We propose a novel concept of designing silicon photonics metamaterials for perfect near-infrared light absorption.The study's emphasis is an in-depth investigation of various physical mechanisms behind the^100%ul...We propose a novel concept of designing silicon photonics metamaterials for perfect near-infrared light absorption.The study's emphasis is an in-depth investigation of various physical mechanisms behind the^100%ultranarrowband record peak absorptance of the designed structures,comprising an ultrathin silicon absorber.The electromagnetic power transport,described by the Poynting vector,is innovatively explored,which shows combined vortex and crossed-junction two-dimensional waveguide-like flows as outcomes of optical field singularities.These flows,though peculiar for each of the designed structures,turn out to be key factors of the perfect resonant optical absorption.The electromagnetic fields show tight two-dimensional confinement:a sharp vertical confinement of the resonant-cavity type combined with a lateral metasurface supported confinement.The siliconabsorbing layer and its oxide environment are confined between two subwavelength metasurfaces such that the entire design is well compatible with silicon-on-insulator microelectronics.The design concept and its outcomes meet the extensive challenges of ultrathin absorbers for minimum noise and an ultra-narrowband absorptance spectrum,while maintaining an overall very thin structure for planar integration.With these materials and such objectives,the proposed designs seem essential,as standard approaches fail,mainly due to a very low silicon absorption coefficient over the near-infrared range.Tolerance tests for fabrication errors show fair tolerability while maintaining a high absorptance peak,along with a controllable deviation off the central-design wavelength.Various applications are suggested and analyzed,which include but are not limited to:efficient photodetectors for focal plane array and on-chip integrated silicon photonics,high-precision spectroscopic chemical and angular-position sensing,and wavelength-division multiplexing.展开更多
We have discovered a strong increase in the intensity of the chemiluminescence of a luminol flow and a dramatic modification of its spectral shape in the presence of metallic nanoparticles.We observed that pumping gol...We have discovered a strong increase in the intensity of the chemiluminescence of a luminol flow and a dramatic modification of its spectral shape in the presence of metallic nanoparticles.We observed that pumping gold and silver nanoparticles into a microfluidic device fabricated in polydimethylsiloxane prolongs the glow time of luminol.We have demonstrated that the intensity of chemiluminescence in the presence of nanospheres depends on the position along the microfluidic serpentine channel.We show that the enhancement factors can be controlled by the nanoparticle size and material.Spectrally,the emission peak of luminol overlaps with the absorption band of the nanospheres,which maximizes the effect of confined plasmons on the optical density of states in the vicinity of the luminol emission peak.These observations,interpreted in terms of the Purcell effect mediated by nano-plasmons,form an essential step toward the development of microfluidic chips with gain media.Practical implementation of the discovered effect will include improving the detection limits of chemiluminescence for forensic science,research in biology and chemistry,and a number of commercial applications.展开更多
文摘We propose a novel concept of designing silicon photonics metamaterials for perfect near-infrared light absorption.The study's emphasis is an in-depth investigation of various physical mechanisms behind the^100%ultranarrowband record peak absorptance of the designed structures,comprising an ultrathin silicon absorber.The electromagnetic power transport,described by the Poynting vector,is innovatively explored,which shows combined vortex and crossed-junction two-dimensional waveguide-like flows as outcomes of optical field singularities.These flows,though peculiar for each of the designed structures,turn out to be key factors of the perfect resonant optical absorption.The electromagnetic fields show tight two-dimensional confinement:a sharp vertical confinement of the resonant-cavity type combined with a lateral metasurface supported confinement.The siliconabsorbing layer and its oxide environment are confined between two subwavelength metasurfaces such that the entire design is well compatible with silicon-on-insulator microelectronics.The design concept and its outcomes meet the extensive challenges of ultrathin absorbers for minimum noise and an ultra-narrowband absorptance spectrum,while maintaining an overall very thin structure for planar integration.With these materials and such objectives,the proposed designs seem essential,as standard approaches fail,mainly due to a very low silicon absorption coefficient over the near-infrared range.Tolerance tests for fabrication errors show fair tolerability while maintaining a high absorptance peak,along with a controllable deviation off the central-design wavelength.Various applications are suggested and analyzed,which include but are not limited to:efficient photodetectors for focal plane array and on-chip integrated silicon photonics,high-precision spectroscopic chemical and angular-position sensing,and wavelength-division multiplexing.
基金support from the EPSRC established career fellowshipsupport from the BGU(Israel)Outstanding Woman in Science Award。
文摘We have discovered a strong increase in the intensity of the chemiluminescence of a luminol flow and a dramatic modification of its spectral shape in the presence of metallic nanoparticles.We observed that pumping gold and silver nanoparticles into a microfluidic device fabricated in polydimethylsiloxane prolongs the glow time of luminol.We have demonstrated that the intensity of chemiluminescence in the presence of nanospheres depends on the position along the microfluidic serpentine channel.We show that the enhancement factors can be controlled by the nanoparticle size and material.Spectrally,the emission peak of luminol overlaps with the absorption band of the nanospheres,which maximizes the effect of confined plasmons on the optical density of states in the vicinity of the luminol emission peak.These observations,interpreted in terms of the Purcell effect mediated by nano-plasmons,form an essential step toward the development of microfluidic chips with gain media.Practical implementation of the discovered effect will include improving the detection limits of chemiluminescence for forensic science,research in biology and chemistry,and a number of commercial applications.
