Ultrabroad terahertz bandpass filter by hyperbolic metamaterial waveguide

Abstract

We propose and demonstrate an ultrabroad terahertz (THz) bandpass filter (BPF) by integrating two different-sized tapered hyperbolic metamaterial (HMM) waveguides, each of which has wide but different absorption and transmission bands, into a unit cell. With proper structural design of each HMM waveguide to control the absorption and transmission bands, we numerically demonstrate the designed BPF is capable of operating with a broad passband in the THz domain. A typical TM-polarized HMM BPF has a peak transmission of 37% at 3.3 THz with the passband bandwidth of 2.2 THz ranging from 2.97 to 5.17 THz. The co-designed three-dimensional HMM BPF also shows the capability of operating with independence to the polarization of incident light because of the structural symmetry and has sharp bandedge transitions of 22.6 and 17.6 dB/THz to the stop bands, respectively. The presented results here hold great promise for developing practical THz BPF with various applications in THz field.

Terahertz Wideband Filter Based on Sub-Wavelength Binary Simple Periodic Structure

“…As an important part of terahertz functional devices, terahertz broadband filters have important research significance in terahertz technology applications such as medical imaging, security inspection, and product inspection. At present, the main categories of terahertz broadband filters are mainly focused on photonic crystal filters [1], plasma filters [2], and meta-material filters [3][4][5][6][7][8][9]. Photonic crystal filters mainly have terahertz broadband filters with low center-bands and narrow bands with multiple peaks.…”

“…In 2011, Singapore National University et al [4] used a flexible substrate to achieve a broadband filtering effect using polyethylene naphthalate (PEN) as a substrate, overlapping the multi-layer loop structure and fabricating a broadband filter. Among the abovementioned filters, Xuetong Zhou et al [6] designed an ultra-wideband terahertz band-pass filter with a double-cone filter (DCF) with a 3-dB bandwidth of 2.2 THz and a center frequency of about 4.07 THz. The filter's highest transmittance was nearly 37%.…”

Dual-Band Light Absorption Enhancement in Hyperbolic Rectangular Array

“…spectral bands [13][14][15][16][17][18][19][21][22][23][24][25][26][27], and there are only a few studies on selective absorption enhancement of HMMs.…”

“…It has been shown that HMMs can be used to enhance light absorption due to their high-k modes and divergent photonic density of states [4,12]. To date, many efforts have been made to improve light absorption of HMMs with the absorption wavelengths covering the microwave [13], terahertz [14][15][16], infrared [17][18][19][20][21][22] and visible wavelength regions [23][24][25][26][27]. In real applications, selective absorption enhancement is highly desired in fields such as thermal radiation tailoring [28], sensitive detection [29] and sensing [30].…”

“…In real applications, selective absorption enhancement is highly desired in fields such as thermal radiation tailoring [28], sensitive detection [29] and sensing [30]. However, previous studies of HMMs mainly focused on light absorption enhancement in broad spectral bands [13][14][15][16][17][18][19][21][22][23][24][25][26][27], and there are only a few studies on selective absorption enhancement of HMMs.…”