Towards Simultaneous Absorption and Refractive Index Sensing using Integrated Photonics.

Photonic integrated sensors traditionally detect changes either in optical amplitude or phase. Here we experimentally demonstrate a sensing architecture which measures both amplitude and phase, enabling simultaneous detection of changes in absorption and refractive index.This work has received funding from the Ministerio de Ciencia, Innovación y Universidades (FPU19/03330, PID2019-106747RB-I00) and the Junta de Andalucía (Agencia Andaluza del Conocimiento PY18-793). We would also like to acknowledge the Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech

Efficient fiber-to-chip grating coupler for micrometric SOI rib waveguides

Grating couplers are an efficient means for fiber to chip coupling, as they require no facet preparation and enable wafer scale testing. While grating couplers are commonly used in silicon wire waveguides, their application to micrometric silicon-on-insulator rib waveguides is complicated due to the presence of high-order Bloch modes. We study the Bloch modes behavior and their excitation determined by access waveguide design. The latter is implemented to enable single Bloch mode excitation. The use of a design process based on modal analysis is proposed. A grating coupler is proposed in silicon-on-insulator with 1.5 microm thick silicon layer that achieves a coupling efficiency of 65.6% at 1.55 microm. The structure, including interconnection waveguides, access waveguide and grating can be fabricated using a single lithography step

Optimizing the limit of detection of waveguide-based interferometric biosensor devices

Waveguide-based photonic sensors provide a unique combination of high sensitivity, compact size and label-free, multiplexed operation. Interferometric configurations furthermore enable a simple, fixed-wavelength read-out making them particularly suitable for low-cost diagnostic and monitoring devices. Their limit of detection, i.e., the lowest analyte concentration that can be reliably observed, mainly depends on the sensors response to small refractive index changes, and the noise in the read-out system. While enhancements in the sensors response have been extensively studied, noise optimization has received much less attention. Here we show that order-of-magnitude enhancements in the limit of detection can be achieved through systematic noise reduction, and demonstrate a limit of detection of ~10 RIU with a silicon nitride sensor operating at telecom wavelengths

High performance TM-pass polarizer via subwavelength grating bandgap engineering

Silicon photonics systems exhibit a strong birefrin- gence which makes polarization management critical. Here we demonstrate, with full 3D-FDTD simulations, a low-loss and high- extinction ratio TM-pass polarizer based on tilted subwavelength gratings that reflects the TE0 mode into the TE1 mode, with a 150 nm bandwidth.Junta de Andalucía (P18-RT-793 and P18-RT-1453); Universidad de Málaga (UMA20-FEDERJA-158); Ministerio de Economía y Competitividad (PID2019-106747RB-I00); Ministerio de Ciencia e Innovación (TED2021- 130400B-I00); Ministerio de Universidades (FPU19/02408); Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Low-loss curved waveguide grating wavelength demultiplexer

We demonstrate a compact wavelength demultiplexer for the silicon on insulator platform based on the curved waveguide grating (CWG) architecture. We mitigate off-chip radiation loss by enforcing the single beam condition by using metamaterial index engineering. The fabricated device exhibits insertion loss as low as 1dB and crosstalk lower than -25 dB

Polarization insensitive metamaterial engineered multimode interference coupler in a 220 nm silicon-on-insulator platform

High-index contrast silicon waveguides exhibit strong birefringence that hinders the development of polarization-insensitive devices, especially for sub-micrometer silicon layer thickness. Here a polarizationindependent 2 × 2 multimode interference coupler in a 220 nm silicon-on-insulator platform is designed and experimentally demonstrated for the first time. Leveraging the advanced control of electromagnetic properties provided by a subwavelength grating metamaterial topology, our multimode interference coupler operates for both TE and TM polarization states with measured polarization dependent loss, insertion loss and imbalance all less than 1 dB, and phase errors below 5◦ in the wavelength range from 1500 nm to 1560 nm. The device has a footprint of only 3.5 μm × 47.25 μm and was fabricated using a single etch-step process with a minimum feature size of 100 nm compatible with immersion deep-UV lithography.We acknowledge funding from Ministerio de Economía y Competitividad (PID2019106747RB-I00), Junta de Andalucía (P18-RT-1453, UMA-FEDERJA-158), Ministerio de Ciencia, Innovaci ́on y Universidades (FPU16/06762, FPU19/02408), and Universidad de Málaga. Funding for open access charge: Universidad de Málaga / CBUA

Metamaterial antenna array fed by distributed Bragg deflector for beam steering on SOI platform

The capability to radiate collimated steerable beams of light is crucial for many applications, such as remote sensing and free-space optical communications. Here we experimentally demonstrate a novel 1D-antenna array architecture that exhibits a far-field Gaussian profile with an angular divergence of 1.8° × 0.2°.We acknowledge funds from National Research Council of Canada (NRC) Collaborative Science, Technology and Innovation Program (CSTIP) (HTSN 209); Ministerio de Ciencia, Innovación y Universidades (MCIU) (PID2019- 106747RB-I00); Ministerio de Universidades (FPU16/03401, FPU20/03487); Junta de Andalucía (P18-RT-1453, P18-RT- 793); FEDER Andalucía (UMA20-FEDERJA-158). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

An Ultracompact GRIN-Lens-Based Spot Size Converter using Subwavelength Grating Metamaterials

AbstractGraded‐index materials offer virtually complete control over light propagation in integrated photonic chips but can be challenging to implement. Here, an anisotropic graded‐index metamaterial, synthesized with fully etched silicon subwavelength structures, is proposed. Based on this material, a spot size converter that expands the transverse electric (TE) mode field profile from a 0.5 µm wide silicon wire waveguide to a 15 µm wide waveguide within a length of only 14 µm is designed. Measured insertion losses are below 1 dB in an unprecedented 130 nm bandwidth, limited by the measurement setup, with full 3D finite‐difference time‐domain (FDTD) simulations predicting a bandwidth in excess of 300 nm. Furthermore, the device is well suited to feed fiber‐to‐chip grating couplers, while requiring a footprint ten times smaller than conventional adiabatic tapers