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Papers by Maurizio Giardina

Research paper thumbnail of Practical Quantum Cryptography: The Q-KeyMaker

In the next years the data transmission connections will constitute one of the principal tools of... more In the next years the data transmission connections will constitute one of the principal tools of communication among cities, enterprises and public administration. With their enhanced connectivity, the systems and nets of information are now exposed to an increased vulnerability and new safety problems are emerging. Insofar Quantum Key Distribution (QKD) has matured to real world applications and can enhance the safety of the communication nets. In this paper we present the QKD network designed and implemented by Selex-SI and we give an overview of the obtained results.

Research paper thumbnail of Mapping the nonlinear optical susceptibility by noncollinear second-harmonic generation

Optics Letters, 2009

We present a method, based on noncollinear second harmonic generation, to evaluate the non-zero e... more We present a method, based on noncollinear second harmonic generation, to evaluate the non-zero elements of the nonlinear optical susceptibility. At a fixed incidence angle, the generated signal is investigated by varying the polarization state of both fundamental beams. The resulting polarization charts allows to verify if Kleinman symmetry rules can be applied to a given material or to retrieve the absolute value of the nonlinear optical tensor terms, from a reference measurement. Experimental measurements obtained from Gallium Nitride layers are reported. The proposed method does not require an angular scan thus is useful when the generated signal is strongly affected by sample rotation

Research paper thumbnail of Practical Quantum Cryptography: the Q-KeyMaker

In the next years the data transmission connections will constitute one of the principal tools of... more In the next years the data transmission connections will constitute one of the principal tools of communication among cities, enterprises and public administration. With their enhanced connectivity, the systems and nets of information are now exposed to an increased vulnerability and new safety problems are emerging. Insofar Quantum Key Distribution (QKD) has matured to real world applications and can enhance the safety of the communication nets. In this paper we present the QKD network designed and implemented by Selex-SI and we give an overview of the obtained results.

Research paper thumbnail of Bacteriorhodopsin: Tunable Optical Nonlinear Magnetic Response

We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) u... more We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) under "off resonance" femtosecond (fs) pulse excitation, by detecting the polarization map of the noncollinear second harmonic signal of an oriented BR film, as a function of the input beam power. BR is a light-driven proton pump with a unique photochemistry initiated by the all trans retinal chromophore embedded in the protein. An elegant application of this photonic molecular machine has been recently found in the new area of optogenetics, where genetic expression of BR in brain cells conferred a light responsivity to the cells enabling thus specific stimulation of neurons. The observed strong tunable magnetic nonlinear response of BR might trigger promising applications in the emerging area of pairing optogenetics and functional magnetic resonance imaging susceptible to provide an unprecedented complete functional mapping of neural circuits.

Research paper thumbnail of Orbital angular momentum in noncollinear second-harmonic generation by off-axis vortex beams

Journal of The Optical Society of America, 2011

We experimentally study the behavior of orbital angular momentum (OAM) of light in a noncollinear... more We experimentally study the behavior of orbital angular momentum (OAM) of light in a noncollinear second harmonic generation (SHG) process. The experiment is performed by using a type I BBO crystal under phase matching conditions with femtosecond pumping fields at 830 nm. Two specular off-axis vortex beams carrying fractional orbital angular momentum at the fundamental frequency (FF) are used. We analyze the behavior of the OAM of the SH signal when the optical vortex of each input field at the FF is displaced from the beam's axis. We obtain different spatial configurations of the SH field, always carrying the same zero angular momentum.

Research paper thumbnail of Nonlinear optical properties of Bacteriorhodopsin by nonlinear ellipsometry

Multilayer Langmuir^Blodgett films of bacteriorhodopsin were prepared and their nonlinear optical... more Multilayer Langmuir^Blodgett films of bacteriorhodopsin were prepared and their nonlinear optical properties were investigated.

Research paper thumbnail of Optical polarization based logic functions (XOR or XNOR) with nonlinear Gallium nitride nanoslab

Optics Express, 2009

We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmon... more We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. The polarization of the noncollinear generated beam is a function of the polarization of both pump beams, thus we experimentally investigated all possible polarization combinations, evidencing that only some of them are allowed and that the nonlinear interaction of optical signals behaves as a polarization based XOR. The experimental results show the peculiarity of the nonlinear optical response associated with noncollinear excitation, and are explained using the expression for the effective second order optical nonlinearity in noncollinear scheme.

Research paper thumbnail of Optical logic functions with nonlinear Gallium nitride nanoslab

A scheme of XOR/XNOR logic gate is presented, based on non phase-matched noncollinear second harm... more A scheme of XOR/XNOR logic gate is presented, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. A characterization of the nonlinear material is also presented by means of non-collinear scheme.

