Biomedical subjects

Lifang Xue

Publications and source records attributed to Lifang Xue.

4 recordsLinked to original sources

PubMed2006

Method for enhancing temperature sensitivity of fiber Bragg gratings based on bimetallic sheets.

We designed what is believed to be a novel structure based on bimetallic sheets to enhance temperature sensitivity of fiber Bragg gratings. The two ends of bimetallic sheets were fixed by bolts, and a fiber Bragg grating was longitudinally affixed to one of the sheets whose expansion coefficient was larger than that of the other. The theoretical and experimental results show that the temperature sensitivity of the fiber Bragg grating was enhanced dramatically by the structure. For example, the temperature sensitivity reached 0.08014 nm/ degrees C when the bimetallic sheets were made of aluminum and iron, which are more than eight times that of a bare fiber Bragg grating. Moreover, it was experimentally demonstrated that the structure has excellent linearity, reversibility, and stability.

Journal Article↗

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.

Journal Article↗

PubMed2006

Simultaneous measurement of stress and temperature with a fiber Bragg grating based on a loop thin-wall section beam.

We designed and demonstrated what we believe to be a novel sensor for simultaneous measurement of stress and temperature. A fiber Bragg grating is flatly adhered to the surface of a loop thin-wall section beam. The theoretical analyses and the experimental results show that both the central wavelength shift and the chirped bandwidth of the grating reflection spectrum have a linear relationship with the stress and the temperature, respectively, and the slopes of them are different. Therefore, the temperature and stress can be discriminated by interrogating the chirped fiber grating. Moreover, we also investigated the strain of the loop thin-wall section beam, and the results show that the strain is cosine proportional to the double positional angle.

Journal Article↗

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.

Journal Article↗