From several years till now the aerospace industry is developing more and more small satellites f... more From several years till now the aerospace industry is developing more and more small satellites for Low-Earth Orbit (LEO) missions. Such satellites have a low cost of making and launching since they have a size and weight smaller than other types of satellites. However, because of size limitations, small satellites need integrated electronic equipment based on digital logic. Moreover, the LEOs require telecommunication modules with high throughput to transmit to earth a big amount of data in a short time. In order to meet such requirements, in this paper we propose a Telemetry, Tracking & Command module optimized through the use of the Commercial Off-The-Shelf components. The proposed approach exploits the major flexibility offered by these components in reducing costs and optimizing the performance. The method has been applied in detail for the design of the front-end receiver, which has a low noise figure (1.5 dB) and DC power consumption (smaller than 2 W). Such a performance is ...
2021 IEEE 8th International Workshop on Metrology for AeroSpace (MetroAeroSpace), 2021
The future generation of Very High Throughput Satellites (VHTS) for telecommunication purposes wi... more The future generation of Very High Throughput Satellites (VHTS) for telecommunication purposes will bring a huge impact in terms of payload mass, volume and power consumption requirements in order to meet the increased capacity and achievable performance demand. The introduction of the photonic technology, which is already well developed for terrestrial networks, can represent one of the possible approaches to reduce the payload system complexity. This paper provides a brief overview on possible applications of microwave/photonic technologies to implement operations needed in a Satellite Communication (SATCOM) payload, focusing on advantages of Radio Frequency (RF) signal mixing in the photonic domain. A configuration scheme of a photonic RF mixer based on a dual port Mach-Zehnder Modulator (MZM) and two photonic local oscillators, used as RF downconverter, is presented and discussed.
Graphene is a material with exceptional optical, electrical and physicochemical properties that c... more Graphene is a material with exceptional optical, electrical and physicochemical properties that can be combined with dielectric waveguides. To date, several optical devices based on graphene have been modeled and fabricated operating in the near-infrared range and showing excellent performance and broad application prospects. This paper covers the main aspects of the optical behaviour of graphene and its exploitation as electrodes in several device configurations. The work compares the reported optical devices focusing on the wavelength tuning, showing how it can vary from a few hundred up to a few thousand picometers in the wavelength range of interest. This work could help and lead the design of tunable optical devices with integrated graphene layers that operate in the NIR.
This paper reports the experimental results of a test campaign performed on the radio-frequency (... more This paper reports the experimental results of a test campaign performed on the radio-frequency (RF) receiver prototype operating at a 2025–2110 MHz frequency range, designed and fabricated for CubeSat applications. The prototype has been tested through a board-level test approach for the verification of the functional requirements and a component-level one for specific characterization measures. The tests have shown the following results: a −115–−70 dBm sensitivity range, 390 MHz intermediate frequency, a 0 dBm output power level with ±1 dB error, a 2.34 dB noise figure, and a 4.86 W power absorption. Such results have been largely achieved implementing an automatic gain control system by cascading two Commercial Off-The-Shelf (COTS) amplifiers. Moreover, an innovative technique based on RF test points has been successfully experimented and validated to measure the S-parameters of a custom low-pass filter integrated on the receiver, showing the possibility of even characterizing th...
ORIGINAL ARTILLE Michele Bozzctti, Giovanna Calo, Antonella D'Orazio, Marco ... more ORIGINAL ARTILLE Michele Bozzctti, Giovanna Calo, Antonella D'Orazio, Marco De Sario, Vincenzo Petmzzelli, Francesco Prudenzano, Nicola Diaferi a, Cataldo Bonaventura ... different grain sizes, which decrease from sample A to sample D. We can see that the real pan of the ...
Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XIV, 2016
We present a strategy to control Fano resonances in hybrid graphene-silicon-on-insulator gratings... more We present a strategy to control Fano resonances in hybrid graphene-silicon-on-insulator gratings. The presence of a mono- or few-layer graphene film allows to electrically and/or chemically tuning the Fano resonances that result from the interaction of narrow-band, quasi-normal modes and broad-band, Fabry-Perot-like modes. Transmission, reflection and absorption spectra undergo significant modulations under the application of a static voltage to the graphene film. In particular, for low values of the graphene chemical potential, the structure exhibits a symmetric Lorentzian resonance; when the chemical potential increases beyond a specific threshold, the grating resonance becomes Fano-like, hence narrower and asymmetric. This transition occurs when the graphene optical response changes from that of a lossy dielectric medium into that of a low-loss metal. Further increasing the chemical potential allows to blue-shift the Fano resonance, leaving its shape and linewidth virtually unaltered. We provide a thorough description of the underlying physics by resorting to the quasi-normal mode description of the resonant grating and retrieve perturbative expressions for the characteristic wavelength and linewidth of the resonance. The roles of number of graphene layers, waveguide-film thickness and graphene quality on the tuning abilities of the grating will be discussed. Although developed for infrared telecom wavelengths and silicon-on-insulator technology, the proposed structure can be easily designed for other wavelengths, including visible, far-infrared and terahertz, and other photonic platforms.
