Renan Moreira

Design of integrated hybrid silicon waveguide optical gyroscope

We propose and analyze a novel highly integrated optical gyroscope using low loss silicon nitride waveguides. By integrating the active optical components on chip, we show the possibility of reaching a detection limit on the order of 19°/hr/√Hz in an area smaller than 10 cm(2). This study examines a number of parameters, including the dependence of sensitivity on sensor area.

Multilayer Platform for Ultra-Low-Loss Waveguide Applications

We investigate a multilayer vertical stacking scheme for use in the Silicon Nitride-based low-loss waveguide platform. In this letter, we use common fabrication techniques to produce test structures for probing the interactions between vertically separated parallel waveguide planes and the characteristics of vertical directional couplers. Single-mode and multimode waveguide geometries are investigated, with designs similar to our previously demonstrated ultra-low-loss technologies. Group index measurements via narrowband OFDR reveal an index mismatch between the vertically separated waveguides of 8.6e-3, generated by the stress of the deposited upper cladding. Vertical directional couplers with a 3-μm vertical coupling gap and a 50 nm × 4 μm geometry exhibited an excess coupling loss of 0.19±0.20 dB and cross-coupled power of 54%, limited by the aforementioned velocity mismatch. The 1.23-m spiral structures with perpendicular crossings on adjacent layers show a transmission loss of the crossings below 0.25 dB for a multimode geometry, while the single-mode design showed a minimum crossing loss of 1.0 dB.

Sidewall gratings in ultra-low-loss Si 3 N 4 planar waveguides

We demonstrate sidewall gratings in an ultra-low-loss Si3N4 planar waveguide platform. Through proper geometrical design we can achieve coupling constant values between 13 and 310 cm(-1). The TE waveguide propagation loss over the range of 1540 to 1570 nm is below 5.5 dB/m.

Integrated ultra-low-loss silicon nitride waveguide coil for optical gyroscopes

We demonstrate, for the first time, a Sagnac sensor using an on-chip 3m ultra-low-loss silicon nitride waveguide coil.

Optical Interconnect for 3D Integration of Ultra-Low Loss Planar Lightwave Circuits

We demonstrate the fabrication of a low loss broadband vertical coupler for use in the 3D integration of Si3N4 based planar waveguides. Coupling loss of 0.2 dB was achieved and interaction between layers investigated.

Fabrication and demonstration of a pure silica-core waveguide utilizing a density-based index contrast

We report a novel approach for creating a dopant-free pure silica-core waveguide (PSCW) for chip-scale waveguides with the goal of reaching fiber-like losses on-chip. Stoichiometric silica films were used as both the cladding and core material for buried channel waveguides, with the required index contrast generated by a difference in physical density. The bulk densities of the thin-films were measured with X-Ray Reflectometry, and these density values were compared with the expected change in refractive index using the Lorentz-Lorenz (Clausius-Mosotti) relation. We found the difference in density of 5.29% to correspond with the difference in refractive index of 1.17%, and measured propagation losses of 2.119 to 2.660 dB/cm.

Programmable eye-opener lattice filter for multi-channel dispersion compensation using an integrated compact low-loss silicon nitride platform

A tunable eye-opening lattice filter for dispersion compensation is demonstrated on an ultra low-loss waveguide platform based on a compact high-aspect ratio Si3N4 core. A programmable 10th order lattice filter is demonstrated by cascading a total of 21 Mach-Zehnder interferometers with programmable delay lines of lengths designed at the baseband data rate. The filter has a footprint of 2.23 cm2 with continuously tunable dispersion from -500 ps/nm to 500 ps/nm. The filter shows a periodic transfer function with a measured FSR of 100 GHz capable of compensating multiple WDM channels with a single device.

Microtune - a simple monolithic widely tunable laser: Design, Fabrication, and Characterization

The design and simulation of a novel compact tunable laser is presented. Preliminary results match theoretical predictions. A tuning range greater than 30 nm with >30dB SMSR has been demonstrated.