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Yao H.-Z.,Fuzhou University | Zhong S.,Fuzhou University | Zhong S.,Fujian Key Laboratory of Medical Instrument and Pharmaceutical Technology
IEEE Photonics Journal | Year: 2015

We report the characteristics of a right-handed helically grooved metal wire waveguide. For the helically grooved waveguide, the normal degenerate HE1 spoof surface plasmon polariton (SSPP) mode could be decomposed into two opposite circularly polarized modes, i.e., HE-1 and HE+1 SSPP modes, due to the chirality of helical grooves. The dispersion characteristics of the nondegenerate HE ± 1 SSPP modes were numerically obtained, and their spiral electromagnetic distributions were also presented. It was found that the HE ± 1 modes were circularly polarized; they were also vortex modes and possessed an orbit angular monument. In addition, the focusing characteristics of such waves near the waveguide end were investigated. The distinct advantages, such as a relatively long focusing length and the circular polarization of the chiral HE + 1 SSPP modes, make the helically grooved metal wire waveguide a potential for near-field circular dichroism detection. © 2009-2012 IEEE. Source

Yao H.,Fuzhou University | Zhong S.,Fuzhou University | Zhong S.,Fujian Key Laboratory of Medical Instrument and Pharmaceutical Technology
Optics Express | Year: 2014

We report terahertz surface plasmon resonance (SPR) sensing based on prism-coupling to the spoof surface plasmon polariton (SSPP) mode existing on periodically grooved metal films. It was demonstrated that, except for the fundamental mode of the SSPP, there was also a higher mode SSPP wave when the depth of groove was larger. Both fundamental and high-order modes of SSPP could be used for terahertz sensing. We compared the performance of different modes of SSPP on the sensing sensitivity using both reflection amplitude and phase-jump information. The results indicated that the gap distance between the prism base and the metal film had a significant influence on the reflectivity of SPR sensing by affecting the coupling efficiency of an evanescent wave to an SSPP wave; also, high-order mode SSPP-based sensing had a high sensitivity of up to 2.27 THz/RIU, which nearly doubled the sensitivity of the fundamental mode. The application of high-mode SSPP has enormous potential for ultra-sensitive SPR sensing in the terahertz regime. © 2014 Optical Society of America. Source

Yao H.,Fuzhou University | Zhong S.,Fuzhou University | Zhong S.,Fujian Key Laboratory of Medical Instrument and Pharmaceutical Technology
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2014

The spoof surface plasmon polariton (SPP) effect on the electromagnetic field distribution near the tip of a periodically corrugated metal cylinder-cone probe working at the terahertz regime was studied. We found that radially polarized terahertz radiation could be coupled effectively through a spoof SPP into a surface wave and propagated along the corrugated surface, resulting in more than 20× electric field enhancement near the tip of probe. Multiple resonances caused by the antenna effect were discussed in detail by finite element computation and theoretical analysis of dispersion relation for spoof SPP modes. Moreover, the key figures of merit such as the resonance frequency of the SPP can be flexibly tuned by modifying the geometry of the probe structure, making it attractive for application in an apertureless background-free terahertz near-field microscope. © 2014 Optical Society of America. Source

Luo M.,Fuzhou University | You T.,Fuzhou University | Zhang Q.,Fuzhou University | Zhong J.,Fuzhou University | And 2 more authors.
Journal of Applied Optics | Year: 2015

Based on the balanced detection and stationary wavelet transform (SWT) algorithm, a broadband low coherent white light source with center wavelength of 700 nm was employed to set up a time-domain optical coherence tomography (TDOCT) system in free space. The resolution of the developed OCT system was down to 0.93 μm and it was applied to nondestructive evaluation of plastic sheets and transparent-tape multi-layered thin-film structures. The imaging enhancement methods in the process of OCT images were compared. To resolve the problem of unsatisfactory reconstruction results using current algorithms, the SWT decomposition algorithm was introduced to deal with the OCT images of the multi-layered structures. The experimental results show that this SWT-based method could extract more distinct interface interference signal from the SWT detail coefficients and therefore the interface imaging quality of multi-layered structures could be enhanced. ©, 2015, Editorial Board, Journal of Applied Optics. All right reserved. Source

Zhong J.,Fuzhou University | Zhong S.,Fuzhou University | Zhong S.,Fujian Key Laboratory of Medical Instrument and Pharmaceutical Technology | Zhang Q.,Fuzhou University | Yao L.,Fuzhou University
Optics and Lasers in Engineering | Year: 2015

We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis. © 2014 Elsevier Ltd. Source

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