We report a strategy to modulate the Fano-like signature of a guided-mode resonance supported by ... more We report a strategy to modulate the Fano-like signature of a guided-mode resonance supported by a graphene-based grating. The shape of the resonance is controlled by the amount of damping introduced by graphene. A symmetric-to-asymmetric line shape transition and a significant narrowing of the linewidth occur at relatively moderate levels of chemical potential. Further increases of the chemical potential lead to a blueshift of the Fano resonance due to the modification of the imaginary part of the conductivity of graphene. Our results are supported by a quasi-normal mode analysis of the grating. Using a perturbative approach, we provide analytical expressions for both the resonance wavelength shift and the linewidth modulation induced by changes of the graphene’s chemical potential. Electrostatic or electrochemical gating of graphene in the proposed structure provides dynamic control of the Fano-like resonance of the grating, suggesting new opportunities for the design of tunable photonic and optoelectronic devices at infrared wavelengths.
Bio-inspired Dielectric Resonator Antennas (DRAs) are engaging more and more attention from the s... more Bio-inspired Dielectric Resonator Antennas (DRAs) are engaging more and more attention from the scientific community due to their exceptional wideband characteristic, which is especially desirable for the implementation of 5G communications. Nonetheless, since these antennas exhibit peculiar geometries in their micro-features, high dimensional accuracy must be accomplished via the selection of the most suitable fabrication process. In this study, the challenges to the manufacturing process presented by the wideband Spiral shell Dielectric Resonator Antenna (SsDRA), based on the Gielis superformula, are addressed. Three prototypes, made of three different photopolymer resins, were manufactured by bottom-up micro-Stereolithography (SLA). This process allows to cope with SsDRA’s fabrication criticalities, especially concerning the wavy features characterizing the thin spiral surface and the micro-features located in close proximity to the spiral origin. The assembly of the SsDRAs with ...
Through the years, inspiration from nature has taken the lead for technological development and i... more Through the years, inspiration from nature has taken the lead for technological development and improvement. This concept firmly applies to the design of the antennas, whose performances receive a relevant boost due to the implementation of bio-inspired geometries. In particular, this idea holds in the present scenario, where antennas working in the higher frequency range (5G and mm-wave), require wide bandwidth and high gain; nonetheless, ease of fabrication and rapid production still have their importance. To this aim, polymer-based 3D antennas, such as Dielectric Resonator Antennas (DRAs) have been considered as suitable for fulfilling antenna performance and fabrication requirements. Differently from numerous works related to planar-metal-based antenna development, bio-inspired DRAs for 5G and mm-wave applications are at their beginning. In this scenario, the present paper proposes the analysis and optimization of a bio-inspired Spiral shell DRA (SsDRA) implemented by means of G...
We report on the numerical simulations and experimental validation of a microwave planar sensor b... more We report on the numerical simulations and experimental validation of a microwave planar sensor based on two coupled rings operating in the 4–6 GHz range. The fabricated sensor is used to characterize the dielectric permittivity of vegetable oils. We optimized the geometrical parameters in order to improve the overlap between the oil samples under study and the electric field. The experimental results showed an excellent match with the simulation results. The fabricated sensor allowed to retrieve the oil permittivity with a sensitivity of about 35 MHz per permittivity unit in the frequency range of interest. This paves the way to the realization of compact and sensitive sensors for a wide plethora of fields ranging from industry and food to chemistry and biology.
In this study, we present a two-dimensional dielectric grating which allows achieving high absorp... more In this study, we present a two-dimensional dielectric grating which allows achieving high absorption in a monolayer graphene at visible and near-infrared frequencies. Dielectric gratings create guided-mode resonances that are exploited to effectively couple light with the graphene layer. The proposed structure was numerically analyzed through a rigorous coupled-wave analysis method. Effects of geometrical parameters and response to the oblique incidence of the plane wave were studied. Numerical results reveal that light absorption in the proposed structure is almost insensitive to the angle of the impinging source over a considerable wide angular range of 20°. This may lead to the development of easy to fabricate and experimentally viable graphene-based absorbers in the future.
