Optical signal processing using nonlinear periodic structures.
Published: 2003
Language: eng
Number of pages: 247
Description: This work advances the field of optical signal processing using nonlinear periodic structures. A novel approach to all-optical signal processing using nonlinear periodic structures is proposed. The nonlinear response of various materials is measured, and nonlinear periodic structures are fabricated and characterized.This work presents an analytical and numerical study of a stable all-optical limiter that clamps the output level below a design-specific limiting intensity. The introduction of disorder is predicted through theory to result in widening of the nonlinear stopband, localization of light, and formation of stationary gap solitons. It is shown through development and solution of a model that the incorporation of a built-in linear out-of-phase grating into the index-matched limiting structures can enable signal processing functions of hard-limiting, analog-to-digital conversion, and logic gating. A comprehensive theory of intensity-domain optical stability in nonlinear periodic structures is derived and conditions for multistability are presented. The propagation of pulses in the structures proposed is analyzed and effects of pulse intensity limiting and pulse compression are predicted.The resonant, ultrafast, and thermal nonlinear properties of inorganic crystalline semiconductor, organic, and nanocrystal materials are examined while seeking to maximize the strength of the refractive nonlinear response and associated figures of merit. Nonlinear index changes of record magnitude of -0.14 with figures of merit of 1.38 are found for InAlGaAs/InGaAs semiconductor multi-quantum-wells under the illumination at a wavelength of 1.5 mum and a fluence of 116 muJ/cm2. Resonant nonlinear response is demonstrated in strongly-confined semiconductor PbS nanocrystals in the spectral region of 1150 to 1600 nm.The theoretical and experimental accomplishments of this work expand the field of stable and multistable optical signal processing functionality of nonlinear periodic structures; and map out future directions for enhancing the functional diversity and performance of elements required for optical networks.Nonlinear periodic signal processing elements are designed, fabricated, and analyzed. One dimensional semiconductor elements are shown to yield fluence-dependent transfer characteristics due to the interplay of the nonlinear Bragg refraction and nonlinear absorption. A photonic stopband is experimentally demonstrated to emerge in the vicinity of the wavelength of 1.5 mum at fluences below 320 muJ/cm2. Three-dimensional organic colloidal crystals are proven to exhibit a nonlinear shift in the position of the photonic stopband and a decrease in the reflectivity in the 530 to 570 nm spectral region.
Notes: Adviser: Edward Sargent.

Thesis (Ph.D.)--University of Toronto, 2003.

Electronic version licensed for access by U. of T. users.

Source: Dissertation Abstracts International, Volume: 65-05, Section: B, page: 2534.