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Silicon photonic waveguides patterned at the subwavelength level behave as metamaterials whose optical properties, including refractive index, dispersion and anisotropy can be tuned by judiciously designing the subwavelength geometry. Over the past years, the added design freedom afforded by these structures has enabled a wide variety of novel high performance devices, ranging from high efficiency fibre-to-chip couplers, to on-chip polarization and mode management, and ultra-broadband waveguide couplers covering several optical communication bands. In this invited keynote talk we will revisit the physical foundations of these structures, explore some of the latest advances in the field with applications in both telecommunications and sensing, and discuss some of the outstanding challenges to move these structures from research labs to large-scale commercialisation.

Integrated photonic biosensors have demonstrated low bulk detection limits down to 1e−7 refractive index units. Nevertheless, most rely on expensive optical sources, such as DFB lasers. Here, we experimentally demonstrate that with adequate sensor design comparable detection limits are achievable with a low-cost Fabry-Perot laser. European Union’s Horizon 2020, Marie Skłodowska-Curie grant agreement No 713721; Ministerio de Econom ́ıa y Competitividad (FEDER), Proyecto TEC2016-80718-R; Programa Operativo FEDER Andalucía 2014-2020 (UMA18-FEDERJA-219); Severo Ochoa program from Spanish MINECO, Grant No. SEV-2017-0706, Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Silicon photonics enables sensitive and label-free optical biosensors for the detection of chemical and biological substances. Different sensing architectures have been used to improve the limit of detection and increase the dynamic range response. Here, we show experimental limit of detection at state-of-the-art level using silicon nitride integrated Mach-Zehnder interferometers with coherent read-out. These preliminary results are concordant with theoretical results, showing that the proposed approach enables the use of simple read-out equipment using low-cost laser sources.

OSA Advanced Photonics Congress ¿ Integrated Photonics Research, Silicon and Nanophotonics, Washington, DC United States, 13–16 July 2020, In this invited talk we review the latest advances in the surging field of photonic subwavelength metamaterials. These structures can provide enhanced, device-specific material properties and find widespread application in silicon photonics, We acknowledge funding through Universidad de Málaga, Ministerio de Economía y Competitividad (TEC2016- 80718-R, CDTI SNEO-20181232, RTI2018-097957-B-C33), Ministerio de Educación, Cultura y Deporte (FPU16/06762, FPU16/03401, FPU17/00638), Proyecto I+D+i en el marco del Programa Operativo FEDER Andalucía 2014-2020 (UMA18-FEDERJA-219), Czech Science Foundation (Project 190062S), Alcyon Photonics (8.06/5.59.5045), the Community of Madrid – FEDER funds (S2018/NMT-4326), the Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant No. 734331

2020 Photonics North (PN), Niagara Falls, ON, Canada, 26-28 May 2020, Subwavelength structures are enabling a host of high-performances devices in the silicon photonic platform. Here we review our progress in the field, with an emphasis on the auspicious anisotropic properties of these structures for applications ranging from broadband on-chip GRIN-lenses, to zero-birefringence waveguides and polarization splitters.

Integrated photonics devices, based in subwavelength grating (SWG) metamaterials, have shown unprecedented performance in a wide variety of situations. Since their proposal and first experimental demonstration in 2010 designers have made use of the new degrees of freedom provided by these structures to design advanced devices with improved capabilities. The extended design space provided by SWG structures has been successfully used to engineer the refractive index, the dispersion and, more recently, the waveguide birefringence, thus allowing novel advanced device design. In this invited talk we will review some of the advances made by our group in the field., Smart Photonic and Optoelectronic Integrated Circuits XXII, February 1-6, 2020, San Francisco, United States, Series: Proceedings of SPIE

Over the past two decades, integrated photonic sensors have been of major interest to the optical biosensor community due to their capability to detect low concentrations of molecules with label-free operation. Among these, interferometric sensors can be read-out with simple, fixed-wavelength laser sources and offer excellent detection limits but can suffer from sensitivity fading when not tuned to their quadrature point. Recently, coherently detected sensors were demonstrated as an attractive alternative to overcome this limitation. Here we show, for the first time, to the best of our knowledge, that this coherent scheme provides sub-nanogram per milliliter limits of detection in C-reactive protein immunoassays and that quasi-balanced optical arm lengths enable operation with inexpensive Fabry–Perot-type lasers sources at telecom wavelengths., Horizon 2020 Framework Programme (EuroNanoMed 3-H2020 DrNanoDAII); Ministerio de Economía y Competitividad (2019/PCI 2019-2, CTQ2017-86994-R, SEV-2017-0706); Junta de Andalucía, Proyectos Excelencia-Retos (P18-RT-1453, P18-RT-793); Fondos Europeos de Desarrollo Regional (CTQ2016-75870-P, PID2019-104293GB-I00, RD16/0006/0012, TEC2016-80718-R, UMA18-FEDERJA-007, UMA18-FEDERJA-219); H2020 Marie Skłodowska-Curie Actions (713721).

