Weiqian Duan

An embedded pressure sensor based on polarization maintaining photonic crystal fiber

An embedded optical fiber pressure sensor was made by sandwiching a piece of polarization maintaining photonic crystal fiber (PM-PCF) between two polymer foils. The excess birefringence induced by the transverse pressure applied in different directions with respect to the birefringent axes of the PM-PCF was numerically calculated and the slow axis was identified to be the most sensitive direction. An experimental test was carried out by incorporating the embedded PM-PCF sensor in a Sagnac interferometer; the output interference fringes were found to shift linearly with the applied transverse pressure with a peak wavelength to pressure sensitivity of 1.764 nm MPa–1, which corresponds to a birefringence to pressure sensitivity of 2.476 × 10−6 MPa−1.

Polarization maintaining photonic crystal fiber IFOG

Polarization maintaining (PM) photonic crystal fiber (PCF) and Er-doped PCF technologies are investigated for interferometer fiber optic gyroscope (IFOG) applications. A PM-PCF optimized to achieve low-loss and high polarization extinction splice-joints with conventional PM fiber pigtails of a multifunction integrated optical circuit (MIOC) was drawn and tested under different temperature conditions. The loss and polarization crosstalk properties of a fiber coil made from the PM PCF were measured and compared with conventional PM fiber. An erbium-doped PCF was designed and fabricated, with which a superfluorescent fiber source (SFS) was made and tested. The results show that an IFOG with the PM-PCF coil and the Er-doped PCF source could achieve better temperature performance. An experimental PCF-based prototype IFOG was built and tested , and preliminary results was obtained.

Experimental investigation of birefringence of solid core polarization maintaining photonic crystal fibers

We characterized the temperature sensitivity of birefringence of typical solid core polarization maintaining photonic crystal fiber (PM-PCF). Mainly the temperature dependence of birefringence is determined by two factors which are thermo-optic effects and thermal expansion. Numerical simulation with ANSYS and RSOFT show that the birefringence temperature susceptibility can be described as a polynomial function of Λ (distance between small holes) and zero temperature coefficient may be obtained at optimum Λ. A high precision birefringence measure setup was built and the birefringence of five PM-PCFs samples with different Λ were measured under different temperature. The experimental result agreed well with the simulation.

Measure and redress of mode field diameter of polarization maintaining photonic crystal fibers

The measurement technology of mode field diameter (MFD) of polarization maintaining photonic crystal fiber (PM PCF) was demonstrated and experimentally investigated based on near field spot image. The PM PCFs MFD evolution under arc discharge was investigated and it was found that the MFD can be redressed effectively with this method. Experimental studies proved that the low loss splicing can be achieved after redressing the MFD of PM PCFs appropriately by controlling the arc discharge current.

Embedded pressure sensor based on birefringent photonic crystal fiber

An embedded pressure sensor was made by sandwiching a polarization maintaining photonic crystal fiber (PM-PCF) between two polymer foils. The excess birefringence induced by transverse pressure applied along the slow-axis of a PM-PCF was numerically simulated with a finite element method. Experiment was carried out with a Sagnac interferometer with the embedded PM-PCF as part of the Sagnac loop. The output interference fringes were found shift linearly with applied transverse pressure with a wavelength to pressure sensitivity of 1.764 nm/MPa, The measurement precision of 0.2%, and a dynamic range of 2.5 MPa were achieved.

High precision measurement technology for beat length of birefringence optical fiber

Based on hybrid Sagnac interferometer formed with single directional coupler and polarization maintaining fiber (PMF) under test, a high precision measurement technology for beat length of birefringence fiber is proposed. The measure error is analyzed and the optimum measure condition is defined. With the high performance optical sensing interrogator technology, the beat length measure precision can be better than 0.001 mm. The verify test is made experimentally. The beat length stability of PMF and polarization maintaining photonic crystal fiber (PM PCF) has been measured and compared too. The result proves the excellent birefringence temperature stability of PM PCF.