Breakthroughs in Photonics 2013: Toward Feedback-Controlled Integrated Photonics

We present an overview of the main achievements obtained in 2013 on the monitoring, stabilization, and feedback loop control of passive and active photonic integrated circuits. Key advances contributed to the evolution of photonic technologies from the current device level toward complex, adaptive, and reconfigurable integrated circuits

A variable delay integrated receiver for differential phase-shift keying optical transmission systems

An integrated variable delay receiver for DPSK optical transmission systems is presented. The device is realized in silicon-on-insulator technology and can be used to detect DPSK signals at any bit-rates between 10 and 15 Gbit/s

Multipurpose silicon photonics signal processor core

[EN] Integrated photonics changes the scaling laws of information and communication systems offering architectural choices that combine photonics with electronics to optimize performance, power, footprint, and cost. Application-specific photonic integrated circuits, where particular circuits/chips are designed to optimally perform particular functionalities, require a considerable number of design and fabrication iterations leading to long development times. A different approach inspired by electronic Field Programmable Gate Arrays is the programmable photonic processor, where a common hardware implemented by a two-dimensional photonic waveguide mesh realizes different functionalities through programming. Here, we report the demonstration of such reconfigurable waveguide mesh in silicon. We demonstrate over 20 different functionalities with a simple seven hexagonal cell structure, which can be applied to different fields including communications, chemical and biomedical sensing, signal processing, multiprocessor networks, and quantum information systems. Our work is an important step toward this paradigm.J.C. acknowledges funding from the ERC Advanced Grant ERC-ADG-2016-741415 UMWP-Chip, I.G. acknowledges the funding through the Spanish MINECO Ramon y Cajal program. D.P. acknowledges financial support from the UPV through the FPI predoctoral funding scheme. D.J.T. acknowledges funding from the Royal Society for his University Research Fellowship.Pérez-López, D.; Gasulla Mestre, I.; Crudgington, L.; Thomson, DJ.; Khokhar, AZ.; Li, K.; Cao, W.... (2017). Multipurpose silicon photonics signal processor core. Nature Communications. 8(1925):1-9. https://doi.org/10.1038/s41467-017-00714-1S1981925Doerr, C. R. & Okamoto, K. Advances in silica planar lightwave circuits. J. Lightw. Technol. 24, 4763–4789 (2006).Coldren, L. A. et al. High performance InP-based photonic ICs—A tutorial. J. Lightw. Technol 29, 554–570 (2011).Soref, R. The past, present, and future of silicon photonics. IEEE J. Sel. Top. Quantum Electron. 12, 1678–1687 (2006).Bogaerts, W. Design challenges in silicon photonics. IEEE J. Sel. Top. Quantum Electron. 20, 8202008 (2014).Bogaerts, W. et al. Nanophotonic waveguides in silicon-on-insulator fabricated with CMOS technology. J. Lightw. Technol. 23, 401–412 (2005).Smit, M. K. et al. An introduction to InP-based generic integration technology. Semicond. Sci. Technol. 29, 083001 (2014).Leinse, A. et al. TriPleX waveguide platform: low-loss technology over a wide wavelength range. Proc. SPIE 8767, 87670E (2013).Kish, F. et al. From visible light-emitting diodes to large-scale III–V photonic integrated circuits. Proc. IEEE 101, 2255–2270 (2013).Heck, M. J. R. et al. Hybrid silicon photonic integrated circuit technology. IEEE J. Sel. Top. Quantum Electron. 19, 6100117 (2013).Sacher, W. et al. Multilayer silicon nitride-on-silicon integrated photonic platforms and devices. J. Lightw. Technol. 33, 901–910 (2015).Asghari, M. Silicon photonics: A low cost integration platform for datacom and telecom applications. In OFC/NFOEC 2008 – 2008 Conference on Optical Fiber Communication/National Fiber Optic Engineers Conference 1–10 (San Diego, USA, 2008).Melati, D. et al. Integrated all-optical MIMO demultiplexer for mode- and wavelength-division-multiplexed transmission. Opt. Lett. 42, 342–345 (2017).Waterhouse, R. & Novak, D. Realizing 5G: microwave photonics for 5G mobile wireless systems. IEEE Microw. Mag. 16, 84–92 (2015).Marpaung, D. et al. Integrated microwave photonics. Laser Photon. Rev. 7, 506–538 (2013).Iezekiel, S., Burla, M., Klamkin, J., Marpaung, D. & Capmany, J. RF engineering meets optoelectronics: Progress in integrated microwave photonics. IEEE Microw. Mag. 16, 28–45 (2015).Technology focus on microwave photonics. Nat. Photon. 