In this paper, we numerically and experimentally demonstrate how to modulate the amplitude and ph... more In this paper, we numerically and experimentally demonstrate how to modulate the amplitude and phase of a microwave ring resonator by means of few-layers Chemical Vapour Deposition (CVD) graphene. In particular, both numerical and experimental results show a modulation of about 10 dB and a 90 degrees-shift (quadrature phase shift) when the graphene sheet-resistance is varied. These findings prove once again that graphene could be efficiently exploited for the dynamically tuning and modulation of microwave devices fostering the realization of (i) innovative beam-steering and beam-forming systems and (ii) graphene-based sensors.
ABSTRACT In this paper we propose a tunable notch filter based on an index confined photonic band... more ABSTRACT In this paper we propose a tunable notch filter based on an index confined photonic band gap waveguide. Properly designed periodic corrugated overlay allows the dropping of the electromagnetic wave at a given wavelength. The tunability is reached by exploiting the electroclinic effect of the smectic-A* liquid crystals. All numerical results are obtained by a computer code based on bidirectional beam propagation method using the method of lines. INTRODUCTION The growing interest about photonic crystals in the recent years is mainly due to their capability of modifying the flow of light, allowing the electromagnetic wave at some frequencies to pass through the periodic structures or forbidding other frequencies propagation, thus forming a photonic band gap (PBG) in specific frequency range. An optical PBG structure is characterised by a monodimensional, or two-dimensional, or three-dimensional periodic permittivity so that a light beam which passes through it, reflects and transmits itself many times and it can be propagated or stopped [1-4]. For many applications it is advantageous to obtain some degree of tunability of the basic characteristics and this occurrence is usually obtained through the electro-optic effects. A possibility of performing very interesting figures of tuning, recently tested on PBG devices, is offered by the use of self assembling dielectrics infiltrated with liquid crystals (LC) [5]. The aim of this paper is devoted to the construction of infiltrated liquid crystal photonic crystals (ILCPC) and to the demonstration of electric tuning of the photonic band gap. What it makes liquid crystals attractive for optical applications is mainly the large variety of potential interactions [6] which exploit electro-optic, magneto-optic and acousto-optic effects, some of these having very large strength. As an example, the electro-optic coefficient strength of a nematic liquid crystals is orders of magnitude larger than that of the best electro-optic solid material. Moreover, it is well known that the use of LC in conjunction with optical waveguides for switching light allows to obtain compact devices characterised by a very short switching length [7]. In a previous paper [8] we showed how changing the kind of employed LC, the same self-assembled threedimensional (3D) PBG structure, consisting of layers of square rods, joined by vertical posts, can act as a switch or a continuous tunable filter. The choice of the liquid crystal depends on the operation function to be performed: so the fast and bistable molecular switching of the ferroelectric smectic C* 3M2CPOOB was exploited for the first application, whereas for the second application, the electro-clinic effect, peculiar of the chiral orthogonal smectic A* ZLI4237100, was used. In this last case, the tilt angle is allowed to be continuously controlled from zero to some practical value and consequently to obtain a tunable band-structure when the periodic lattice is infiltrated with the liquid crystal. In this paper we propose a tunable notch filter based on a index confined one dimensional photonic band gap (IC-1D-PBG) waveguide. NUMERICAL RESULTS The structure under examination is depicted in Fig.1. The waveguide consists of a Si 3 N 4 layer d g =500 nm thick having refractive index n g =2, deposited onto SiO 2 substrate (n s =1.45), wavelength λ µm; the superstrate is air. A periodic corrugated overlay constituted by a finite number of N alternating layers of air and Si 3 N 4 is introduced, in order to obtain a one-dimensional periodic structure. The tooth height h=120 nm, the width of the air grooves is w 1 =444 nm and the width of the Si 3 N 4 teeth is w 2 =10 nm corresponding to a total spatial period Λ nm.
We investigate nonlinear properties of a one-dimensional photonic crystal with a graphene-based d... more We investigate nonlinear properties of a one-dimensional photonic crystal with a graphene-based defect, and show that the field enhancement provided by the photonic crystal cavity enhances third harmonic generation and lowers the threshold of nonlinear processes.
