Special Issue "Advanced Optical Materials and Devices"

A special issue of Photonics (ISSN 2304-6732).

Deadline for manuscript submissions: 30 November 2019.

Special Issue Editors

Guest Editor
Prof. Dr. Orlando Frazão Website E-Mail
INESC-TEC and Department of Physics and Astronomy, University of Porto, Porto, Portugal
Interests: optical fiber sensors; optical communications
Guest Editor
Dr. Susana Silva Website E-Mail
INESC-TEC, Porto, Portugal
Interests: Optical fiber sensors for monitoring of physical parameters, interrogation systems based on optical fiber rings, microstructured fibers for Raman spectroscopy
Guest Editor
Dr. Paulo A. Ribeiro Website E-Mail
Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
Interests: featured materials and devices; thin film processing; polymeric thin films; electrical and optical characterization of materials; sensor device assembly and interfacing; development of scientific instrumentation
Guest Editor
Dr. Maria Raposo Website E-Mail
Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
Interests: physico-chemical interfacial phenomena at the solid-liquid interface; physics and chemistry of macromolecules surfaces and interfaces; featured of surfaces and interfaces; dedicated assemblies for in-situ monitoring, dynamics at surfaces and interfaces, adsorption and desorption processes; artificial membrane development and characterization; thin film sensor devices; characterization of molecular sensors and devices; molecularly imprinted films

Special Issue Information

Dear Colleagues,

This Special Issue presents many important contributions to this emergent field of research in Advanced Optical Materials and Devices.

The main topics will include new inorganic and organic optical materials, semiconductors, smart materials, nano structures, metamaterials, plasmonics, nanocarbon, nanotubes, graphene, and bio-inspired materials. The objective of this Special Issue is also to present photonics devices based on these main material topics and their applications in engineering, medicine, the environment, and others.

The Guest Editors encourage the submission of new contributions with new results and research solutions in the field of "Materials and Advanced Optical Devices".

Prof. Orlando Frazão
Dr. Susana Silva
Dr. Paulo A. Ribeiro
Dr. Maria Raposo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (8 papers)

