To control second harmonic generation (SHG) in silica-based glasses is crucial for fabricating photonic devices, such as frequency doubling waveguides. Here, we investigated SHG of laser induced nonlinear optical crys...To control second harmonic generation (SHG) in silica-based glasses is crucial for fabricating photonic devices, such as frequency doubling waveguides. Here, we investigated SHG of laser induced nonlinear optical crystals in silica-based glasses, according to writing speed and pulse energy. We observed two regions with different probing laser polarization angular dependence: a) a well-defined cosine-like curve with period of 180° at low pulse energy (0.8 μJ) whatever the writing speed or at high pulse energy (1.4 μJ) with high writing speed (25 μm/s). This is accounted for by a well-defined texture for the nano crystals with their polar axis oriented perpendicular to the writing laser polarization;and b) a double cosine-like curve revealing a second texture of the crystals at high pulse energy (1.4 μJ) with low writing speed (5 μm/s) and with the polar axis oriented closer parallel to the writing laser polarization. Therefore, a SHG dependence on probing laser polarization angle may show high contrast by a correct choice of the writing speed and pulse energy. These results pave the way for elaboration of nonlinear optical devices.展开更多
An object that possesses chirality,that is,having its mirror image not overlayed on itself by rotation and translation,can provide a different optical response to a left-or right-handed circular polarized light.Chiral...An object that possesses chirality,that is,having its mirror image not overlayed on itself by rotation and translation,can provide a different optical response to a left-or right-handed circular polarized light.Chiral nanostructures may exhibit polarization-selective optical properties that can be controlled for micro-to-nano optical element engineering.An attractive way to induce such complex nanostructures in three-dimension in glass is femtosecond laser direct writing.However,the mechanism of femtosecond laser induced chirality remains to be unveiled due to complex physical and chemical processes occurring during the ultrashort light-matter interaction.Here,a phenomenological model is proposed and is built on two-layers phase shifters to account for this laser-induced optical chirality in an initially achiral material(silica glass).This model is based on the observation that femtosecond laser induced nanogratings own two principal contributions to its aggregate birefringent response:a form and a stress-related one.By refining this formalism,a multilayer approach is developed to imprint on demand optical rotation.Values up to+/-60°at 550 nm within an optimal 80μm thickness in silica glass are possible,corresponding to the highest value in a glass to date.These results provide new insights of circular-optical control in micro-nano optical manufacturing and open new opportunities for photonics applications.展开更多
The paper addresses the creation of circular optical properties from a femtosecond laser light beam with a linear polarization in an achiral material(glass)under an orthogonal incidence.In this situation,all aspects o...The paper addresses the creation of circular optical properties from a femtosecond laser light beam with a linear polarization in an achiral material(glass)under an orthogonal incidence.In this situation,all aspects of the experiment are achiral and therefore should not give rise to chiral property creation.From that observation,we propose an interpretation that involves the action of a light-induced torque on the matter carrying a light-induced dielectric moment.We found that a direct current(DC)electric field could be produced in the lattice by the femtosecond laser in our conditions and that a non-collinear dielectric moment is created by a nonlinear effect between the DC electric field and the stress field due to the transformation of the material.We reveal that it is possible to break the chiral symmetry of glass using an intense,ultrashort laser light pulse.展开更多
Grating writing in structured optical fibers is reviewed. Various laser sources have been used including UV and near IR nanosecond and femtosecond lasers, each enabling different material processing regimes. The issue...Grating writing in structured optical fibers is reviewed. Various laser sources have been used including UV and near IR nanosecond and femtosecond lasers, each enabling different material processing regimes. The issue of scattering is modeled through simulation and compared with experiment. Good agreement has been established.展开更多
基金The work has been done in the frame of FLAG(Femtosecond Laser Application in Glasses)consortium project with the support of Agence Nationale pour la Recherche(ANR-09-BLAN-0172-01)The authors extend thanks to China Scholarship Council and UniversitéParis-Sud.
文摘To control second harmonic generation (SHG) in silica-based glasses is crucial for fabricating photonic devices, such as frequency doubling waveguides. Here, we investigated SHG of laser induced nonlinear optical crystals in silica-based glasses, according to writing speed and pulse energy. We observed two regions with different probing laser polarization angular dependence: a) a well-defined cosine-like curve with period of 180° at low pulse energy (0.8 μJ) whatever the writing speed or at high pulse energy (1.4 μJ) with high writing speed (25 μm/s). This is accounted for by a well-defined texture for the nano crystals with their polar axis oriented perpendicular to the writing laser polarization;and b) a double cosine-like curve revealing a second texture of the crystals at high pulse energy (1.4 μJ) with low writing speed (5 μm/s) and with the polar axis oriented closer parallel to the writing laser polarization. Therefore, a SHG dependence on probing laser polarization angle may show high contrast by a correct choice of the writing speed and pulse energy. These results pave the way for elaboration of nonlinear optical devices.
基金Agence Nationale pour la Recherche,FLAG-IR project,grant number ANR-18-CE08-0004-01d CNRS Défi Instrumentation aux Limites,UltraBragg project,Science and Technology Commission of Shanghai Municipality(20JC1415700)+1 种基金Jiafeng Lu acknowledges the China Scholarship Council(CSC)for the funding No.202006890077We greatly acknowledge Dr.Maxime Cavillon for valuable discussions.
文摘An object that possesses chirality,that is,having its mirror image not overlayed on itself by rotation and translation,can provide a different optical response to a left-or right-handed circular polarized light.Chiral nanostructures may exhibit polarization-selective optical properties that can be controlled for micro-to-nano optical element engineering.An attractive way to induce such complex nanostructures in three-dimension in glass is femtosecond laser direct writing.However,the mechanism of femtosecond laser induced chirality remains to be unveiled due to complex physical and chemical processes occurring during the ultrashort light-matter interaction.Here,a phenomenological model is proposed and is built on two-layers phase shifters to account for this laser-induced optical chirality in an initially achiral material(silica glass).This model is based on the observation that femtosecond laser induced nanogratings own two principal contributions to its aggregate birefringent response:a form and a stress-related one.By refining this formalism,a multilayer approach is developed to imprint on demand optical rotation.Values up to+/-60°at 550 nm within an optimal 80μm thickness in silica glass are possible,corresponding to the highest value in a glass to date.These results provide new insights of circular-optical control in micro-nano optical manufacturing and open new opportunities for photonics applications.
基金the support of FP7-PEOPLE-IRSES e-FLAG 247635 from the Agence Nationale pour la Recherche(ANR-09-BLAN-0172-01).
文摘The paper addresses the creation of circular optical properties from a femtosecond laser light beam with a linear polarization in an achiral material(glass)under an orthogonal incidence.In this situation,all aspects of the experiment are achiral and therefore should not give rise to chiral property creation.From that observation,we propose an interpretation that involves the action of a light-induced torque on the matter carrying a light-induced dielectric moment.We found that a direct current(DC)electric field could be produced in the lattice by the femtosecond laser in our conditions and that a non-collinear dielectric moment is created by a nonlinear effect between the DC electric field and the stress field due to the transformation of the material.We reveal that it is possible to break the chiral symmetry of glass using an intense,ultrashort laser light pulse.
文摘Grating writing in structured optical fibers is reviewed. Various laser sources have been used including UV and near IR nanosecond and femtosecond lasers, each enabling different material processing regimes. The issue of scattering is modeled through simulation and compared with experiment. Good agreement has been established.
