Low loss, low dispersion and highly birefringent terahertz porous fibers

Fabrication and characterization of porous-core honeycomb bandgap THz fibers

“…One strategy first demonstrated by Chen et al is to use a subwavelength core surrounded by an air cladding [7,8]. In order to further reduce the loss, a porous structure of sub-wavelength holes can be introduced into the already sub-wavelength solid core of the fiber [10][11][12][13][14][28][29][30], as first predicted numerically by Hassani et al [10,28] and then demonstrated by Dupuis et al [29] and later Atakaramians et al [13]. Due to the boundary conditions in the electric flux density the refractive index step between material and air in the sub-wavelength holes pushes the field into the lower index holes, thereby increasing the fraction of power in air and reducing the absorption losses [30].…”

THz porous fibers: design, fabrication and experimental characterization

“…These fibers are air-clad fibers with diameters less than or comparable to the operating wavelengths (≤ 600 μm) with sub-wavelength features in the core, which allow low loss propagation and improved confinement of the field compared to microwires [1]. It is also theoretically demonstrated [10] that porous fibers have a smaller decrease in the group velocity, i.e. lower dispersion, relative to microwires.…”

Direct probing of evanescent field for characterization of porous terahertz fibers

“…[1][2][3] Porous polymer fibers-air-clad fibers with subwavelength features embedded within the core-have been identified as a means of achieving low loss, low dispersion and high birefringence for guiding the THz pulses. [4][5][6] Maintaining the polarization of the propagating field in THz waveguides-by using asymmetrical subwavelength air holes 6,7 -makes these fibers a good substitute for free-space, where the polarization state of the THz field is always preserved. Two types of porous fibers, i.e., with symmetrical and asymmetrical features, have been fabricated exploiting the extrusion technique.…”