Advanced label-free biochemical sensors based on integrated optical waveguide gratings: theory, modeling, design and characterization

Sensors based on waveguide gratings have proved their suitability to high sensitivity bio-chemical sensing tasks. Application fields include medical diagnostics, pharmaceutical drug screening, environmental sensing and food quality control. Recent developments led to instruments, which excel in sensitivity and robustness. The present work introduces novel approaches for modeling such sensor devices. The methods are efficient, adapted to practical engineering tasks, and have short implementation and calculation times. The application of the different methods to the design and characterization of advanced waveguide grating sensors are presented. A first approach consists in enhancing a set of well-known methods to include the impact of birefringent materials and parasitic substrate reflections. The development of the methods is presented in detail, together with simulations showing parameter dependencies of practical relevance. As an example, a basic requirement in sensor design is maximum sensitivity to the measurand together with minimal sensitivity to parasitic effects, such as ambient temperature changes. The most important novelty described in the present work is the Local Interference Method (LIME). This method is a rapid and approximate calculation scheme for modeling the resonance line shape of non-trivial waveguide grating configurations. Its development was motivated by the lack of practical modeling methods for such structures. The successful application of the algorithm to a difficult analysis task of a non-uniform waveguide grating is presented. The benefits of the work are illustrated by the results obtained with enhanced sensor designs. Furthermore, an instrument is presented that was developed in the framework of this thesis, implementing some of the above-mentioned methods for the analysis of waveguide gratings in the production process.

Thèse de doctorat : Université de Neuchâtel : 2004 ; 1760