-structures in the homogenized operators, making it possible to model very large struct...

The chemistry, photostability and mechanism of action of ultraviolet filters are reviewed. The worldwide regulatory status of the 55 approved ultraviolet filters and their optical properties are documented. The photostabilty of butyl methoxydibenzoyl methane (avobenzone) is considered and methods to stabilize it in cosmetic formulations are presented.

Aberrations occur in multispectral cameras featuring filter wheels because of color filters with different optical properties being present in the ray path. In order to ensure an exact compensation of these aberrations, a mathematical model of the distortions has to be developed and its parameters have to be calculated using the measured data. Such a model already exists for optical filters pla...

This work has constructed a model for the theoretical analysis of generalized magneto-optical transmission (GMOT) filters for any relative angle between the light beam and the applied magnetic field. This model was experimentally validated and shows good agreement between the theoretical predictions and the experimental spectra. In addition, the value of examining magneto-optical filters for ar...

We present a simple and effective method for the postfabrication trimming of optical microresonators. We photobleach CLD-1 chromophores to tune the resonance wavelengths of polymer microring resonator optical notch filters. A maximum wavelength shift of -8.73 nm is observed. The resonators are fabricated with a soft-lithography molding technique and have an intrinsic Q value of 2.6 x 10(4) and ...

Interference filters have improved over the years. Sharp spectral edges (> 1 db/nm) reach high optical density (OD > 8) in a few nm. In-situ optical monitoring to within 0.1 % error enables these levels of performance. Due to limitations related to f-number and resolution bandwidth, post-deposition testing in typical spectrophotometers cannot reveal the quality of today’s filters. Laser based m...

We report on the design and fabrication of porous silicon based rugate filters. We have achieved narrow line-width, high reflectivity optical filters made entirely from silicon by continuously varying of the refractive index of Si and apodizing the index profile of the structure. 2005 Elsevier B.V. All rights reserved.