Abstract-Terahertz polarization splitter based on a dual-elliptical-core polymer fiber

Terahertz polarization splitter based on a dual-elliptical-core polymer fiber

Hongzhi Chen, Guofeng Yan, Erik Forsberg, and Sailing He

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-23-6236

A terahertz polarization splitter based on a dual-elliptical-core polymer fiber is proposed and theoretically optimized. Dual-elliptical cores with subwavelength-scale diameters are independently suspended within a fiber, which not only support two orthogonal polarization modes, being single-mode guided with low absorption losses, but also allow them to switch from one core to the other, with different coupling lengths. As a consequence, the two polarizations can be easily separated by choosing a suitable transmission length at a desired operation frequency. The transmission modes, coupling lengths for x- and y-polarizations, as well as the performance of the proposed polarization splitter at a center-frequency of 0.6 THz are investigated and numerically analyzed. A 1.43 cm long splitter with an ultralow loss of 0.4 dB, a high extinction ratio better than −10  dB and a bandwidth of 0.02 THz is achieved.

© 2016 Optical Society of America

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Abstract-Silk Foam Terahertz Waveguides

1. Hichem Guerboukha¹, 
2. Guofeng Yan²,
3. Olga Skorobogata³ and
4. Maksim Skorobogatiy^1,*

Article first published online: 11 SEP 2014

http://onlinelibrary.wiley.com/doi/10.1002/adom.201400228/abstract

DOI: 10.1002/adom.201400228

Fabrication and characterization in the THz frequency range of silk foams and silk foam-based waveguides using lyophilisation and casting techniques are reported. The lack of biocompatible and biofriendly waveguides for low-loss, low-dispersion guidance of THz waves motivates the work for applications in remote and stand-off sensing in biomedical and agro-alimentary industries. Silk foams produced are 94% porous. Optical characterization is carried out using THz time-domain spectroscopy. The cutback measurements of foam samples show that the foam refractive index is close to that of air (). Silk foam losses scale quadratically with frequency (), being one order of magnitude smaller than those of solid silk. As an example of a basic guided wave device, fabrication and optical characterization of 10 cm-long, 5 mm-diameter step-index THz fibers having silk foam in the core and air in the cladding is demonstrated. Cutback measurements confirm that in the mid-THz spectral range, step-index fibers operate effectively in a single mode regime. Effective refractive index and propagation loss at frequencies higher that 0.2 THz are close to that of a silk foam from which the fiber core is made. At the same time, at these frequencies, modal group velocity dispersion is smaller than