5, 723 (2011).Ghelfi, P. et al. A fully photonics-based coherent radar system. Nature 507, 341–345 (2014).Heideman, R. G. TriPleX™-based integrated optical ring resonators for lab-ona-chip-and environmental detection. IEEE J. Sel. Top. Quantum Electron. 18, 1583–1596 (2012).Estevez, M. C., Alvarez, M. & Lechuga, L. Integrated optical devices for lab-on-a-chip biosensing applications. Laser Photon. Rev. 6, 463–487 (2012).Almeida, V. R., Barrios, C. A., Panepucci, R. & Lipson, M. All-optical control of light on a silicon chip. Nature 431, 1081–1084 (2004).Norberg, E. J., Guzzon, R. S., Parker, J. S., Johansson, L. A. & Coldren, L. A. Programmable photonic microwave filters monolithically integrated in InP/InGaAsP. J. Lightw. Technol. 29, 1611–1619 (2011).Wang, J. et al. Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip. Nat. Commun. 6, 5957 (2015).Hill, M. T. et al. A fast low power optical memory based on coupled micro-ring lasers. Nature 432, 206–209 (2004).Slavík, R. et al. Photonic temporal integrator for all-optical computing. Opt. Express 16, 18202–18214 (2008).Sun, C. et al. A monolithically-integrated chip-to-chip optical link in bulk CMOS. IEEE J. Solid-State Circ. 50, 828–844 (2015).Sun, C. et al. Single-chip microprocessor that communicates directly using light. Nature 528, 534–538 (2015).Assefa, S. et al. in Optical Fibre Communication Conference OMM6, https://www.osapublishing.org/abstract.cfm?uri=OFC-2011-OMM6 (Optical Society of America, 2011).Peruzzo, A. et al. Multimode quantum interference of photons in multiport integrated devices. Nat. Commun. 2, 224 (2011).Bonneau, D. et al. Quantum interference and manipulation of entanglement in silicon wire waveguide quantum circuits. N. J. Phys. 14, 045003 (2012).Metcalf, B. J. et al. Multiphoton quantum interference in a multiport integrated photonic device. Nat. Commun. 4, 1356 (2013).Muñoz, P. et al. in 16th International Conference on Transparent Optical Networks (ICTON), 1–4 (Graz, 2014).Ribeiro, A. et al. Demonstration of a 4×4-port universal linear circuit. Optica 3, 1348–1357 (2016).Liu, W. et al. A fully reconfigurable photonic integrated signal processor. Nat. Photon 10, 190–195 (2016).Graydon, O. Birth of the programmable optical chip. Nat. Photon 10, 1 (2016).Pérez, D., Gasulla, I. & Capmany, J. Software-defined reconfigurable microwave photonics processor. Opt. Express 23, 14640–14654 (2015).Miller, D. A. B. Self-configuring universal linear optical component. Photon. Res. 1, 1–15 (2013).Miller, D. A. B. Self-aligning universal beam coupler. Opt. Express 21, 6360–6370 (2013).Clements, W. R. et al. Optimal design for universal multiport interferometers. Optica 3, 1460–1465 (2016).Zhuang, L., Roeloffzen, C. G. H., Hoekman, M., Boller, K.-J. & Lowery, A. J. Programmable photonic signal processor chip for radiofrequency applications. Optica 2, 854–859 (2015).Capmany, J., Gasulla, I. & Pérez, D. Microwave photonics: The programmable processor. Nat. Photon. 10, 6–8 (2016).Pérez, D., Gasulla., Capmany, J. & Soref, R. A. Reconfigurable lattice mesh designs for programmable photonic processors. Opt. Express 24, 12093–12106 (2016).Madsen, C. K. & Zhao, J. H. Optical Filter Design and Analysis: A Signal Processing Approach. 1st edn. (Wiley, 1999).Jinguji, K. Synthesis of coherent two-port lattice-form optical delay-line circuit. J. Lightw. Technol. 13, 73–82 (1995).Jinguji, K. Synthesis of coherent two-port Optical delay-line circuit with ring waveguides. J. Lightw. Technol. 14, 1882–1898 (1996).Madsen, C. K. General IIR optical filter design for WDM applications using all-pass filters. J. Lightw. Technol. 18, 860–868 (2000).Burla, M. et al. On-chip CMOS compatible reconfigurable optical delay line with separate carrier tuning for microwave photonic signal processing. Opt. Express 19, 21475–21484 (2011).Yariv, A. et al. Coupled resonator optical waveguides: a proposal and analysis. Opt. Lett. 24, 711–713 (1999).Hebner, J. E. et al. Distributed and localized feedback in microresonator sequences for linear and nonlinear optics. J. Opt. Soc. Am. B. 21, 1665–1673 (2004).Fandiño, J. S. et al. A monolithic integrated photonic microwave filter. Nat. Photon. 11, 124–129 (2017).Miller, D. A. B. All linear optical devices are mode converters. Opt. Express 20, 23985–23993 (2012).Reck, M. et al. Experimental realization of any discrete unitary operator. Phys. Rev. Lett. 73, 58–61 (1994).Carolan, J. et al. Universal linear optics. Science 349, 711 (2015).Nielsen, M. A. & Chuang, I. L. Quantum Computation and Quantum Information. 1st edn. (Cambridge University Press, 2001).Miller, D. A. B. Perfect optics with imperfect components. Optica 2, 747–750 (2015).Grillanda, S. et al. Non-invasive monitoring and control in silicon photonics using CMOS integrated electronics. Optica 1, 129–136 (2014)

Settlement analysis of the masonry umbrella vault of the Masegra Castle

In this work, the first results on the settlement analysis of the masonry umbrella vault located in the Masegra Castle (Sondrio, Italy) are presented. An umbrella vault is a particular type of cross vault in which the high number of sails is disposed according to an umbrella-shaped configuration. For geometry reasons, these vaults presents typically a good load-bearing capacity when subjected to vertical and horizontal loads. Therefore, the most critical issue is given by settlements of the supporting walls. A geometrical model based on NURBS surfaces has been derived starting from a detailed point cloud. A recently published method based on an adaptive kinematic limit analysis is adopted to find the cracks configuration deriving from a given base settlement

A novel genetic algorithm homogeneous approach for the in-plane analysis of masonry walls subjected to settlements

This work presents an investigation on the in-plane behavior of a masonry wall that is subjected to a ground settlement in its bottom-right corner. Three distinct modeling strategies are here employed: the first two are the traditional heterogeneous and homogeneous approaches, the third a novel Genetic Algorithm adaptive homogeneous approaches. The traditional heterogeneous approach adopts a discretization of the masonry wall in which each brick is modeled as a single element. The traditional homogenous approach instead adopts a mesh consisting of triangular elements, which are considered as rigid blocks. For this latter case, the failure surfaces of the interfaces are obtained through a homogenization procedure. Eventually, the GA-adaptive homogeneous approach adopts a mesh consisting of a limited number of rectangular elements; subsequently, the initial mesh is iteratively modified to identify automatically the actual position of the cracks originated from the application of the settlement. It is also shown that the GA-adaptive homogeneous approach requires a reduced computational effort with respect to the traditional techniques

Heuristic molecular modelling of quasi-isotropic auxetic metamaterials under large deformations

A two-dimensional molecular model is presented for the elastic non-linear modelling and design of meta-materials. The fundamental unit-cell, based on a heuristic molecule (HM) approach, is composed of atoms that interact through centred and non-centred spring-based bonds. The kinematics formulation allows to consider large displacements and finite strains while the specific topology of the HM can be parametrized to modify the shape of the rigid atoms and the size of the bonds. The HM is frame indifferent and provides a remarkable quasi-isotropic elastic response for both deviatoric and volumetric large deformation modes. At a macro-scale, the relationship with different continuum materials is given through a standard isotropic Cauchy up to an isotropic Cosserat solid. Evidence on the interest of the model as a calculation tool is provided by studying the elastic response of standard and auxetic materials subjected to a non-homogeneous deformation field, as well as the response of auxetic foams under large deformations. Aside the numerical agreement, it is highlighted how the tailoring of the HM topology can be effective to approximate the non-linear geometric effects that occur at finer scales of auxetic foams. In perspective, we address how the exotic mechanical properties provided by the HM, together with the assumed physical-driven framework, can foster the engineering application and the design of new meta-materials

A Genetic Algorithm adaptive homogeneous approach for evaluating settlement-induced cracks in masonry walls

This paper presents a Genetic Algorithm adaptive homogeneous approach aiming at representing the crack patterns induced by ground settlements on masonry walls. This type of damage is a critical issue since it affects all masonry buildings, including those that are not located in seismic-prone areas. The GA-adaptive homogeneous approach here proposed is meant as a tool that overcomes the usual high computational costs requested by the traditional heterogeneous and homogeneous approaches. Here, the considered masonry wall is discretized into a low number of 2D polygonal elements; its displacement field is then determined through a linear programming problem. The actual position of cracks induced by the applied settlement is identified by modifying the initial mesh through an iterative mesh adaptation procedure performed with a Genetic Algorithm (GA); the iterations are carried on until the absolute minimum of the work performed by the reaction forces is attained. In this way, the computational effort needed for identifying the actual crack patterns is dramatically decreased due to the very few unknowns of the problem. The reliability of the GA-adaptive homogeneous approach here proposed is validated against selected benchmarks that come from experimental and numerical results, and is also compared with the traditional heterogeneous and homogeneous approaches. In all the three benchmarks, the GA-adaptive approach offers a satisfying computational efficiency and identifies the actual crack patterns with good accuracy, despite the low number of elements employed in the discretization of the masonry wall. This may pave the way for a broader use of this approach in the analysis of complex masonry structures affected by settlement-induced damages

Roughness Induced Backscattering and Polarization Rotation in Optical Waveguides

In this contribution we experimentally investigate backscattering and polarization rotation induced by sidewall roughness in silicon-on-insulator (SOI) optical waveguides. Waveguides with different widths, different upper cladding and longitudinally tapered have been measured and compared. All the measurements have been performed by means of an advanced frequency domain interferometric technique, which allows the evaluation of both amplitude and phase of backscatter as well as its polarization

Adaptative Limit Analysis of in-Plane Loaded Partially Grouted Reinforced Masonry Shear Walls

An adaptative limit analysis is employed to simulate the lateral in-plane lateral response of partially-grouted reinforced concrete shear walls made of hollow concrete blocks. The wall is modeled through rigid plane elements. Internal plastic dissipation is evaluated at the edges only according to experimentally measured ultimate resistance values. A mesh adaptation scheme is applied to find the correct position of fracture lines during the failure. The results were validated by comparing with the experimental results of full-scale tests of only-vertically reinforced and bed-joint reinforced walls. A good match was found in the prediction of the lateral bearing capacity as well as the failure mode

SHM of a severely cracked masonry arch bridge in India: Experimental campaign and adaptive NURBS limit analysis numerical investigation

The paper presents some SHM results belonging to a wide experimental campaign conducted on a multi-arch masonry bridge located near Mumbai (India), exhibiting a large longitudinal crack on one of the arches and the corresponding advanced numerical evaluations carried out with a NURBS kinematic limit analysis approach, used to assess the stability of the arch subjected to the passage of heavy traffic loads. The masonry bridge is a three-arch structure built during the mid-19th century by British engineers to connect Bombay with the inland of the Indian subcontinent. At present, it is characterized by a heavy state of degradation especially in one of the arches that requires an immediate evaluation of the safety under the passage of traffic loads and possible ideas of interventions to strengthen the structure, in order to avoid the propagation of deep cracks along the longitudinal direction. The adopted SHM includes the crack growth monitoring and tilting of the spandrels under the application of two different heavy loads (a water tank truck and a hydra crane) located in different positions of the arch. Numerical modelling is carried out with a full 3D approach with NURBS finite elements in limit analysis that takes into account the pre-existing crack opening and predicts with great accuracy the ultimate loads in different scenarios and the corresponding active failure mechanisms. From experimental monitoring and numerical simulations results, it is concluded that the bridge is still safe under the passage of traffic loads, but approaches the ultimate limit state for some specific configurations of the loads applied. A refurbishment is therefore needed to avoid any further propagation of the cracks up to collapse