Nonlinear applications in the mid-infrared regime based on germanium on silicon platform

This abstract reviews our progress in characterizing nonlinear properties of low loss germanium-on-silicon waveguides in the mid-infrared wavelength. All-optical modulation is demonstrated in these waveguides and indicates the suitability of this platform for nonlinear applications in this long wavelength regime

Suspended silicon integrated platform for the long-wavelength mid-infrared band

The atmospheric-transmission window and the fingerprint region of many substances overlaps with the long-wave infrared band. This has enabled the emergence of a new path for photonic integrated circuits, which could exploit the potential applications of this wavelength range, including chemical and bio sensing. In this work we review our latest advances in the suspended silicon platform with subwavelength grating lateral cladding at 7.7-µm wavelength. Suspended waveguides only require one lithographic etch step and can be specifically designed to maximize sensitivity when used as sensors. Waveguides with propagation loss of 3.1±0.3 dB/cm are demonstrated, as well as bends with less than 0.1 dB/bend. Suspended waveguides based on shifted Bragg grating lateral cladding are also reported, with propagation loss of 5.1±0.6 dB/cm. These results prepare the ground for the development of a platform capable of covering the entire mid-infrared band. Keywords: suspended silicon, mid-infrared, long-wave infrared, subwavelength grating, Bragg.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Broadband 2 × 2 multimode interference coupler for mid-infrared wavelengths

Versión aceptada del artículo publicado en Optics Letters (https://doi.org/10.1364/OL.439985).Beam splitters are core components of photonic integrated circuits and are often implemented with multimode interference couplers. While these devices offer high performance, their operational bandwidth is still restrictive for sensing applications in the mid-infrared wavelength range. Here we experimentally demonstrate a subwavelength-structured 2×2 multimode interference coupler with high performance in the 3.1−3.7µm range, doubling the bandwidth of a conventional device

High performance silicon photonic devices based on practical metamaterials

Robert Halir, et al., "High performance silicon photonic devices based on practical metamaterials," OECC/PSC, 7-12 July 2019, Fukuoka (Japan)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.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. 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, Czech Science Foundation – 1900062

Suspended silicon waveguides for long-wave infrared wavelengths

In this Letter, we report suspended silicon waveguides operating at a wavelength of 7.67 μm with a propagation loss of 3.1±0.3 dB/cm. To our knowledge, this is the first demonstration of low-loss silicon waveguides at such a long wavelength, with loss comparable to other platforms that use more exotic materials. The suspended Si waveguide core is supported by a sub-wavelength grating that provides lateral optical confinement while also allowing access to the buried oxide layer so that it can be wet etched using hydrofluoric acid. We also demonstrate low-loss waveguide bends and s-bends

Silicon high performance devices using subwavelength structures

Ministerio de Economía y Competitividad, Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad (cofinanciado FEDER), Proyecto TEC2016-80718-R Universidad de MälagaSilicon photonics is poised to solve challenges in areas such as datacom, environmental monitoring and diagnostics, by leveraging the economies of scale afforded by CMOS manufacturing. This requires a wide variety of integrated silicon devices, including fiber-to-chip couplers, polarization splitters and waveguide couplers, operating both in the near-infrared and the mid-infrared wavelength range. However, the reduced set of materials available in this platform can often limit the performance of these devices. Subwavelength structures enable the synthesis of optical metamaterials, with properties than can be tuned to enhance device performance, by using fully etched silicon structures with a periodicity smaller than the wavelength of light. Here we review the basic operating principles of these structures, discuss how to efficiently model them, and report on the latest advances in this rapidly growing field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Subwavelength-grating metamaterial integrated devices for the near- and mid-infrared wavelengths

The subwavelength patterning of planar structures is now widely used in silicon photonics, enabling the synthesis of metamaterials with engineered optical properties, including refractive index, dispersion, and anisotropy. A wide range of integrated devices based on subwavelength grating (SWG) metamaterials have been demonstrated at telecom wavelengths, some with unprecedented performance. The benefits of SWG metamaterials can be leveraged not only in the typical telecom near-infrared bands, but also at the longer mid-infrared wavelengths. In this invited presentation, we will review our latest developments in SWG-based silicon and germanium photonic devices for the near- and the mid-infrared.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Subwavelength-engineered metamaterial devices for integrated photonics

The engineering of subwavelength grating metamaterials has become an essential design strategy in silicon photonics. The lithographic segmentation of integrated waveguides at the subwavelength scale enables the synthesis of on-chip metamaterials and provides control over optical properties such as mode delocalization, wavelength dispersion, and anisotropy. At the near-infrared wavelengths of the 1.55-μm telecom band, a range of subwavelength-based devices with unprecedented performance has been demonstrated, including couplers, filters, and polarization-handling structures. In this invited paper, we review the foundations of anisotropic subwavelength grating metamaterials and discuss our latest advances in five new subwavelength-enhanced devices: a millimeter-long optical antenna that is evanescently coupled to diffractive lateral segments, thereby achieving a record far-field beam width of 0.1º in silicon; a multi-line integrated Bragg filter also using lateral loading segments, which produces 20 non-uniformly spaced spectral notches with a 3-dB linewidth as low as 210 pm; a low-loss curved wavelength demultiplexer; a segmented multi-mode interference coupler based on novel bricked subwavelength gratings, yielding a 1-dB bandwidth exceeding 140 nm; and a suspended waveguide platform with low propagation loss at mid-infrared wavelengths.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Building high-performance integrated optical devices using subwavelength grating metamaterials

Ministerio de Ciencia, Innovación y Universidades (MCIU) (PID2019-106747RB-I00), Consejería de Economía, Conocimiento, Empresas y Universidad (CECEU) (UMA18-FEDERJA-219, P18-RT-1453, P18-RT-793) and National Research Council of Canada (NRC) Collaborative Science, Technology and Innovation Program (CSTIP) (HTSN 209).The use of subwavelength grating structures in silicon waveguides have fuelled the development of integrated optical components with superior performance. By a judicious lithographic pattern of the grating, the optical properties of the synthesized metamaterial can be accurately tailored. In this work, we review our latest advances in subwavelength-grating-engineered silicon and germanium planar devices.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Mid-infrared suspended waveguide platform and building blocks

In this work, the authors present their recent progress in the development of a platform for the mid-infrared wavelength range, based on suspended silicon waveguides with subwavelength metamaterial cladding. The platform has some intrinsic advantages, which make it a very promising candidate for sensing applications in the molecular fingerprint region. Specifically, it can cover the full transparency window of silicon (up to a wavelength of 8 μm), only requires one lithographic etch-step and can be designed for strong light–matter interaction. Design rules, practical aspects of the fabrication process and experimental results of a complete set of elemental building blocks operating at two very different wavelengths, 3.8 and 7.7 μm, are discussed. Propagation losses as low as 0.82 dB/cm at λ0 = 3.8 μm and 3.1 dB/cm at λ0 = 7.7 μm are attained for the interconnecting waveguides