Guofeng Yan

Interferometric fiber-optic bending/nano-displacement sensor using plastic dual-core fiber

We demonstrate an interferometric fiber-optic bending/nano-displacement sensor based on a plastic dual-core fiber. The light coupled into the two fiber cores is first guided along the fiber, and then reflected by the mirror coated at the fiber end. Reflected light coming out of the fiber produces interference that shifts as the fiber bends. The interference shift is interrogated using a slit and a photodetector. The resolution of our sensor is ∼3×10(-4) m(-1) for sensing the bending curvature, and ∼70 nm for sensing the displacement.

Resonant THz sensor for paper quality monitoring using THz fiber Bragg gratings.

THz Bragg gratings were fabricated by using CO2 laser inscription. The simulated and experimental results demonstrate potential of such gratings in paper thickness monitoring, with experimental spectral sensitivities of ~ -0.67 GHz / 10 μm.

Low-loss terahertz waveguide Bragg grating using a two-wire waveguide and a paper grating

We propose a low-loss terahertz waveguide Bragg grating (TWBG) fabricated using a plasmonic two-wire waveguide and a micromachined paper grating for potential applications in terahertz (THz) communications. Two TWBGs were fabricated with different periods and lengths. Transmission spectra of these TWBGs show 16 dB loss and 14 dB loss in the middle of their respective stop bands at 0.637 and 0.369 THz, with Q factors of 142 and 105, respectively. Insertion loss of 1-4 dB in the whole 0.1-0.7 THz region was also measured. Finally, TWBG modal dispersion relations, modal loss, and field distributions were studied numerically, and low-loss, high-coupling-efficiency operation of TWBGs was confirmed.

Silk foam terahertz waveguides

Silk foam-based terahertz waveguides are fabricated using lyophilisation and casting techniques. This work is motivated by the lack of biocompatible waveguides for low-loss guidance of THz for applications in remote sensing in biomedical and agro-alimentary industries.

THz Bragg gratings by CO2 laser inscription and their application in paper quality monitoring

THz Bragg gratings were fabricated by using CO2 laser inscription. The simulated and experimental results demonstrate potential of such gratings in paper thickness monitoring, with experimental spectral sensitivities of ~ -0.8 GHz / 10 μm.