Biomedical subjects

Chunshu Zhang

Publications and source records attributed to Chunshu Zhang.

5 recordsLinked to original sources

PubMed2006

Temperature-insensitive fiber Bragg grating dynamic pressure sensing system.

Temperature-insensitive dynamic pressure measurement using a single fiber Bragg grating (FBG) based on reflection spectrum bandwidth modulation and optical power detection is proposed. A specifically designed double-hole cantilever beam is used to provide a pressure-induced axial strain gradient along the sensing FBG and is also used to modulate the reflection bandwidth of the grating. The bandwidth modulation is immune to spatially uniform temperature effects, and the pressure can be unambiguously determined by measuring the reflected optical power, avoiding the complex wavelength interrogation system. The system acquisition time is up to 85 Hz for dynamic pressure measurement, and the thermal fluctuation is kept less than 1.2% full-scale for a temperature range of -10 degrees C to 80 degrees C.

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PubMed2006

Modal cutoff properties in germanium-doped photonic crystal fiber.

The germanium-doped photonic crystal fiber (PCF) has some characteristics that differentiate it from pure-silica PCF for a germanium element being doped in the core, such as the intensified nonlinearity, the enhanced photosensitivity, and so on. To pave the way for the application of the Ge-doped PCF successfully, it is necessary to study its properties. We investigated the modal cutoff properties of Ge-doped PCF quantitatively by using the beam propagation method. The numerical results show that the effective refractive indices and the normalized frequency V of Ge-doped PCF not only depend on the normalized pitch delta/lambda but also depend on the normalized hole size d/delta, the modal cutoff boundary for the single mode-multimode of the Ge-doped PCF shift to the low d/delta side in contrast to the pure-silica PCF.

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PubMed2005

Tunable highly birefringent photonic bandgap fibers.

A novel tunable highly birefringent photonic bandgap fiber (PBGF) is designed theoretically by filling its air holes with high-index material. The transmission band can be continuously tuned by changing the refractive index of the filling material. Accordingly, the tunable modal birefringence and polarization mode dispersion of the PBGFs are investigated by adjusting the refractive index of the filling material. Furthermore, we have also analyzed the effect of surface modes in the photonic bandgap on the characteristics of the tunable PBGFs. The simulation results show the feasibility of constructing birefringence-tunable photonic crystal fibers and related fiber devices in practical applications.

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PubMed2005

Coupling and decoupling of dual-core photonic bandgap fibers.

Coupling characteristics of dual-core photonic bandgap fibers with triangular photonic crystal cladding are investigated by use of a vector plane-wave expansion method and a vector finite-element method. We demonstrate the eigenmodes and the coupling length for two orthogonal polarizations. A decoupling phenomenon is found at a certain wavelength in this fiber configuration. The decoupling effect is attributed to the effect of surface modes on the eigenmodes. The decoupling wavelength decreases as the ratio of core radius to cladding air-hole pitch increases from 1.05 to 1.15.

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PubMed2005

Transformation of a transmission mechanism by filling the holes of normal silica-guiding microstructure fibers with nematic liquid crystal.

Transformation of an optical transmission mechanism was achieved when the holes of normal silica-guiding microstructure fiber (MF) were filled with nematic liquid crystal (NLC). Moreover, two photonic bandgaps (PBGs) were obtained by using a plane-wave method to create the pattern. The wavelength dependence of the effective mode area, leakage loss, and group velocity dispersion (GVD) has been theoretically investigated by using a full-vector finite-element method with anisotropic perfectly matched layers. The results reveal that the characteristics of the NLC-filled PBG-MFs are particularly wavelength dependent. This research gives a physical insight into the propagation mechanism in MFs and is crucial for future transmission applications.

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