Experimental and numerical study of a broad pass-band low-loss optical metamaterials filter

•A broad pass-band can be achieved over 96% transmittance across the 90.0–105.0 THz.•The well-matched impedance to free space across leads to the ass-band.•A nearly constant effective impedance was observed with a small variation of 3.8%.•The fabricated metamaterial filter can be modulated from a double negative material to a normal material throughout the pass-band.•The pass-band is expanded with w2 increasing or h1 reducing.

We present the simulation, and fabrication of an optical metamaterial filter. It consists of two silver layers and one SU-8 layer perforated with periodic sub-wavelength holes arrays which are prepared by optical lithography. Measured results indicate that a broad pass-band with over 96% transmittance across 90.0–105.0 THz frequency range can be obtained. Effective permeability, permittivity, and impedance are retrieved by applying S parameter retrieval method. These retrieved effective parameters show that the fabricated metamaterial filter can be modulated from a double negative material to a normal material in pass-band. Real parts of effective permeability and permittivity follow a similar slope results in well-matched impedance to free space, which leads to the broad pass-band. Furthermore, effects of nano-hole sidewall length (w2) and thickness of dielectric layer (h1) are experimental surveyed. The pass-band is expanded with w2 increasing or h1 reducing due to the reduced of strength of electromagnetic resonance.