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Research

Open AccessArticle
Ultrafast Hyperspectral Transient Absorption Spectroscopy: Application to Single Layer Graphene
Photonics 2019, 6(3), 95; https://doi.org/10.3390/photonics6030095 - 29 Aug 2019
Abstract
We describe the basic principles and the experimental implementation of the hyperspectral transient absorption technique, based on femtosecond laser sources. In this technique the samples were optically “pumped” using the femtosecond tunable pulse delivered by an Optical Parametric Amplifier, and “probed” for changes [...] Read more.
We describe the basic principles and the experimental implementation of the hyperspectral transient absorption technique, based on femtosecond laser sources. In this technique the samples were optically “pumped” using the femtosecond tunable pulse delivered by an Optical Parametric Amplifier, and “probed” for changes in transmission in a broad spectral range with a “white light” laser-generated supercontinuum. The spectra were collected by a pair of multichannel detectors which allowed retrieval of the absorbance change in a wide spectral range in one time. The use of the supercontinuum probe introduced artifacts in the measured 2D data set which could be corrected with a proper calibration of the chirp. The configuration with crossed polarization for pump and probe pulse extended the spectral measured range above and below the pump energy within the same experiment. We showed the versatility of the technique by applying it to the investigation of the charge carrier dynamics in two-dimensional single layer graphene. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
Generation of Coherent and Spatially Squeezed States of an Electromagnetic Beam in a Planar Inhomogeneous Dielectric Waveguide
Photonics 2019, 6(3), 84; https://doi.org/10.3390/photonics6030084 - 30 Jul 2019
Abstract
We use slow-varying amplitude approximation (SVA) for the wave equation to study both analytically and numerically propagation of an electromagnetic beam in the waveguide structure with parabolic susceptibility spatial dependence. Such a structure is similar to the harmonic oscillator in quantum mechanics. We [...] Read more.
We use slow-varying amplitude approximation (SVA) for the wave equation to study both analytically and numerically propagation of an electromagnetic beam in the waveguide structure with parabolic susceptibility spatial dependence. Such a structure is similar to the harmonic oscillator in quantum mechanics. We analyze this structure as a single mode guide and introduce the notion of number of “photons” in the mode. In particular, we pay special attention to the possibility of effective build-up of the coherent and spatially squeezed vacuum states of the mode that can be of interest for a number of practical applications. The way to provide these types of mode excitation is suggested. Several applications for controlling the mode composition of an electromagnetic wave in the parabolic index-gradient waveguide for various frequency ranges are considered. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
The Theoretical Concept of Polarization Reflectometric Interference Spectroscopy (PRIFS): An Optical Method to Monitor Molecule Adsorption and Nanoparticle Adhesion on the Surface of Thin Films
Photonics 2019, 6(3), 76; https://doi.org/10.3390/photonics6030076 - 30 Jun 2019
Abstract
In this paper, we present an improved reflectometric interference spectroscopy (RIfS) sensor principle which is suitable for thin films. The conventional RIfS technique is an appropriate method to detect interfacial interactions at the solid–gas or solid–liquid interface in the case of thin films [...] Read more.
In this paper, we present an improved reflectometric interference spectroscopy (RIfS) sensor principle which is suitable for thin films. The conventional RIfS technique is an appropriate method to detect interfacial interactions at the solid–gas or solid–liquid interface in the case of thin films with a thickness of a few hundred nanometers, but when a significantly lower layer thickness (~100 nm) is required, the method is barely usable. By applying polarized reflected light and monitoring the ratio of the p- and s-polarized components, a characteristic curve can be obtained with one or a few local extreme value(s) with significantly favorable intensity ratios compared to the conventional method. In this work we studied the effect of film thickness, incident angle and the refractive indices of the thin film, the medium and the substrate. As a main result, it was demonstrated that the sensitivity of the PRIfS method is 4–7 times higher than that of the conventional technique near a critical angle. In simulated adsorption experiments, it was determined that the sensitivity of RIfS is around 550 nm/RIU (refractive index unit), while it is 1825 and 3966 nm/RIU for PRIfS in gas and aqueous phase, respectively. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
Third-Order Nonlinear Spectrum of GaN under Femtosecond-Pulse Excitation from the Visible to the Near Infrared
Photonics 2019, 6(2), 69; https://doi.org/10.3390/photonics6020069 - 18 Jun 2019
Abstract
Gallium nitride (GaN) has been established as a promising candidate for integrated electro-optic and photonic devices, aiming at applications from optical switching to signal processing. Studies of its optical nonlinearities, however, lack spectral coverage, especially in the telecommunications range. In this study, we [...] Read more.
Gallium nitride (GaN) has been established as a promising candidate for integrated electro-optic and photonic devices, aiming at applications from optical switching to signal processing. Studies of its optical nonlinearities, however, lack spectral coverage, especially in the telecommunications range. In this study, we measured the two-photon absorption coefficient (β) and the nonlinear index of refraction (n2) of GaN from the visible to the near-infrared by using femtosecond laser pulses. We observed an increase of β from (1.0 ± 0.2) to (2.9 ± 0.6) ×10−11 m/W as the photon energy approached the band gap from 1.77 up to 2.25 eV (700–550 nm), while n2 varied from (90 ± 30) ×10−20 up to (265 ± 80) ×10−20 m2/W within a broad spectral range, from 0.80 up to 2.25 eV (1550–550 nm). The results were modeled by applying a theory based on the second-order perturbation theory and the Kramers-Kronig relationship for direct-gap semiconductors, which are important for the development of GaN-based nonlinear photonic devices. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
An Optical Power Divider Based on Mode Coupling Using GaN/Al2O3 for Underwater Communication
Photonics 2019, 6(2), 63; https://doi.org/10.3390/photonics6020063 - 03 Jun 2019
Cited by 1
Abstract
This paper details the design of a 1 × 8 optical power divider, using a gallium nitride (GaN) semiconductor on sapphire, which can be applied to underwater optical wireless communication. The design consists of nine parallel rectangular waveguides which are based on mode [...] Read more.
