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This chapter gives an overview of the current challenges encountered in implementing devices based on high index contrast microphotonic waveguides, along with some new applications. An input coupler based on graded index (GRIN) waveguides is described. Theoretical and experimental results on using of cladding stress to eliminate the polarization dependence in SOI waveguide devices are reviewed. Recent work on output coupling of data on many output waveguides using waveguide to free space coupler array is also described. Design rules are presented for increasing bandwidth and resolution of integrated waveguide microspectrometers, to address applications in spectroscopic sensing and analysis. Finally, the potential for high index contrast microphotonic waveguides in evanescent field sensing is explored.

Optical microcavities trap light in compact volumes by the mechanisms of almost total internal reflection or distributed Bragg reflection, enable light amplification, and select out specific (resonant) frequencies of light that can be emitted or coupled into optical guides, and lower the thresholds of lasing. Such resonators have radii from 1 to 100 μm and can be fabricated in a wide range of materials. Devices based on optical resonators are essential for cavity-quantum-electro-dynamic experiments, frequency stabilization, optical filtering and switching, light generation, biosensing, and nonlinear optics.

choice of methods suitable for modeling high-refractive-index photonic waveguide structures is reviewed. Special attention is paid to methods based on mode matching. Basics of the transfer matrix mode solvers for multilayer structures, the (two-dimensional) bidirectional mode expansion and propagation method, and the film mode matching methods for straight and bent waveguides and circular microresonators with two-dimensional cross-sections are described in some detail.

plasmon resonance (SPR) biosensors show vast potential for detection of chemical and biological analytes in numerous important areas. This chapter discusses the underlying principles and configurations of SPR biosensors and reviews applications of SPR biosensor technology in food safety.

The present article reviews three different optical biosensing mechanisms that can be implemented in a multibiosensor technology platform: surface plasmon resonance, magnetooptical surface plasmon resonance and optoelectronic biosensing (evanescent wave detection) using integrated Mach-Zehnder interferometer devices. In the last case, the use of standard silicon microelectronics technology opens the possibility for integration of optical, fluidics based and electrical functions within a single optical sensing circuit leading to a complete lab-on-a-chip design solution. All three mechanisms can be efficiently used as an early warning system for biological and/or chemical warfare.

A simple numerical method for direct solving Maxwell's equations in the frequency domain is described. The method is applied to the modelling of onedimensional nonlinear periodic structures.

Investigation of spatiotemporal dynamics of optical pulse in step-index planar waveguide with Kerr nonlinearity is presented which is based on numerical solution of a (2D+T) wave equation for slowly varying amplitude of the total field. Effect of emission of radiation field that is specific for open dielectric waveguides is taken into account. This emission can be observed, first, as a result of light beam propagation through waveguide junctions, and second, due to some effects that vary the temporal distribution of an ultra-short optical pulse propagating in a regular nonlinear waveguide. Two types of junctions in weakly-guiding planar waveguides are under consideration: both waveguides have the same width and refractive index profile but possess different nonlinear properties, and both waveguides have the same refractive index profile and nonlinearity but their widths are different. In the quasi-static approximation, the problem of optical pulse propagation through the junctions is reduced to the solution of a 2D equation for the pulse envelope with time coordinate given as a parameter. Spatial transformations of the stationary components of the pulse behind the junctions are studied in detail depending on their power and waveguide width. The approach is based on general methods of the theory of Hamiltonian dynamical systems and consists of the following steps: (i) finding the set of stationary nonlinear modes, (ii) investigation of power-dispersion diagrams, and (iii) investigation of global dynamics. Transmittance versus power dependencies demonstrate the applicability of the junctions for pulse shaping and power controlling. In the case of ultrashort optical pulses, self-steepening effect and second-order group velocity dispersion effect are shown to prevent formation of stable spatiotemporal pulse distribution owing to the emission of radiation field outside the guiding region.

We investigate efficient frequency-doubling of low energy femtosecond pulses in bulk and waveguide nonlinear crystals, thereby demonstrating how to achieve a compact and portable ultrafast blue light source. Using a femtosecond Cr:LiSAF laser (fundamental wavelength 860 nm), we examine the relative merits of the process of second harmonic generation (SHG) using bulk potassium niobate, bulk aperiodically-poled KTP, periodically-poled and aperiodically-poled KTP waveguide crystals. While SHG conversion efficiencies up to 37% were achieved using the waveguides, non-traditional strong focusing in the bulk samples yielded efficiencies of 30%. We have developed several theoretical models to accurately describe the temporal and spectral properties of the generated blue light, as well as the observed saturation behavior of the conversion process in the waveguide structures.

This paper summarizes the results of our systematic study of PE and APE planar waveguides in LiNbO and LiTaO. We focused on the optical and structural characterization of PE layers formed on Z-cut substrates. The refractive index change was measured and the propagation losses were estimated. Raman spectroscopy was used as a method providing direct information about the phonon spectrum. The latter was related to the structure and the properties of the protonated waveguides.

A new diffractive device for light coupling between a planar optical waveguide and free space is proposed. The device utilizes a second order waveguide grating to diffract the fundamental waveguide mode into two free propagating beams and a sub-wavelength grating (SWG) mirror to combine the two free propagating beams into a single beam. The Finite Difference Time Domain (FDTD) simulations show that the SWG mirror improves the coupling efficiency of the waveguide fundamental mode into the single out-coupled beam from about 30 % to 92 %. A high efficiency (>80 %) is predicted for a broad wavelength range of 1520 - 1600 nm. The proposed device is compact (~ 80m in length), it eliminates the need for blazing the waveguide grating, and it is simple to fabricate using standard CMOS processes.