Emmanuel Drouard

Highly Integrated Optical 4

In this paper, we present the design, fabrication, and characterization of a highly integrated optical 4 x 4 crossbar based on microring resonator add-drop filters. The designed crossbar structure, as small as 50 mum x 50 mum, has been fabricated in CMOS compatible silicon on insulator technology. Finally, experimental results proving the proper operation of the fabricated crossbar structures are discussed.

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Measurements of ∂n/∂T of thin films by the m-lines technique are presented. The importance of the substrate material is shown. An example of the wavelength shift of an optical thin-film filter with temperature is studied both theoretically and experimentally. The theoretical wavelength shift of a dense wavelength-division multiplexing filter is discussed.

4 Crossbar in Silicon-on-Insulator Technology

A low loss refractive waveguided mode can be efficiently coupled to Bloch modes in two dimensional array of nanopillars, in a two-level high index membrane structure, according to a numerical study. More specifically, when using a slow Bloch mode above the light line, a wavelength selective, directional extraction can occur from the waveguide to the free space. The main conditions to be achieved, such as phase matching, strength of the coupling, photon lifetime in the photonic crystal, influence of embedding... will be discussed.

∂n/∂T measurements performed with guided waves and their application to the temperature sensitivity of wavelength-division multiplexing filters

The Ion Implanted Integrated Optics (I3O) technology, using titanium ion implantation in bulk silica to fabricate passive compact planar lightwave circuits (PLCs), is presented in this paper. Its advantages are described and compared with other waveguide fabrication technologies. It is demonstrated that the guided electromagnetic field can be tailored by adjusting the titanium ion dose either to fit the guided mode of standard single-mode fibers or to allow a sharp radius of curvature of bent waveguides.

Coupling between refractive waveguides and two dimensional photonic crystal Bloch modes

Enhancement of the free-space diffraction efficiency of gratings made by titanium-ion implantation is demonstrated both theoretically and experimentally. Indeed, by insertion of a grating into a multilayer dielectric Fabry-Perot cavity, the diffraction efficiency can be increased to as much as 24 times that of a single grating. The sensitivity of the diffraction efficiency to the optogeometrical parameters of the grating or of the Fabry-Perot cavity is discussed. Moreover, a process for performance of a phase grating inside a Fabry-Perot cavity is described, and experimental results concerning efficiency measurements are compared with computed values for various grating periods.

Ion implanted integrated optics (I3O) technology for planar lightwave circuits fabrication

We present a compact passive optical add-drop filter which incorporates two microring resonators and a waveguide intersection in silicon-on-insulator (SOI) technology. Such a filter is a key element for designing simple layouts of highly integrated complex optical networks-on-chip. The filter occupies an area smaller than 10μm×10μm and exhibits relatively high quality factors (up to 4000) and efficient signal dropping capabilities. In the present work, the influence of filter parameters such as the microring-resonators radii and the coupling section shape are analyzed theoretically and experimentally

Fabry–Perot multilayers for enhancing the diffraction efficiency of ion-implanted gratings

We present a new, one-dimensional, transfer matrix formalism for describing the spectral properties of a quasi-periodic integrated waveguide filter (reflection R, transmission T, overall losses L = 1 - R - T), where losses (essentially due to the modal mismatch between adjacent sections) are modeled as localized, Dirac-like singularities of the (complex) dielectric permittivity. As far as losses appear periodic, the coupling constant between propagating and contra-propagating waves is complex: such a distribution leads to a specific spectral response for L, different from that provided by homogeneous absorption. Besides, the transfer matrix of a unit cell (made of two quarter-wave sections of high and low indices) can be expressed rigorously in the frame of usual coupled-wave equations, even for arbitrary high index contrast. As a result, any periodic section can be represented by one transfer matrix only, whatever the number of unit cells. This can dramatically reduce the computational time by comparison with more accurate simulation tools such as Film Mode Matching (FMM) method.

Analysis of silicon on insulator (SOI) optical microring add-drop filter based on waveguide intersections

The Ion Implanted Integrated Optics (I3O) technology, using titanium ion implantation in bulk silica to fabricate passive compact planar lightwave circuits (PLCs), is presented in this paper. Its advantages are described and compared with other waveguide fabrication technologies. It is demonstrated that the guided electromagnetic field can be tailored by adjusting the titanium ion dose either to fit the guided mode of standard single-mode fibers or to allow a sharp radius of curvature of bent waveguides.

One-dimensional transfer matrix formalism with localized losses for fast designing of quasiperiodic waveguide filters

Sol-gel ZrO2 thin films deposited by dip-coating on various substrates are characterized. The film thickness, the refractive index and the thermo-optic coefficient (δn/δT) are measured using the prism coupler technique. The thickness of the uniform and good quality sol-gel films ranges between 100nm and 130nm, while the refractive index ranges between 1.9 and 2.1 at 25°C, depending on the substrate material and surface quality, and depending on some process parameters. The δn/δT measurements of the sol-gel ZrO2 thin films deposited on several substrates show that the TM refractive index always exhibits much higher dependence with respect to temperature than the TE refractive index. Such variations had not previously been reported and will require much attention and future study due to the importance of δn/δT for advanced optical telecommunications devices.

Ion implanted integrated optics (I3O) technology for planar lightwave circuits (PLCs) fabrication

We numerically demonstrate that the classical thin film computation method (Abeles Computation Method) may be used to obtain reflectance or transmittance of integrated optics filters with a good approximation. Radiative losses are simulated by absorption losses. Results agree well with Film Mode Matching computed optical properties and the computation time can be divided by a factor of 104. Synthesis of integrated Bragg reflectors, narrow band pass filters, high pass filters is presented. Integrated optics filters with non-periodic structures such as gain flattening filters can be easily designed using the Abeles Computation Method. Thus, classical thin film synthesis softwares are useful to design integrated components with arbitrary guided mode spectral reflectance or transmittance. This leads to prospects of new integrated optics functionalities of a great importance such as broadband dispersion compensation for WDM systems or high - order dispersion compensation with non linearly chirped integrated Bragg reflectors.