Research paper thumbnail of Practical Quantum Cryptography: The Q-KeyMaker

In the next years the data transmission connections will constitute one of the principal tools of... more In the next years the data transmission connections will constitute one of the principal tools of communication among cities, enterprises and public administration. With their enhanced connectivity, the systems and nets of information are now exposed to an increased vulnerability and new safety problems are emerging. Insofar Quantum Key Distribution (QKD) has matured to real world applications and can enhance the safety of the communication nets. In this paper we present the QKD network designed and implemented by Selex-SI and we give an overview of the obtained results.

Research paper thumbnail of Mapping the nonlinear optical susceptibility by noncollinear second-harmonic generation

Optics Letters, 2009

We present a method, based on noncollinear second harmonic generation, to evaluate the non-zero e... more We present a method, based on noncollinear second harmonic generation, to evaluate the non-zero elements of the nonlinear optical susceptibility. At a fixed incidence angle, the generated signal is investigated by varying the polarization state of both fundamental beams. The resulting polarization charts allows to verify if Kleinman symmetry rules can be applied to a given material or to retrieve the absolute value of the nonlinear optical tensor terms, from a reference measurement. Experimental measurements obtained from Gallium Nitride layers are reported. The proposed method does not require an angular scan thus is useful when the generated signal is strongly affected by sample rotation

Research paper thumbnail of Practical Quantum Cryptography: the Q-KeyMaker

In the next years the data transmission connections will constitute one of the principal tools of... more In the next years the data transmission connections will constitute one of the principal tools of communication among cities, enterprises and public administration. With their enhanced connectivity, the systems and nets of information are now exposed to an increased vulnerability and new safety problems are emerging. Insofar Quantum Key Distribution (QKD) has matured to real world applications and can enhance the safety of the communication nets. In this paper we present the QKD network designed and implemented by Selex-SI and we give an overview of the obtained results.

Research paper thumbnail of Bacteriorhodopsin: Tunable Optical Nonlinear Magnetic Response

We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) u... more We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) under "off resonance" femtosecond (fs) pulse excitation, by detecting the polarization map of the noncollinear second harmonic signal of an oriented BR film, as a function of the input beam power. BR is a light-driven proton pump with a unique photochemistry initiated by the all trans retinal chromophore embedded in the protein. An elegant application of this photonic molecular machine has been recently found in the new area of optogenetics, where genetic expression of BR in brain cells conferred a light responsivity to the cells enabling thus specific stimulation of neurons. The observed strong tunable magnetic nonlinear response of BR might trigger promising applications in the emerging area of pairing optogenetics and functional magnetic resonance imaging susceptible to provide an unprecedented complete functional mapping of neural circuits.

Research paper thumbnail of Orbital angular momentum in noncollinear second-harmonic generation by off-axis vortex beams

Journal of The Optical Society of America, 2011

We experimentally study the behavior of orbital angular momentum (OAM) of light in a noncollinear... more We experimentally study the behavior of orbital angular momentum (OAM) of light in a noncollinear second harmonic generation (SHG) process. The experiment is performed by using a type I BBO crystal under phase matching conditions with femtosecond pumping fields at 830 nm. Two specular off-axis vortex beams carrying fractional orbital angular momentum at the fundamental frequency (FF) are used. We analyze the behavior of the OAM of the SH signal when the optical vortex of each input field at the FF is displaced from the beam's axis. We obtain different spatial configurations of the SH field, always carrying the same zero angular momentum.

Research paper thumbnail of Nonlinear optical properties of Bacteriorhodopsin by nonlinear ellipsometry

Multilayer Langmuir^Blodgett films of bacteriorhodopsin were prepared and their nonlinear optical... more Multilayer Langmuir^Blodgett films of bacteriorhodopsin were prepared and their nonlinear optical properties were investigated.

Research paper thumbnail of Optical polarization based logic functions (XOR or XNOR) with nonlinear Gallium nitride nanoslab

Optics Express, 2009

We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmon... more We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. The polarization of the noncollinear generated beam is a function of the polarization of both pump beams, thus we experimentally investigated all possible polarization combinations, evidencing that only some of them are allowed and that the nonlinear interaction of optical signals behaves as a polarization based XOR. The experimental results show the peculiarity of the nonlinear optical response associated with noncollinear excitation, and are explained using the expression for the effective second order optical nonlinearity in noncollinear scheme.

Research paper thumbnail of Optical logic functions with nonlinear Gallium nitride nanoslab

A scheme of XOR/XNOR logic gate is presented, based on non phase-matched noncollinear second harm... more A scheme of XOR/XNOR logic gate is presented, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. A characterization of the nonlinear material is also presented by means of non-collinear scheme.