Integrated polymer photonics : fabrication, design, characterization and applications

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Fabrication and Characterization of Polymeric Optical Waveguides Using Standard Silicon Processing Technology

We report the fabrication and characterization of a rib polymeric waveguide having a thick layer of oxidized porous silicon as an innovative solution for the lower cladding. The waveguide was fabricated using standard silicon substrates and Si-based technology. The multimodal guiding structure has a polymethylmetacrylate (PMMA) core and the innovative lower cladding was obtained by thermal oxidation of a porous silicon layer. The waveguide does not have the upper cladding. Propagation loss measurements were performed at 1.48 \u3bcm using the cut-back method. We obtained propagation loss of about 1.7 dB/cm, confirming the possibility to use the porous silicon oxide as the lower cladding layer, for low cost waveguide applications

Integrated 3D Hydrogel Waveguide Out-Coupler by Step-and-Repeat Thermal Nanoimprint Lithography: A Promising Sensor Device for Water and pH

Hydrogel materials offer many advantages for chemical and biological sensoring due to their response to a small change in their environment with a related change in volume. Several designs have been outlined in the literature in the specific field of hydrogel-based optical sensors, reporting a large number of steps for their fabrication. In this work we present a three-dimensional, hydrogel-based sensor the structure of which is fabricated in a single step using thermal nanoimprint lithography. The sensor is based on a waveguide with a grating readout section. A specific hydrogel formulation, based on a combination of PEGDMA (Poly(Ethylene Glycol DiMethAcrylate)), NIPAAm (N-IsoPropylAcrylAmide), and AA (Acrylic Acid), was developed. This stimulus-responsive hydrogel is sensitive to pH and to water. Moreover, the hydrogel has been modified to be suitable for fabrication by thermal nanoimprint lithography. Once stimulated, the hydrogel-based sensor changes its topography, which is characterised physically by AFM and SEM, and optically using a specific optical set-up

Polymer Resonant Waveguide Gratings

This chapter deals with the advances in polymeric waveguide gratings for filtering and integrated optics applications. Optical polymer materials are widely used for planar and corrugated micro-optical waveguide grating structures ranging from down a micrometer to several hundred micrometers. Light in a polymeric waveguide is transmitted in discrete modes whose propagation orders depend on incident wavelength, waveguide dimensional parameters, and material properties. Diffracted optical structures are permittivity-modulated microstructures whose micro-relief surface profiles exhibit global/local periodicity. The resonant nature and location of such globally periodic structures (diffraction gratings) excite leaky waveguide modes which couple incident light into reflected/transmitted plane wave diffraction orders. It describes design & analysis, fabrication, and characterization of sub-wavelength polymer grating structures replicated in different polymeric materials (polycarbonate, cyclic olefin copolymer, Ormocomp) by a simple, cost-effective, accurate, and large scale production method. The master stamp (mold) for polymer replication is fabricated with an etchless process with smooth surface profile

Nanofabrication of Optofluidic Photonic Crystal Resonators for Biosensing

Advances in nanofabrication have made possible the development of novel nanophotonics based on Photonic Crystal (PhC) structures. Different types of biosensors have been proposed to take advantage of the unique optical properties of PhCs, which, when combined with microfluidics, provide an enabling approach for biomolecule analysis. In this thesis, nanofabrication of a new biosensor structure integrating a 2D PhC nanocavity resonator with an optofluidic channel is described. The recipes for e-beam lithography of PhC and PhC nanocavity patterns were optimized by carefully tuning the e-beam dose as well as control of the resist baking and development conditions. Two PhC fabrication processes based on pattern transfers by lift-off and etch-back were compared. The plasma etching of Si, GaN, and ITO were optimized to obtain fast etching rates, vertical profiles as well as high etch selectivities over different hard masks including Si3N4, SiO2, and Ni. Si, GaN and ITO PhC structures with airhole diameters in the range of 100-200 nm were fabricated using the developed processes. To facilitate the integration of the PhC structures with microfluidic channels, the PhC airholes were sealed with a SiO2 thin film formed by glancing angle deposition. By gradually reducing the flux angle toward normal during deposition, we successfully deposited uniform SiO2 capping layers with minimal material extended down into the PhC airholes. Finally, suspended Si PhC slabs were fabricated on a Si-on-Oxide substrate using an integrated procedure which consists of e-beam lithography, pattern transfer into Si by CF4 plasma etching, and a selective etch of the underlying SiO2 sacrificial layer in HF. The suspended PhC structure provides an important test bed for measuring resonant fluorescence of biomolecules in PhC nanocavities in the IR range

Electrically-pumped, broad-area, single-mode photonic crystal lasers

Planar broad-area single-mode lasers, with modal widths of the order of tens of microns, are technologically important for high-power applications and improved coupling efficiency into optical fibers. They may also find new areas of applications in on-chip integration with devices that are of similar size scales, such as for spectroscopy in microfluidic chambers or optical signal processing with micro-electromechanical systems. An outstanding challenge is that broad-area lasers often require external means of control, such as injection-locking or a frequency/spatial filter to obtain single-mode operation. In this paper, we propose and demonstrate effective index-guided, large-area, edge-emitting photonic crystal lasers driven by pulsed electrical current injection at the optical telecommunication wavelength of 1550nm. By suitable design of the photonic crystal lattice, our lasers operate in a single mode with a 1/e^2 modal width of 25μm and a length of 600μm