Terahertz polarization-maintaining subwavelength dielectric waveguides

Abstract

A terahertz (THz) birefringent waveguide, steering the polarization state of guided modes, is one of the basic components in polarization-sensitive THz systems. In this paper, we propose subwavelength dielectric waveguides with rectangular- and elliptical-core shapes to achieve high birefringence in the THz regime. We implement numerical models to analyze the impact of structural parameters on polarization-maintaining guidance, followed by the frequency dependent propagation performances. Operating at 0.3 THz, the modal birefringence can be of the order of 10−3 or even higher, while the losses of two orthogonally polarized modes are less than 0.088 dB cm−1. Further simulations indicate the waveguides are insensitive to bends (bending radius of 5 mm), and the waveguide coupling efficiency could be greater than 0.9 if a linearly polarized Gaussian beam input is exploited.

Optimization of strip-based hybrid plasmonic terahertz waveguide with distributed Bragg reflector layers

“…all depend on the structure of the waveguide. The polarization stability of the proposed DBR based hybrid THz waveguide is highly dependent on its birefringence, can be explained 23 , 32 , 33 as B(λ)=[neff(x)−neff(y)],where the neff(x) and neff(y) are the effective refractive index of x and y polarized modes, respectively 23 , 32 , 33 …”

“…They have provided high birefringence up to 0.0525, low absorption loss value of 0.04 22 . In 2018, Li et al 23 . numerically investigated subwavelength dielectric waveguides with rectangular and elliptical core shapes and achieved high birefringence at 0.3 THz and dispersion value is 12 ps/THz/cm 23 .…”

“…The THz range in birefringent-based waveguides are used in the THz time domain spectroscopy and biological sensing 22 – 25 …”

Dispersion Limited versus Power Limited Terahertz Transmission Links Using Solid Core Subwavelength Dielectric Fibers

“…Alternatively, by selecting proper dielectric materials with low absorption loss (Teflon, polyethylene, polypropylene, cyclic olefin copolymer to name a few) and engineering the waveguide structure to expel the mode into the low-loss dry air region, highly efficient THz waveguides can be demonstrated [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. In general, dielectric THz waveguides or polymer microwave fibers (PMF) fall under one of the three main categories: hollow core waveguides (antiresonant reflecting optical waveguides (ARROW) or photonic bandgap (PBG) waveguides) [14][15][16][17][18][19][20], porous core waveguides (that use total internal reflection (TIR) or PBG guidance) [21][22][23][24][25] and solid core waveguides (TIR guidance) [26][27][28][29]. In the hollow core dielectric tube fibers, the finite thickness of a thin tubular cladding determines the bandwidth of the low-loss ARROW guidance regime, while such waveguides are generally multimode and can support many core and cladding modes.…”

“…In order to minimize the transmission loss, one usually resorts to either subwavelength core dielectric fibers which are simple rod-in-air fibers or rod-in-foam fibers [27,41] or small solid-core photonic crystal fibers (PCF) with porous claddings [42]. The rod-in-air/foam THz fibers with subwavelength size cores offer low loss and low dispersion guidance as large fraction of the modal fields in such waveguides is guided in the low loss air or foam regions [27][28][29]41]. In such fibers, scattering from inhomogeneities along the fiber length such as diameter variation, micro and macro bending, material density variation.…”