From several years till now the aerospace industry is developing more and more small satellites f... more From several years till now the aerospace industry is developing more and more small satellites for Low-Earth Orbit (LEO) missions. Such satellites have a low cost of making and launching since they have a size and weight smaller than other types of satellites. However, because of size limitations, small satellites need integrated electronic equipment based on digital logic. Moreover, the LEOs require telecommunication modules with high throughput to transmit to earth a big amount of data in a short time. In order to meet such requirements, in this paper we propose a Telemetry, Tracking & Command module optimized through the use of the Commercial Off-The-Shelf components. The proposed approach exploits the major flexibility offered by these components in reducing costs and optimizing the performance. The method has been applied in detail for the design of the front-end receiver, which has a low noise figure (1.5 dB) and DC power consumption (smaller than 2 W). Such a performance is ...
2021 IEEE 8th International Workshop on Metrology for AeroSpace (MetroAeroSpace), 2021
The future generation of Very High Throughput Satellites (VHTS) for telecommunication purposes wi... more The future generation of Very High Throughput Satellites (VHTS) for telecommunication purposes will bring a huge impact in terms of payload mass, volume and power consumption requirements in order to meet the increased capacity and achievable performance demand. The introduction of the photonic technology, which is already well developed for terrestrial networks, can represent one of the possible approaches to reduce the payload system complexity. This paper provides a brief overview on possible applications of microwave/photonic technologies to implement operations needed in a Satellite Communication (SATCOM) payload, focusing on advantages of Radio Frequency (RF) signal mixing in the photonic domain. A configuration scheme of a photonic RF mixer based on a dual port Mach-Zehnder Modulator (MZM) and two photonic local oscillators, used as RF downconverter, is presented and discussed.
Graphene is a material with exceptional optical, electrical and physicochemical properties that c... more Graphene is a material with exceptional optical, electrical and physicochemical properties that can be combined with dielectric waveguides. To date, several optical devices based on graphene have been modeled and fabricated operating in the near-infrared range and showing excellent performance and broad application prospects. This paper covers the main aspects of the optical behaviour of graphene and its exploitation as electrodes in several device configurations. The work compares the reported optical devices focusing on the wavelength tuning, showing how it can vary from a few hundred up to a few thousand picometers in the wavelength range of interest. This work could help and lead the design of tunable optical devices with integrated graphene layers that operate in the NIR.
This paper reports the experimental results of a test campaign performed on the radio-frequency (... more This paper reports the experimental results of a test campaign performed on the radio-frequency (RF) receiver prototype operating at a 2025–2110 MHz frequency range, designed and fabricated for CubeSat applications. The prototype has been tested through a board-level test approach for the verification of the functional requirements and a component-level one for specific characterization measures. The tests have shown the following results: a −115–−70 dBm sensitivity range, 390 MHz intermediate frequency, a 0 dBm output power level with ±1 dB error, a 2.34 dB noise figure, and a 4.86 W power absorption. Such results have been largely achieved implementing an automatic gain control system by cascading two Commercial Off-The-Shelf (COTS) amplifiers. Moreover, an innovative technique based on RF test points has been successfully experimented and validated to measure the S-parameters of a custom low-pass filter integrated on the receiver, showing the possibility of even characterizing th...
ORIGINAL ARTILLE Michele Bozzctti, Giovanna Calo, Antonella D'Orazio, Marco ... more ORIGINAL ARTILLE Michele Bozzctti, Giovanna Calo, Antonella D'Orazio, Marco De Sario, Vincenzo Petmzzelli, Francesco Prudenzano, Nicola Diaferi a, Cataldo Bonaventura ... different grain sizes, which decrease from sample A to sample D. We can see that the real pan of the ...
Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XIV, 2016
We present a strategy to control Fano resonances in hybrid graphene-silicon-on-insulator gratings... more We present a strategy to control Fano resonances in hybrid graphene-silicon-on-insulator gratings. The presence of a mono- or few-layer graphene film allows to electrically and/or chemically tuning the Fano resonances that result from the interaction of narrow-band, quasi-normal modes and broad-band, Fabry-Perot-like modes. Transmission, reflection and absorption spectra undergo significant modulations under the application of a static voltage to the graphene film. In particular, for low values of the graphene chemical potential, the structure exhibits a symmetric Lorentzian resonance; when the chemical potential increases beyond a specific threshold, the grating resonance becomes Fano-like, hence narrower and asymmetric. This transition occurs when the graphene optical response changes from that of a lossy dielectric medium into that of a low-loss metal. Further increasing the chemical potential allows to blue-shift the Fano resonance, leaving its shape and linewidth virtually unaltered. We provide a thorough description of the underlying physics by resorting to the quasi-normal mode description of the resonant grating and retrieve perturbative expressions for the characteristic wavelength and linewidth of the resonance. The roles of number of graphene layers, waveguide-film thickness and graphene quality on the tuning abilities of the grating will be discussed. Although developed for infrared telecom wavelengths and silicon-on-insulator technology, the proposed structure can be easily designed for other wavelengths, including visible, far-infrared and terahertz, and other photonic platforms.
