Abstract
Tunable extraordinary transmission via changing temperature of a porous metallic layer on top of a thin layer of dielectric strontium titanate (STO) was studied. The metallic layer has a through-hole array and each hole has a circular converging-diverging channel (CDC) shape, which induces the excitation of surface plasmon polaritons (SPPs) and then results in a controllable extraordinary optical transmission in the terahertz (THz) frequency range. We used a three-dimensional (3D) finite element method to analyze the transmission characteristics of the structure. Location and magnitude of the transmission peaks can be adjusted by hole size, converging angle, and thicknesses of metal and STO layers. Remarkably, the suggested structure presents a strong transmission dependency on temperature, which offers a new approach to actively and externally tune the transmission. This new design could lead to a family of temperature-sensitive devices working in the THz frequency range, promising in many applications including photonics, nanolithography, imaging, and sensing.
Highlights
The terahertz (THz) frequency band, which lies between domains of microwave electronics and mid infrared optics, has received increasing attentions recently because of its possible applications in fundamental science, new imaging and sensing modalities, and high bandwidth signal processing [1]
This work has generated considerable interests in recent years and led to the development of a new family of optical devices based on subwavelength hole arrays with extraordinary transmission spectra
We have investigated the transmission spectra of metallic hole arrays with different converging-diverging channels combined with a layer of strontium titanate (STO)
Summary
The terahertz (THz) frequency band, which lies between domains of microwave electronics and mid infrared optics, has received increasing attentions recently because of its possible applications in fundamental science, new imaging and sensing modalities, and high bandwidth signal processing [1]. This work has generated considerable interests in recent years and led to the development of a new family of optical devices based on subwavelength hole arrays with extraordinary transmission spectra This unique phenomenon is believed to be due to the SPPs excited at the metal/dielectric interface [7,8,9]. The term “non-linear response” means their optical properties can be controlled by external parameters (temperature, electric or magnetic field, light pulse, etc.) Among these non-linear materials, so called incipient ferroelectric materials [27] such as strontium titanate (SrTiO3, STO) or potassium tantalate (KTaO3, KTO) exhibit a potential to realize the large frequency range and active tuning. The strong transmission dependency on temperature provides us the capability to modulate the transmission without using deformation or replacement—a true active frequency tuning
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