Silicon photonics is one of the most promising candidates to achieve lab-on-a-chip systems. Making use of the evanescent-field sensing principle, it is possible to determine the presence and concentration of substances by simply measuring the variation produced by the light-matter interaction in the real part of the mode effective index (in the near-infrared band), or in its imaginary part in a specific range of wavelengths (in the mid-infrared band). Regardless of which is the operating wavelength range, it is essential to select the proper sensing waveguide in order to maximize the device sensitivity. In this work we will review the potential of diffractionless subwavelength grating waveguides (SWG) for sensing applications by demonstrating their powerful capability to engineer the spatial distribution of the mode profile, and thereby to maximize the light-matter interaction. Among other things, we will demonstrate that the SWG waveguide dimensions used until now in the near-infrared are not optimal for sensing applications. In the mid-infrared band, due to the unacceptable losses of silicon dioxide for wavelengths longer than 4 μm, an additional effort is required to provide a more convenient platform for the development of future applications. In this regard, we will also show our recent progress in the development of a new platform, the suspended silicon waveguide with subwavelength metamaterial cladding. A complete set of elemental building blocks capable of covering the full transparency window of silicon (λ < ∼8.5 μm) will be discussed.

In this work we will review the enormous potential of subwavelength grating waveguides for sensing applications in the near and mid-infrared bands, demonstrating the capability to engineer the mode profile to maximize the light-matter interaction., Optical Sensors, 2019, San Jose, California, USA

OECC / PSC, Fukuoka, Japan, Japan, 7-11 July 2019, Subwavelength grating metamaterials are enabling a new generation of high-performance silicon photonic devices. Here we discuss the fundamental physics along with some of the latest advances in this rapidly expanding field., Funding: Ministerio de Economía y Competitividad, Programa Estatal de Investigación Orientada a los Retos de la Sociedad (cofinanciado FEDER) – TEC2016-80718-R, TEC2015-71127-C2-1-R (FPI BES-2016-077798) and IJCI-2016-30484; Community of Madrid – S2018/NMT-4326, Marie Sklodowska-Curie –734331, Universidad de Málaga, Czech Science Foundation – 1900062S.

Integrated photonic biosensors are capable of detecting trace amounts of biochemical substances without time-consuming labeling steps [1]. Ring resonators and Mach-Zehnder interferometers (MZI) are among the most widely used sensor architectures. The latter can operate with a simple, fixed-wavelength source and have recently shown state-of-the-art limit of detections (LOD) (10−7–10−8 RIU) [2] by using the coherent phase read-out illustrated in Fig. 1(a), overcoming sensitivity fading and directional ambiguity [3]. Sensors using resonant structures often require a wavelength-swept source or broadband source combined with a spectrum analyzer [4]. However, they can also be interrogated with a coherent detection scheme and a fixed wavelength source, shown in Fig. 1(b), making them especially suited for cost sensitive point-of-care devices.

Silicon photonic biosensors hold the potential for highly accurate, yet low cost point-of-care devices. Maximizing the sensitivity of the sensing chips while reducing the complexity and cost of the read-out system is pivotal to realize this potential. Here we present an extensive analysis, both from a practical and a theoretical perspective, of current biosensors, and analyze how subwavelength structures can be exploited to enhance their sensitivity. This study is not restricted just to the near-infrared band as we also determine the sensing capabilities of the suspended silicon waveguides with subwavelength metamaterial cladding working in the mid-infrared range. These waveguides have been recently proposed to cover the full transparency window of silicon ( λ ∼ 8.5 μm), where the fingerprint spectral region of many molecules takes place and so a plethora of evanescent field absorption-based applications will be developed in the near future.

Photonic Integrated Circuits (PIC) will change the fundamental paradigms for the design of multi-color laser engines for life sciences. Exemplified with flow cytometry (FCM), integrated optical technology for visible wavelengths will be shown to open a new spectrum of possibilities to control flow cell illumination patterns, such as the number of output spots, the spot size, and even complex patterns generated by interferometry. Integration of additional optical functions such as variable optical attenuation, wavelength division multiplexing or fast shutters adds value to the PIC. TOPTICA is demonstrating integration of PICs in present Multi-color Laser Engine (MLE) architectures. Multiple wavelengths (405nm, 488nm, 561nm, 640nm) are coupled free space into the chip, leveraging its beam steering COOLAC (Constant Optical Output Level Auto Calibration) technology for automatic realignment, thus overcoming the need of fiber input delivery. Once in the waveguide, the light can be redirected and shaped to a desired output pattern and pitch, reducing the need of discrete optical components. In this work, we will discuss the implementation of various building blocks in PIC technology for MLEs and analyze the advantages over current macroscopic counterparts.

Photonic biosensors offer label-free detection of biomolecules for applications ranging from clinical diagnosis to food quality monitoring. Both sensors based on Mach-Zehnder interferometers and ring resonators are widely used, but are usually read-out using different schemes, making a direct comparison of their fundamental limit of detection challenging. A coherent detection scheme, adapted from optical communication systems, has been recently shown to achieve excellent detection limits, using a simple fixed-wavelength source. Here we present, for the first time, a theoretical model to determine the fundamental limit of detection of such a coherent read-out system, for both interferometric and resonant sensors. Based on this analysis, we provide guidelines for sensor optimization in the presence of optical losses and show that interferometric sensors are preferable over resonant structures when the sensor size is not limited by the available sample volume. Yes