We report a strategy to modulate the Fano-like signature of a guided-mode resonance supported by ... more We report a strategy to modulate the Fano-like signature of a guided-mode resonance supported by a graphene-based grating. The shape of the resonance is controlled by the amount of damping introduced by graphene. A symmetric-to-asymmetric line shape transition and a significant narrowing of the linewidth occur at relatively moderate levels of chemical potential. Further increases of the chemical potential lead to a blueshift of the Fano resonance due to the modification of the imaginary part of the conductivity of graphene. Our results are supported by a quasi-normal mode analysis of the grating. Using a perturbative approach, we provide analytical expressions for both the resonance wavelength shift and the linewidth modulation induced by changes of the graphene’s chemical potential. Electrostatic or electrochemical gating of graphene in the proposed structure provides dynamic control of the Fano-like resonance of the grating, suggesting new opportunities for the design of tunable photonic and optoelectronic devices at infrared wavelengths.
Bio-inspired Dielectric Resonator Antennas (DRAs) are engaging more and more attention from the s... more Bio-inspired Dielectric Resonator Antennas (DRAs) are engaging more and more attention from the scientific community due to their exceptional wideband characteristic, which is especially desirable for the implementation of 5G communications. Nonetheless, since these antennas exhibit peculiar geometries in their micro-features, high dimensional accuracy must be accomplished via the selection of the most suitable fabrication process. In this study, the challenges to the manufacturing process presented by the wideband Spiral shell Dielectric Resonator Antenna (SsDRA), based on the Gielis superformula, are addressed. Three prototypes, made of three different photopolymer resins, were manufactured by bottom-up micro-Stereolithography (SLA). This process allows to cope with SsDRA’s fabrication criticalities, especially concerning the wavy features characterizing the thin spiral surface and the micro-features located in close proximity to the spiral origin. The assembly of the SsDRAs with ...
Through the years, inspiration from nature has taken the lead for technological development and i... more Through the years, inspiration from nature has taken the lead for technological development and improvement. This concept firmly applies to the design of the antennas, whose performances receive a relevant boost due to the implementation of bio-inspired geometries. In particular, this idea holds in the present scenario, where antennas working in the higher frequency range (5G and mm-wave), require wide bandwidth and high gain; nonetheless, ease of fabrication and rapid production still have their importance. To this aim, polymer-based 3D antennas, such as Dielectric Resonator Antennas (DRAs) have been considered as suitable for fulfilling antenna performance and fabrication requirements. Differently from numerous works related to planar-metal-based antenna development, bio-inspired DRAs for 5G and mm-wave applications are at their beginning. In this scenario, the present paper proposes the analysis and optimization of a bio-inspired Spiral shell DRA (SsDRA) implemented by means of G...
We report on the numerical simulations and experimental validation of a microwave planar sensor b... more We report on the numerical simulations and experimental validation of a microwave planar sensor based on two coupled rings operating in the 4–6 GHz range. The fabricated sensor is used to characterize the dielectric permittivity of vegetable oils. We optimized the geometrical parameters in order to improve the overlap between the oil samples under study and the electric field. The experimental results showed an excellent match with the simulation results. The fabricated sensor allowed to retrieve the oil permittivity with a sensitivity of about 35 MHz per permittivity unit in the frequency range of interest. This paves the way to the realization of compact and sensitive sensors for a wide plethora of fields ranging from industry and food to chemistry and biology.
In this study, we present a two-dimensional dielectric grating which allows achieving high absorp... more In this study, we present a two-dimensional dielectric grating which allows achieving high absorption in a monolayer graphene at visible and near-infrared frequencies. Dielectric gratings create guided-mode resonances that are exploited to effectively couple light with the graphene layer. The proposed structure was numerically analyzed through a rigorous coupled-wave analysis method. Effects of geometrical parameters and response to the oblique incidence of the plane wave were studied. Numerical results reveal that light absorption in the proposed structure is almost insensitive to the angle of the impinging source over a considerable wide angular range of 20°. This may lead to the development of easy to fabricate and experimentally viable graphene-based absorbers in the future.
