In this paper, we present a hybrid process to make a flexible photonic circuit. The photonic circuit is fabricated on a Silicon substrate with PECVD Silicon Nitride (SiN) as a waveguide layer on an oxide layer. The SiN waveguide circuit is fabricated using conventional lithography and dry etching followed by Si substrate thinned down to 10micrometer. The thin-film photonic circuit integrity after wafer-thinning and layer transfer is characterized by the waveguide performance, grating coupler efficiency and ring resonator performance. We observe no degradation in device and circuit performance. We present detailed process flow, SiN-to-PDMS embedding process and detailed device characterization.
In this paper, we demonstrate a compact Silicon photonics-based on-chip integrated interference vibrometer. Unlike conventional readout methods, the demonstrated system is alignment-free and offers multiplex sensing. The intensity that is modulated by the cantilever motion by a photodetector. We present the static and dynamic response of the cantilever by electrostatic excitation validated using ac commercial Laser-Doppler-Vibrometer. We also present a detailed simulation, optimisation and sensitivity analysis of the proposed on-chip vibrometer. Furthermore, the tunability of the sensor to achieve maximum sensitivity is demonstrated.
We demonstrate a compact efficient waveguide taper in Silicon Nitride platform. The proposed taper provides a coupling-efficiency of 95% at a length of 19.5 μm in comparison to the standard linear taper of length 50 μm that connects a 10 μm wide waveguide to a 1 μm wide photonic wire. The taper has a spectral response > 75% spanning over 800 nm (spanning O, C & L band) and robustness to fabrication variations; ±200 nm change in taper and end waveguide width varies transmission by <5%. We experimentally report a taper insertion loss of <0.1 dB/transition and reduction in the footprint of the photonic device by 50.8% for the proposed compact taper in comparison to the traditional adiabatic taper. To the best of our knowledge, the proposed taper is the shortest waveguide taper ever reported in Silicon Nitride.
Optical-Printed Circuit Board (PCB) is an emerging optical interconnect technology to bridge the gap between the board edge and the processing module. The technology so far has been used as a broadband transmitter using polymer waveguides in the PCB. In this paper, we report a Silicon Nitride based photonic IC embedded in the PCB along with the polymers as waveguides in the PCB. The motivation for such integration is to bring routing capability and to reduce the power loss due to broadcasting mode.
In this paper, we demonstrate a compact silicon photonics based vibrometer using an on-chip photonic grating (OPG) based sensor. OPG works on the principle of interference where the motion of the cantilever is captured at the output as an intensity variation. The advantage of OPG based sensor over conventional Laser Doppler vibrometer is increased tolerance to alignment errors as both the grating and the cantilever can be integrated on a single chip. The grating parameters were optimized using 2D-FDTD to achieved maximum sensitivity to the displacement of a cantilever. OPG with on-chip germanium photodetector is studied, which indicates a sensitivity of 54 μW/nm. We experimentally demonstrate the feasibility of the proposed sensor that can achieve a displacement sensitivity of 5.3 μW/nm.