A novel spot-size converter (SSC) incorporating phase matched polycrystalline-silicon (Poly-Si) multi-layer is proposed and optimised for efficient nanophotonic coupling, which can be fabricated by using the CMOS compatible process and can be directly integrated. An efficient algorithm, combining the rigorous H-field based full-vectorial finite element method and the least squares boundary residual method, is developed for the design optimization of the SSC. Use of simple single layer and multi-layer Poly-Si based SSCs are investigated, in which the coupling process, phase matching for isolated and composite waveguides are also carried out. The coupling loss can be reduced to 2.72 dB by using an eleven Poly-Si layers based SSC. The on-chip integrated SSC opens up the feasibility of a low cost passive aligned fiber-pigtailed electronic-photonics integrated circuits platform.

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While 3-D microelectromechanical systems (MEMS) allow switching between a large number of ports in optical telecommunication networks, the development of such systems often suffers from design, fabrication and packaging constraints due to the complex structures, the wafer bonding processes involved, and the tight alignment tolerances between different components. In this work, we present a 2-D translational MEMS platform capable of highly efficient planar optical switching through integration with silicon nitride (SiN) based optical waveguides. The discrete lateral displacement provided by simple parallel plate actuators on opposite sides of the central platform enables switching between different input and output waveguides. The proposed structure can displace the central platform by 3.37 µm in two directions at an actuation voltage of 65 V. Additionally, the parallel plate actuator designed for closing completely the 4.26 µm air gap between the fixed and moving waveguides operates at just 50 V. Eigenmode expansion analysis shows over 99% butt-coupling efficiency the between the SiN waveguides when the gap is closed. Also, 2.5 finite-difference time-domain analysis demonstrates zero cross talk between two parallel SiN waveguides across the length of the platform for a 3.5 µm separation between adjacent waveguides enabling multiple waveguide configuration onto the platform. Different MEMS designs were simulated using static structural analysis in ANSYS. These designs were fabricated with a custom process by AEPONYX Inc. (Montreal, QC, Canada) and through the PiezoMUMPs process of MEMSCAP (Durham, NC, USA).

We present a 1 × 3 optical switch based on a translational microelectromechanical system (MEMS) platform with integrated silicon nitride (SiN) photonic waveguides. The fabricated devices demonstrate efficient optical signal transmission between fixed and suspended movable waveguides. We report a minimum average insertion loss of 4.64 dB and a maximum average insertion loss of 5.83 dB in different switching positions over a wavelength range of 1530 nm to 1580 nm. The unique gap closing mechanism reduces the average insertion loss across two air gaps by a maximum of 7.89 dB. The optical switch was fabricated using a custom microfabrication process developed by AEPONYX Inc. This microfabrication process integrates SiN waveguides with silicon-on-insulator based MEMS devices with minimal stress related deformation of the MEMS platform.

We present the analytical modelling and experimental characterization of a new design of silicon nitride tunable bandpass filter based on serially coupled ring resonators assisted Mach-Zehnder interferometer (SR-MZI). SR-MZI filters provide an additional degree of freedom to independently control the bandwidth and shape of the passband as compared to previous ring-assisted MZI filters. It is possible to tune the bandwidth, shape and side-band rejection of the response by adjusting the coupling in the filters, providing a scope for fully reconfigurable performance. The fabrication of the filters is CMOS compatible and supports mass production. Preliminary results for thermal controllability are presented.