The practical development of compact modern nanophotonic devices relies on the availability of fast and low-cost fabrication techniques applicable to a wide variety of materials and designs.We have engraved a split gr...The practical development of compact modern nanophotonic devices relies on the availability of fast and low-cost fabrication techniques applicable to a wide variety of materials and designs.We have engraved a split grating geometry on stainless steel using femtosecond laser processing.This structure serves as a template to fabricate efficient plasmonic sensors,where a thick gold layer is grown conformally on it.The scanning electron microscope(SEM)images confirm the generation of the split laser-induced periodic spatial structures.The optical reflectance of our sensors shows two dips corresponding to the excitation of surface plasmon resonances(SPRs)at two different wavelengths.Furthermore,the asymmetric shape of these spectral responses reveals a strong and narrow Fano resonance.Our computational electromagnetism models accurately reproduce the reflectivity of the fabricated structure.The spectral responses of both the simulated and fabricated structures are fitted to the Fano model that coherently combines the narrow SPRs with the broad continuum background caused by diffraction.The parameters extracted from the fitting,such as the resonance wavelengths and line widths,are used to evaluate the performance of our device as a refractometric sensor for liquids.The maximum sensitivity and figure of merit are 880 nm/RIU and 80 RIU-1,respectively.Besides the compact design of our sensing device,its performance exceeds the theoretical maximum sensitivity of a classical Kretschmann setup.展开更多
Stainless steel is a basic raw material used in many industries.It can be customized by generating laser-induced periodic surface structure(LIPSS)as subwavelength gratings.Here,we present the capabilities of an LIPSS ...Stainless steel is a basic raw material used in many industries.It can be customized by generating laser-induced periodic surface structure(LIPSS)as subwavelength gratings.Here,we present the capabilities of an LIPSS on stainless steel to modify the polarization state of the reflected radiation at the IR band.These structures have been modeled using the finite element method and fabricated by femtosecond laser processing.The Stokes parameters have been obtained experimentally and a model for the shape has been used to fit the simulated Stokes values to the experimental data.The birefringence of the LIPSS is analyzed to explain how they modify the polarization state of the incoming light.We find the geometry of the subwavelength grating that makes it work as an optical retarder that transforms a linearly polarized light into a circularly polarized wave.In addition,the geometrical parameters of the LIPSS are tuned to selectively absorb one of the components of the incoming light,becoming a linear axial polarizer.Appropriately selecting the geometrical parameters and orientation of the fabricated LIPSS makes it possible to obtain an arbitrary pure polarization state when illuminated by a pure linearly polarized state oriented at an azimuth of 45°.The overall reflectance of these transformations reaches values close to 60%with respect to the incident intensity,which is the same reflectivity obtained for non-nanostructured stainless steel flat surfaces.展开更多
A metallic nanostructured array that scatters radiation toward a thin metallic layer generates surface plasmon resonances for normally incident light. The location of the minimum of the spectral reflectivity serves to...A metallic nanostructured array that scatters radiation toward a thin metallic layer generates surface plasmon resonances for normally incident light. The location of the minimum of the spectral reflectivity serves to detect changes in the index of refraction of the medium under analysis. The normal incidence operation eases its integration with optical fibers. The geometry of the arrangement and the material selection are changed to optimize some performance parameters as sensitivity, figure of merit, field enhancement, and spectral width. This optimization takes into account the feasibility of the fabrication. The evaluated results of sensitivity(1020 nm/RIU)and figure of merit(614 RIU^(-1)) are competitive with those previously reported.展开更多
文摘The practical development of compact modern nanophotonic devices relies on the availability of fast and low-cost fabrication techniques applicable to a wide variety of materials and designs.We have engraved a split grating geometry on stainless steel using femtosecond laser processing.This structure serves as a template to fabricate efficient plasmonic sensors,where a thick gold layer is grown conformally on it.The scanning electron microscope(SEM)images confirm the generation of the split laser-induced periodic spatial structures.The optical reflectance of our sensors shows two dips corresponding to the excitation of surface plasmon resonances(SPRs)at two different wavelengths.Furthermore,the asymmetric shape of these spectral responses reveals a strong and narrow Fano resonance.Our computational electromagnetism models accurately reproduce the reflectivity of the fabricated structure.The spectral responses of both the simulated and fabricated structures are fitted to the Fano model that coherently combines the narrow SPRs with the broad continuum background caused by diffraction.The parameters extracted from the fitting,such as the resonance wavelengths and line widths,are used to evaluate the performance of our device as a refractometric sensor for liquids.The maximum sensitivity and figure of merit are 880 nm/RIU and 80 RIU-1,respectively.Besides the compact design of our sensing device,its performance exceeds the theoretical maximum sensitivity of a classical Kretschmann setup.
基金Ministerio de Economía y Competitividad,European Funds for Regional Development(PID2019-105918GB-I00,RTC2019-007113-3)。
文摘Stainless steel is a basic raw material used in many industries.It can be customized by generating laser-induced periodic surface structure(LIPSS)as subwavelength gratings.Here,we present the capabilities of an LIPSS on stainless steel to modify the polarization state of the reflected radiation at the IR band.These structures have been modeled using the finite element method and fabricated by femtosecond laser processing.The Stokes parameters have been obtained experimentally and a model for the shape has been used to fit the simulated Stokes values to the experimental data.The birefringence of the LIPSS is analyzed to explain how they modify the polarization state of the incoming light.We find the geometry of the subwavelength grating that makes it work as an optical retarder that transforms a linearly polarized light into a circularly polarized wave.In addition,the geometrical parameters of the LIPSS are tuned to selectively absorb one of the components of the incoming light,becoming a linear axial polarizer.Appropriately selecting the geometrical parameters and orientation of the fabricated LIPSS makes it possible to obtain an arbitrary pure polarization state when illuminated by a pure linearly polarized state oriented at an azimuth of 45°.The overall reflectance of these transformations reaches values close to 60%with respect to the incident intensity,which is the same reflectivity obtained for non-nanostructured stainless steel flat surfaces.
基金Funding.Ministerio de Economía y Competitividad(MINECO)(TEC2013-40442)Ministry of Higher Education(MOHE)(missions section)
文摘A metallic nanostructured array that scatters radiation toward a thin metallic layer generates surface plasmon resonances for normally incident light. The location of the minimum of the spectral reflectivity serves to detect changes in the index of refraction of the medium under analysis. The normal incidence operation eases its integration with optical fibers. The geometry of the arrangement and the material selection are changed to optimize some performance parameters as sensitivity, figure of merit, field enhancement, and spectral width. This optimization takes into account the feasibility of the fabrication. The evaluated results of sensitivity(1020 nm/RIU)and figure of merit(614 RIU^(-1)) are competitive with those previously reported.
