We demonstrate theoretically and experimentally the difference between the band compression mechanisms of plasmonic gratings and plasmonic heterogratings.The plasmonic grating can pick out a fixed polarization band-width with changing the incidence angle,while the plasmonic heterograting composed of two different nanograt-ings can pick out a tunable bandwidth with changing the incidence angle and the period ratio of two gratings.The range of the plasmonic resonances of the heterograting is about 30%wider than that of a conventional grating.Thus,the plasmonic heterograting can work efficiently in a wider wavelength range.Moreover,high polarization extinction ratio is achieved in these plasmonic devices.This gives more insights into the mechanisms in plasmonic filters and is helpful to promote the actual applications.
LIN Yuan-HaiZHAI Tian-RuiLIU Hong-MeiZHANG Xin-Ping
Polymeric semiconductors spin-coated onto the photoresist grating form discontinuously distributed flocci,which do not fill grating grooves with nanoscale widths.Thus,the polymer layer neither forms a continuous gain channel nor creates a waveguide that enhances the distributed feedback(DFB)mechanism provided by the grating structures.This is verified by the microscopic and spectroscopic investigations on the topographic surface of the polymer-covered grating as it is etched layer by layer using oxygen plasma.This gives more insights into the mechanisms involved in optically pumped polymer lasers and provides new guidance for constructing DFB lasers.