In this paper, we numerically and experimentally demonstrate how to modulate the amplitude and ph... more In this paper, we numerically and experimentally demonstrate how to modulate the amplitude and phase of a microwave ring resonator by means of few-layers Chemical Vapour Deposition (CVD) graphene. In particular, both numerical and experimental results show a modulation of about 10 dB and a 90 degrees-shift (quadrature phase shift) when the graphene sheet-resistance is varied. These findings prove once again that graphene could be efficiently exploited for the dynamically tuning and modulation of microwave devices fostering the realization of (i) innovative beam-steering and beam-forming systems and (ii) graphene-based sensors.
ABSTRACT In this paper we propose a tunable notch filter based on an index confined photonic band... more ABSTRACT In this paper we propose a tunable notch filter based on an index confined photonic band gap waveguide. Properly designed periodic corrugated overlay allows the dropping of the electromagnetic wave at a given wavelength. The tunability is reached by exploiting the electroclinic effect of the smectic-A* liquid crystals. All numerical results are obtained by a computer code based on bidirectional beam propagation method using the method of lines. INTRODUCTION The growing interest about photonic crystals in the recent years is mainly due to their capability of modifying the flow of light, allowing the electromagnetic wave at some frequencies to pass through the periodic structures or forbidding other frequencies propagation, thus forming a photonic band gap (PBG) in specific frequency range. An optical PBG structure is characterised by a monodimensional, or two-dimensional, or three-dimensional periodic permittivity so that a light beam which passes through it, reflects and transmits itself many times and it can be propagated or stopped [1-4]. For many applications it is advantageous to obtain some degree of tunability of the basic characteristics and this occurrence is usually obtained through the electro-optic effects. A possibility of performing very interesting figures of tuning, recently tested on PBG devices, is offered by the use of self assembling dielectrics infiltrated with liquid crystals (LC) [5]. The aim of this paper is devoted to the construction of infiltrated liquid crystal photonic crystals (ILCPC) and to the demonstration of electric tuning of the photonic band gap. What it makes liquid crystals attractive for optical applications is mainly the large variety of potential interactions [6] which exploit electro-optic, magneto-optic and acousto-optic effects, some of these having very large strength. As an example, the electro-optic coefficient strength of a nematic liquid crystals is orders of magnitude larger than that of the best electro-optic solid material. Moreover, it is well known that the use of LC in conjunction with optical waveguides for switching light allows to obtain compact devices characterised by a very short switching length [7]. In a previous paper [8] we showed how changing the kind of employed LC, the same self-assembled threedimensional (3D) PBG structure, consisting of layers of square rods, joined by vertical posts, can act as a switch or a continuous tunable filter. The choice of the liquid crystal depends on the operation function to be performed: so the fast and bistable molecular switching of the ferroelectric smectic C* 3M2CPOOB was exploited for the first application, whereas for the second application, the electro-clinic effect, peculiar of the chiral orthogonal smectic A* ZLI4237100, was used. In this last case, the tilt angle is allowed to be continuously controlled from zero to some practical value and consequently to obtain a tunable band-structure when the periodic lattice is infiltrated with the liquid crystal. In this paper we propose a tunable notch filter based on a index confined one dimensional photonic band gap (IC-1D-PBG) waveguide. NUMERICAL RESULTS The structure under examination is depicted in Fig.1. The waveguide consists of a Si 3 N 4 layer d g =500 nm thick having refractive index n g =2, deposited onto SiO 2 substrate (n s =1.45), wavelength λ µm; the superstrate is air. A periodic corrugated overlay constituted by a finite number of N alternating layers of air and Si 3 N 4 is introduced, in order to obtain a one-dimensional periodic structure. The tooth height h=120 nm, the width of the air grooves is w 1 =444 nm and the width of the Si 3 N 4 teeth is w 2 =10 nm corresponding to a total spatial period Λ nm.
We investigate nonlinear properties of a one-dimensional photonic crystal with a graphene-based d... more We investigate nonlinear properties of a one-dimensional photonic crystal with a graphene-based defect, and show that the field enhancement provided by the photonic crystal cavity enhances third harmonic generation and lowers the threshold of nonlinear processes.
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Papers by Antonella D'Orazio