Comparing the fundamental limit of detection for interferometric and resonant biosensors with coherent phase read-out

We compare the limit of detection of coherently interrograted photonic biosensors, using both interferometric and resonant architectures.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Estudio comparativo de biosensors coherentes basados en estructuras interferométricas y resonantes

La gran mayoría de los biosensores fotónicos de campo evanescente se basan en arquitecturas interferométricas o resonantes. La determinación analítica del límite de detección (LOD) alcanzable con estas arquitecturas es muy importante. Sin embargo, hasta donde los autores conocen, no existe un marco común que permita establecer una comparación justa entre ambas alternativas en términos de su LOD intrínseca. En este artículo desarrollaremos un modelo sistémico para biosensores fotónicos, que incluye las posibles pérdidas ópticas y el ruido térmico, a partir de las cuales se puede comparar el LOD intrínseco de ambas arquitecturas. Los resultados obtenidos muestran que la arquitectura interferométrica debe ser la opción preferente para todos aquellos casos en los que la cantidad disponible de analito no es un recurso limitadoUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Este trabajo ha sido parcialmente financiado por el proyecto TEC2016-80718-R del Ministerio de Economía y Competitividad (cofinanciado FEDER) y por la acción Marie Skłodowska-Curie 713721

Systemic comparison of dielectric and plasmonic biosensors on a silicon photonics platform

Plasmonic and dielectric based waveguides are widely used for biosensing applications. However, the use of different sensing architectures and platforms hinders the fair comparison of their respective figures of merit. In this paper, plasmonic and dielectric-based photonic waveguide biosensors are compared in terms of attainable limit of detection, using in both cases a coherent-readout interferometric architectureUniversidad de Málaga; Ministerio de Educación, Cultura y Deporte (MECD) (FPU16/06762); Ministerio de Ciencia e Innovación (MICINN) (PRE2020-096438, PID2019-106747RB-I00); Consejería de Economía, Conocimiento, Empresas y Universidad (CECEU) (UMA18-FEDERJA-219, PY18-793); Consejería de Salud y Familia (CSF) (PIN-0113-2020), Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Diffractive sidewall grating coupler: towards 2D free-space optics on chip.

Silicon photonics has been the subject of intense research efforts. In order to implement complex integrated silicon photonic devices and systems, a wide range of robust building blocks is needed. Waveguide couplers are fundamental devices in integrated optics, enabling different functionalities such as power dividers, spot-size converters, coherent hybrids and fiber-chip coupling interfaces, to name a few. In this work we propose a new type of nanophotonic coupler based on sidewall grating (SIGRA) concept. SIGRAs have been used in the Bragg regime, for filtering applications, as well as in the sub-wavelength regime in multimode interference (MMI) couplers. However, the use of SIGRAs in the radiation regime has been very limited. Specifically, a coarse wavelength division multiplexer was proposed and experimentally validated. In this work we study the use of SIGRAs in the diffractive regime as a mean to couple the light between a silicon wire waveguide mode and a continuum of slab waveguide modes. We also propose an original technique for designing SIGRA based couplers, enabling the synthesis of arbitrary radiation field profile by Floquet- Bloch analysis of individual diffracting elements while substantially alleviating computational load. Results are further validated by 3D FDTD simulations which confirm that the radiated field profile closely matches the target design field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Mitigating reflections in integrated gas sensors

Optical gas sensing for environmental monitoring has become an active research topic in the last decade. Among the different optical sensing configurations, silicon photonic integrated sensors stand as a compact, CMOS-compatible alternative. However, even small on-chip reflections can create significant fringes when the optical path length is varied, e.g., when the wavelength is swept for TDLAS-like measurements. These fringes can be critical for NIR sensors, as absorption signals are much weaker in this region than in the MIR. Here, we propose a signal-processing method based on minimum phase techniques: by increasing the measurement bandwidth to around 2 nm we can completely remove the reflection artifacts through processing.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Designing anisotropy with waveguide subwavelength structures

Silicon sub-wavelength structures have become a versatile design tool for practical, high-performance integrated optical devices, ranging from highly efficient grating couplers to ultra-broadband beam-splitters. Recently, some of the basic anisotropic properties of these structures have been proposed for advance device design. Here we explore these properties in detail, from the underlying physics to emerging applications in on-chip polarization management.Ministerio de Economía y Competitividad, Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad (cofinanciado FEDER), Proyectos TEC2016-80718-R, TEC2015-71127-C2-1-R (FPI scholarship BES-2016-077798), and IJCI-2016-30484, the Community of Madrid (S2013/MIT-2790), the Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech, the EMPIR program (JRP-i22 14IND13 Photind), co-financed by the participating countries and the European Union’s 2020 research and innovation program, and the Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant No. 734331

Colorless devices and reception techniques for polarization multiplexed communications

Future optical networks call for flexible, high performance and low cost coherent optical receivers. We present here several advances towards such receivers, including integrated optical couplers with ultra-broad bandwidth, as well as novel reception techniques and architectures that will enable high performance coherent reception without filtering and polarization splitting elements.Universidad de Málaga - Campus de Excelencia Internacional Andalucía Tech. Spanish Ministry of Science under project TEC2013-46917-C2-1-

Automatic design of high-performance fiber-chip surface grating couplers based on Floquet-Bloch mode analysis

We propose a new strategy to automatically design highly efficient fiber-chip surface grating couplers. High performance designs are achieved with a substantially reduced computational cost by combining Floquet-Bloch mode analysis with a multi-objective optimization technique (genetic algorithms)

Curved waveguide grating demultiplexer (CWG) with a flattened response via bimodal output waveguides

We demonstrate a compact wavelength demultiplexer for the silicon-on-insulator platform based on the curved waveguide grating (CWG) architecture. The proposed device uses bi- modal output waveguides to achieve a low-loss flattened spectral response. The device shows insertion loss as low as 1.2 dB and crosstalk below -20 dB.Universidad de Málaga; Ministerio de Educación, Cultura y Deporte (MECD) (FPU16/03401), Ministerio de Ciencia, Innovación y Universidades (MCIU) (PID2019-106747RBI00), Consejería de Economía, Conocimiento, Empresas y Universidad (CECEU) (UMA18-FEDERJA-219, P18-RT1453, P18-RT-793). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Design of arbitrary optical filters in silicon-on-insulator using evanescently-coupled Bragg gratings

Spectral filters are experiencing an increasing demand in several applications of the silicon- on-insulator (SOI) platform. Many works have demonstrated that arbitrary frequency responses can be synthesized by apodizing the coupling coefficient profile of an integrated Bragg grating. However, the high index contrast of the SOI platform hinders their practical implementation, due to the difficulty of achieving the precise control required in the Bragg strength. In this paper, we propose the implementation of spectral filters using an architecture based on placing loading segments within the evanescent field region of a photonic wire waveguide. The Bragg coupling coefficient can be accurately controlled by simply moving the segments away from, or closer to, the waveguide core. The layerpeeling algorithm, in conjunction with a Floquet-Bloch modal analysis, allows to determine the spatial distribution of the segments that synthesizes the desired spectrum. The proposed topology is verified by designing a filter with five arbitrary passbands.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech