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Showing papers by "Giuseppe Coppola published in 2016"


Journal ArticleDOI
TL;DR: In this article, a review of the state-of-the-art is presented devices based on defect-mediated absorption, two-photon absorption and the internal photoemission effect.
Abstract: Silicon-based technologies provide an ideal platform for the monolithic integration of photonics and microelectronics In this context, a variety of passive and active silicon photonic devices have been developed to operate at telecom and datacom wavelengths, at which silicon has minimal optical absorption - due to its bandgap of 112 eV Although in principle this transparency window limits the use of silicon for optical detection at wavelengths above 11 μm, in recent years tremendous advances have been made in the field of all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths By taking advantage of emerging materials and novel structures, these devices are becoming competitive with the more well-established technologies, and are opening new and intriguing perspectives In this paper, a review of the state-of-the-art is presented Devices based on defect-mediated absorption, two-photon absorption and the internal photoemission effect are reported, their working principles are elucidated and their performance discussed and compared

81 citations


Journal ArticleDOI
19 Aug 2016-Sensors
TL;DR: This work has started from the consideration that if a cell rotates, it is possible to overcome this problem and has designed, realized, and tested two different devices that induce cell rotation in a plane that is parallel to the observation plane.
Abstract: Microfluidic technology allows to realize devices in which cells can be imaged in their three-dimensional shape. However, there are still some limitations in the method, due to the fact that cells follow a straight path while they are flowing in a channel. This can result in a loss in information, since only one side of the cell will be visible. Our work has started from the consideration that if a cell rotates, it is possible to overcome this problem. Several approaches have been proposed for cell manipulation in microfluidics. In our approach, cells are controlled by only taking advantages of hydrodynamic forces. Two different devices have been designed, realized, and tested. The first device induces cell rotation in a plane that is parallel (in-plane) to the observation plane, while the second one induce rotation in a plane perpendicular (out-of-plane) to the observation plane.

21 citations


Journal ArticleDOI
TL;DR: In this article, a combination of holographic and high-specific Raman spectroscopy was used to simultaneously study biochemical and morphological characteristics of human sperm cells irradiated with green laser radiation.
Abstract: Coupling digital holography with high-specific Raman spectroscopy is an attractive means of identifying biochemical changes in cells by both physical topography and spectroscopy. We have used this approach to simultaneously study biochemical and morphological characteristics of human sperm cells irradiated with green laser radiation. Severe spermatozoa variations associated with a topological redistribution of the sample and a gradual decrease in the Raman signal intensity were detected in a label-free configuration. Importantly, at laser fluences where no morphological alterations were detected (30 MJ/cm2), high specific spectral variations were monitored to evaluate the cell photodegradation.

21 citations


Journal ArticleDOI
TL;DR: A new method is presented that generates images of microscopic diatoms with high definition, by merging scanning electron microscopy and digital holography microscopy or atomic force microscopy data, using an original mathematical algorithm implemented on a commercially available software.
Abstract: The frustule of diatoms, unicellular microalgae, shows very interesting photonic features, generally related to its complicated and quasi-periodic micro- and nano-structure. In order to simulate light propagation inside and through this natural structure, it is important to develop three-dimensional (3D) models for synthetic replica with high spatial resolution. In this paper, we present a new method that generates images of microscopic diatoms with high definition, by merging scanning electron microscopy and digital holography microscopy or atomic force microscopy data. Starting from two digital images, both acquired separately with standard characterization procedures, a high spatial resolution (Δz = λ/20, Δx = Δy ≅ 100 nm, at least) 3D model of the object has been generated. Then, the two sets of data have been processed by matrix formalism, using an original mathematical algorithm implemented on a commercially available software. The developed methodology could be also of broad interest in the design and fabrication of micro-opto-electro-mechanical systems.

7 citations


Proceedings ArticleDOI
09 Dec 2016
TL;DR: In this article, the design of an amorphous silicon-based Mach-Zehnder electro-optic modulator including two guiding p-i-n structures integrated inside a two-dimensional (2-D) photonic crystal (PhC) working at 1.55 μm is reported.
Abstract: The design of an amorphous silicon-based Mach-Zehnder electro-optic modulator including two guiding p-i-n structures integrated inside a two-dimensional (2-D) photonic crystal (PhC) working at 1.55 μm, is reported. Electrically induced free carrier dispersion effect in this photonic material with a very cost-effective technology, is investigated for modulation. Our numerical analysis, performed by a time-domain (FDTD)-based software, proves that the voltage-length product can be remarkably reduced by taking advantage of both the strong PhC confinement and the wide refractive index tunability of amorphous silicon.

Proceedings ArticleDOI
01 Oct 2016
TL;DR: In this paper, a Fan shape microheater fabricated on the +Z surface of a LiNbO 3 crystal was used to investigate the pyroelectric effect under humidity conditions.
Abstract: Pyroelectric effect (PE) under humidity conditions from the −Z surface of Lithium Niobate (LiNbO 3 ) crystal was investigated using a Fan shape microheater fabricated on the +Z surface of the crystal. Thermal analyses of the microheater were performed using COMSOL multiphysics and thermal sensor respectively. A resistive Aluminum (Al) sensor was integrated along the microheater in order to control the temperature variation effect from the microheater.

Proceedings ArticleDOI
01 Dec 2016
TL;DR: In this article, the performance of Schottky photodetectors based on materials non-conventionally used to detect near-infrared wavelengths was investigated and shown to have the potential to play a key role in the telecommunications opening new frontiers in the field of low-cost silicon photonics.
Abstract: In this work we have investigated the performance of Schottky photodetectors based on materials non-conventionally used to detect near-infrared wavelengths. In the proposed devices the absorption mechanism is based on the internal photoemission effect. Both three-dimensional (sputtered erbium and evaporated germanium) and two-dimensional materials (graphene) have been considered and their performance compared. Our insights show that silicon Schottky photodetectors have the potentialities to play a key role in the telecommunications opening new frontiers in the field of low-cost silicon photonics.