Ultrafast Optical Signal Processing with Bragg Structures

The phase, amplitude, speed, and polarization, in addition to many other properties of light, can be modulated by photonic Bragg structures. In conjunction with nonlinearity and quantum effects, a variety of ensuing micro- or nano-photonic applications can be realized. This paper reviews various optical phenomena in several exemplary 1D Bragg gratings. Important examples are resonantly absorbing photonic structures, chirped Bragg grating, and cholesteric liquid crystals; their unique operation capabilities and key issues are considered in detail. These Bragg structures are expected to be used in wide-spread applications involving light field modulations, especially in the rapidly advancing field of ultrafast optical signal processing.Comment: To be published in a special issue of journal Applied Sciences, on the topic of Guided-Wave Optic

Organizzatrice e Chairman della Focus Session "Photosensitive Materials and Nano-structures for Optical Switching, Sensing and Processing Applications" al congresso PIERS 2019 Xiamen - PhotonIcs & Electromagnetics Research Symposium

Session's Information: “Photosensitive Materials and Nano-structures for Optical Switching, Sensing and Processing Applications” presents a forum for presentation of current state-of-the-arts development in optical and photonic material systems, electro-optical and all-optical phenomena for application in molecular-, nano- and bio-photonics, nonlinear- and electro-optics, communications, sensing integrated photonics. Materials of interest that possess extraordinary or unique characteristics include, but are not limited to, optofludics, bio-, molecular- and nano-structures, metamaterials and metasurfaces, photonic crystals, liquid crystals and soft matters

Passive Temperature Stabilization of Silicon Photonic Devices Using Liquid Crystals

In this work we explore the negative thermo-optic properties of liquid crystal claddings for passive temperature stabilization of silicon photonic integrated circuits. Photonic circuits are playing an increasing role in communications and computing, but they suffer from temperature dependent performance variation. Most existing techniques aimed at compensation of thermal effects rely on power hungry Joule heating. We show that integrating a liquid crystal cladding helps to minimize the effects of a temperature dependent drift. The advantage of liquid crystals lies in their high negative thermo-optic coefficients in addition to low absorption at the infrared wavelengths

Electrically tunable, optically induced dynamic and permanent gratings in dye-doped liquid crystals

We report on further experimental studies of the ac field response of transient and permanent gratings written with visible light in both planar and homeotropic, dye-doped liquid crystal cells. It is found that the diffraction efficiency of these gratings can be controlled by the applied ac field. High ac frequencies can switch off diffraction completely in both permanent and transient gratings. The response time to the applied electric field is shown to be in the range of milliseconds. Permanent gratings persist for months and, when heated above the liquid crystal phase transition temperature, they can be only partially erased. Furthermore, on cooling the diffraction efficiency can be restored, indicating a strong anchoring at the boundaries of the cel

Nonlinear optics and optical physics

viii, 481 p. : ill. ; 23 cm

Nonlinear optics and optical physics

viii, 481 p. : ill. ; 23 cm

Liquid crystal clad near-infrared metamaterials with tunable negative-zero-positive refractive indices

Near-infrared metamaterials that possess a reconfigurable index of refraction from negative through zero to positive values are presented. Reconfigurability is achieved by cladding thin layers of liquid crystal both as a superstrate and a substrate on an established negative-index metamaterial, and adjusting the permittivity of the liquid crystal. Numerical results show that the index of refraction for the proposed structure can be changed over the range from -1 to +1.8 by tuning the liquid crystal permittivity from 2 to 6 at a wavelength of 1.4 mu m

Tunable optical negative-index metamaterials employing anisotropic liquid crystals

A full-wave analysis technique based on the finite element-boundary integral method is developed and used to rigorously treat the scattering from periodically structured metamaterials incorporating anisotropic liquid crystals (LCs) and dispersive materials. Reconfiguration of the negative-index metamaterials is achieved by controlling the magnetic resonance via tuning permittivity of the embedded anisotropic LCs. Numerical results show that the refractive index of the metamaterials can be reconfigured by tuning the director orientation of anisotropic LCs or by using temperature-dependent LCs. The design configurations and their characteristics in the near- and the mid-infrared ranges are presented