This paper details the design of a 1 × 8 optical power divider, using a gallium nitride (GaN) semiconductor on sapphire, which can be applied to underwater optical wireless communication. The design consists of nine parallel rectangular waveguides which are based on mode coupling phenomena. Analysis of the design was performed using the beam propagation method (BPM). The optimization was conducted using the 3D finite difference (FD)-BPM method with an optical signal input at the wavelength required for maritime application of λ = 0.45 µm. The signal was injected into the central waveguide. The results showed that at a propagation length of 1480 µm the optical power is divided into eight output beams with an excess loss of 0.46 dB and imbalance of 0.51 dB. The proposed design can be further developed and applied in future underwater communication technology. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
Synthesis of Nanostructure InxGa1−xN Bulk Alloys and Thin Films for LED Devices
Photonics 2019, 6(2), 44; https://doi.org/10.3390/photonics6020044 - 24 Apr 2019
Abstract
In this study, we investigated an innovative method for the fabrication of nanostructure bulk alloys and thin films of indium gallium nitride (InxGa1−xN) as active, thin films for light-emitting diode (LED) devices using both crystal growth and thermal vacuum [...] Read more.
In this study, we investigated an innovative method for the fabrication of nanostructure bulk alloys and thin films of indium gallium nitride (InxGa1−xN) as active, thin films for light-emitting diode (LED) devices using both crystal growth and thermal vacuum evaporation techniques, respectively. These methods resulted in some tangible improvements upon the usual techniques of InxGa1−xN systems. A cheap glass substrate was used for the fabrication of the LED devices instead of sapphire. Indium (In) and Gallium (Ga) metals, and ammonia (NH3) were the precursors for the alloy formation. The alloys were prepared at different growth temperatures with compositions ranging from 0.1 ≤ x ≤ 0.9. InxGa1−xN alloys at 0.1 ≤ x ≤ 0.9 had different crystallinities with respect to X-Ray diffraction (XRD) patterns where the energy bandgap that was measured by photoluminescence (PL) fell in the range between 1.3 and 2.5 eV. The bulk alloys were utilized to deposit the thin films onto the glass substrate using thermal vacuum evaporation (TVE). The XRD thin films that were prepared by TVE showed high crystallinity of cubic and hexagonal structures with high homogeneity. Using TVE, the InxGa1−xN phase separation of 0.1 ≤ x ≤ 0.9 was eliminated and highly detected by XRD and FESEM. Also, the Raman spectroscopy confirmed the structure that was detected by XRD. The FESEM showed a variance in the grain size of both alloys and thin films. The InxGa1−xN LED device with the structure of glass/GaN/n-In0.1Ga0.9N:n/In0.1Ga0.9N/p-In0.1Ga0.9N:Mg was checked by the light emitted by electroluminescence (EL). White light generation is a promising new direction for the fabrication of such devices based on InxGa1−xN LED devices with simple and low-cost techniques. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
Epsilon-Near-Zero Absorber by Tamm Plasmon Polariton
Photonics 2019, 6(1), 28; https://doi.org/10.3390/photonics6010028 - 09 Mar 2019
Cited by 3
Abstract
Two schemes of excitation of a Tamm plasmon polariton localized at the interface between a photonic crystal and a nanocomposite with near-zero effective permittivity have been investigated in the framework of the temporal coupled-mode theory. The parameters of the structure have been determined, [...] Read more.
Two schemes of excitation of a Tamm plasmon polariton localized at the interface between a photonic crystal and a nanocomposite with near-zero effective permittivity have been investigated in the framework of the temporal coupled-mode theory. The parameters of the structure have been determined, which correspond to the critical coupling of the incident field with a Tamm plasmon polariton and, consequently, ensure the total absorption of the incident radiation by the structure. It has been established that the spectral width of the absorption line depends on the scheme of Tamm plasmon polariton excitation and the parameters of a nanocomposite film. The features of field localization at the Tamm plasmon polariton frequency for different excitation schemes have been examined. It has been demonstrated that such media can be used as narrowband absorbers based on Tamm plasmon polaritons localized at the interface between a photonic crystal and a nanocomposite with near-zero effective permittivity. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Open AccessArticle
A Bio-Compatible Fiber Optic pH Sensor Based on a Thin Core Interferometric Technique
Photonics 2019, 6(1), 11; https://doi.org/10.3390/photonics6010011 - 30 Jan 2019
Abstract
There is an increasing demand for compact, reliable and versatile sensor concepts for pH-level monitoring within several industrial, chemical as well as bio-medical applications. Many pH sensors concepts have been proposed, however, there is still a need for improved sensor solutions with respect [...] Read more.
There is an increasing demand for compact, reliable and versatile sensor concepts for pH-level monitoring within several industrial, chemical as well as bio-medical applications. Many pH sensors concepts have been proposed, however, there is still a need for improved sensor solutions with respect to reliability, durability and miniaturization but also for multiparameter sensing. Here we present a conceptual verification, which includes theoretical simulations as well as experimental evaluation of a fiber optic pH-sensor based on a bio-compatible pH sensitive material not previously used in this context. The fiber optic sensor is based on a Mach-Zehnder interferometric technique, where the pH sensitive material is coated on a short, typically 20-25 mm thin core fiber spliced between two standard single mode fibers. The working principle of the sensor is simulated by using COMSOL Multiphysics. The simulations are used as a guideline for the construction of the sensors that have been experimentally evaluated in different liquids with pH ranging from 1.95 to 11.89. The results are promising, showing the potential for the development of bio-compatible fiber optic pH sensor with short response time, high sensitivity and broad measurement range. The developed sensor concept can find future use in many medical- or bio-chemical applications as well as in environmental monitoring of large areas. Challenges encountered during the sensor development due to variation in the design parameters are discussed. Full article
(This article belongs to the Special Issue Advanced Optical Materials and Devices)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Femtosecond third-order nonlinear spectrum of GaN from visible to near- infrared
F. B. Almeida1, S. N. C. Santos1, J. P. Siqueira1, J. Dipoldi1, A. Jaros2, I. Manglano-Clavero2, C. Margenfeld2, A. Waag2, T. Voss2 and C. R. Mendonça1
1
Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, SP, Brazil
2 Institute of Semiconductor Technology and Laboratory for Emerging Nanometrology LENA, Technische Universität Braunschweig, Braunschweig, Germany

From Rabi-type oscillations to generation of coherent and spatially squeezed states of electromagnetic beam in waveguide structures
Anna Bogatskaya, Alexander Popov
Physical Institute, RAS,  Department of Physics, Moscow State University, Moscow , Russia

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