Research Of Optical Filter Based On Ag Micro/nano-structure Array

Plasmonic optical filter has many advantages like small size beating diffraction limit,wide tunability,durable optical characteristics in extreme environment,integration compatibility with devices.For commercial applications,device performance should be improved to beat technical solutions now existing and drastic reduction in micro/nano structures fabrication is required.To solve these problems,series of research is carried out.Firstly,researches are carried out to explore high performance plasmonic optical filter.,Color filter is the representation of plasmonic optical filter and have the most promising applications.We have designed a sub-micrometer one dimensional grating in an ultra-thin Ag film on glass substrate.The effects of film thickness and grating period on color filter behaviors of the device have been studied.Based on obtained results,the relationship of the wavelength of transmission minima with film thickness and grating period was derived.This equation is tested with series of color filters that are fabricated in lab,and the experimental results indicates that it is very powerful for guiding the design of one dimensional grating color filter device.The obtained filter has characteristics like simple structure,high transmission,high resolution and polarization-dependent.Then,TE/TM polarization-independent plasmonic subtractive color filters are studied.We have designed a two dimensional ultrathin Ag nanodisks plasmonic subtractive color filter with high transmission(up to 70%)in the visible spectral region by employing extraordinary low transmission phenomenon.The dependences of color filtering behaviors on thickness and period of nanodisks have been systematically investigated in both simulations and experiments.Then structural parameters are optimized to get color filters needed.The proposed TE/TM polarization-independent plasmonic color filters with small feature size and high transmission over visible spectral band are promising for digital imaging,information storage and sensing.Next,a new type of bilayer grating optical filter working in near-infrared regime is designed.It works both in band-reject mode and band-pass mode.The rejection band in near-infrared regime is demonstrated numerically and experimentally in reflection spectra and the pass band in near-infrared regime is also demonstrated numerically in transmission spectra.Filtering behaviors under various conditions were studied.The obtained results revealed that this band-reject filter with circle pore using Ag as the metal film exhibited broad rejection band(more than 500 nm),and the rejection band was strongly influenced by structural parameters.Three band-reject filters were experimentally fabricated and test.They are proved to be in good agreement with simulations.At the same time,we also find three pass-band filters with promising applications from simulation.Although there are many Ag nano-particles about tens of nanometers covering PMMA wall in the hole,which leads to high absorption,much lower transmission than simulation and normal reflection,this optical filter fabricated by sputtering can be certainly used as a new type perfect absorber as the absorption is quite high.Moreover,simulation results are meaningful to the fabrication of band-pass filter with methods that may be proposed in future as a guideline.The newly-designed band-reject filter containing only one ultrathin metal film about tens of nanometers,one dielectric layer and substrate is superior to previously reported band-reject filters in terms of broad rejection band,simple structure and high tunability in the near-infrared spectral region.Lastly,as to the method for fabrication of large area plasmonic nanostructure,we improve the setup for preparation of honey-comb patterned polymer film using the breath-figure method.By making the airflow more stable and humid,the improved setup facilitated the formation of films,on which pores are relatively large,with higher regularity,better reproducibility,and larger area of honeycomb structures.Then a lift-off process is carried out with the prepared films.We have got some valuable experiences which are meaningful to the preparation of films with small pores and the transfer for micro/nano structures using these films as templates.