We theoretically investigate the electromagnetic response of a novel class of multilayered metamaterials obtained by alternating graphene sheets and dielectric layers,the whole structure not exhibiting a plane of refl...We theoretically investigate the electromagnetic response of a novel class of multilayered metamaterials obtained by alternating graphene sheets and dielectric layers,the whole structure not exhibiting a plane of reflection symmetry along the stacking direction.We show that the electromagnetic response of the structure is characterized by a magneto-electric coupling described by an effective chiral parameter.Exploiting the intrinsic tunability of graphene–light coupling,we prove that one can tune both the dielectric and the chiral electromagnetic response by varying the graphene chemical potential through external voltage gating.展开更多
Optical parametric oscillators are widely used as pulsed and continuous-wave tunable sources for innumerable applications,such as quantum technologies,imaging,and biophysics.A key drawback is material dispersion,which...Optical parametric oscillators are widely used as pulsed and continuous-wave tunable sources for innumerable applications,such as quantum technologies,imaging,and biophysics.A key drawback is material dispersion,which imposes a phase-matching condition that generally entails a complex design and setup,thus hindering tunability and miniaturization.Here we show that the burden of phase-matching is surprisingly absent in parametric microresonators utilizing mono-layer transition-metal dichalcogenides as quadratic nonlinear materials.By the exact solution of nonlinear Maxwell equations and first-principle calculations of the semiconductor nonlinear response,we devise a novel kind of phase-matching-free miniaturized parametric oscillator operating at conventional pump intensities.We find that different two-dimensional semiconductors yield degenerate and non-degenerate emission at various spectral regions due to doubly resonant mode excitation,which can be tuned by varying the incidence angle of the external pump laser.In addition,we show that high-frequency electrical modulation can be achieved by doping via electrical gating,which can be used to efficiently shift the threshold for parametric oscillation.Our results pave the way for the realization of novel ultra-fast tunable micron-sized sources of entangled photons—a key device underpinning any quantum protocol.Highly miniaturized optical parametric oscillators may also be employed in lab-on-chip technologies for biophysics,detection of environmental pollution and security.展开更多
基金the Italian Ministry of Research(MIUR)through the“Futuro in Ricerca”FIRB-grant PHOCOS-RBFR08E7VA and by Progetto DOTE Lombardia.
文摘We theoretically investigate the electromagnetic response of a novel class of multilayered metamaterials obtained by alternating graphene sheets and dielectric layers,the whole structure not exhibiting a plane of reflection symmetry along the stacking direction.We show that the electromagnetic response of the structure is characterized by a magneto-electric coupling described by an effective chiral parameter.Exploiting the intrinsic tunability of graphene–light coupling,we prove that one can tune both the dielectric and the chiral electromagnetic response by varying the graphene chemical potential through external voltage gating.
基金the US Army International Technology Center Atlantic for financial support(Grant No.W911NF-17-1-0505)funding from H2020 QuantERA-Quomplex(grant number 731473)+2 种基金the Templeton foundation(Grant No.58277)PRIN NEMO(reference 2015KEZNYM)funding from the CNR-SPIN(Seed Project,Grant No.B52F17001370005).
文摘Optical parametric oscillators are widely used as pulsed and continuous-wave tunable sources for innumerable applications,such as quantum technologies,imaging,and biophysics.A key drawback is material dispersion,which imposes a phase-matching condition that generally entails a complex design and setup,thus hindering tunability and miniaturization.Here we show that the burden of phase-matching is surprisingly absent in parametric microresonators utilizing mono-layer transition-metal dichalcogenides as quadratic nonlinear materials.By the exact solution of nonlinear Maxwell equations and first-principle calculations of the semiconductor nonlinear response,we devise a novel kind of phase-matching-free miniaturized parametric oscillator operating at conventional pump intensities.We find that different two-dimensional semiconductors yield degenerate and non-degenerate emission at various spectral regions due to doubly resonant mode excitation,which can be tuned by varying the incidence angle of the external pump laser.In addition,we show that high-frequency electrical modulation can be achieved by doping via electrical gating,which can be used to efficiently shift the threshold for parametric oscillation.Our results pave the way for the realization of novel ultra-fast tunable micron-sized sources of entangled photons—a key device underpinning any quantum protocol.Highly miniaturized optical parametric oscillators may also be employed in lab-on-chip technologies for biophysics,detection of environmental pollution and security.
