- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Polarization-Independent Wavelength-Tunable First-Order Fiber Comb Filter
摘要： Here, we propose a polarization-independent wavelength-tunable first-order fiber comb filter based on a polarization-diversified loop configuration. The proposed filter is composed of a polarization beam splitter, two equal-length high birefringence fiber (HBF) segments, three half-wave retarders (HWRs), and two quarter-wave retarders (QWRs). Among these five wave retarders (WRs), a group of an HWR and a QWR is located in front of each HBF. The third remaining HWR is positioned after the second HBF segment and utilized to adjust the effective orientation angle of this HBF. On the basis of the filter transmittance derived through Jones formulation, orientation angle sets of the five WRs, which can induce an arbitrary phase shift from 0 to 2π in the transmittance function, are found at both flat-top and narrow band transmission spectra. From theoretical transmission spectra obtained at eight selected orientation angle sets of the five WRs, which cause phase shifts increasing linearly from 0 to 7π/4 by a step of π/4, it is confirmed that the flat-top or narrow band comb spectrum can be continuously tuned by properly controlling the WR orientation angles. Then, this theoretical prediction is verified by experimental demonstration. In particular, the spectral evolution of the output states of polarization (SOPs) of the third HWR, the last one of optical components contained within the polarization-diversified loop, is investigated on the Poincare sphere. The relationship of the passband shape and wavelength tuning with the spectral evolution of the SOP is also discussed.
关键词： optical fiber filters,high birefringence fiber,Polarization,optical fiber communication
更新于2025-09-23 15:22:29
-
A new type of structure of optical fiber pressure sensor based on polarization modulation
摘要： In this study, a new type of structure of optical fiber pressure sensor (OFPS) based on polarization modulation is proposed, which selects a high-birefringence fiber (HBF) as the sensing unit to measure the pressure in the fluid medium. The PM-1550-01 fiber produced by NTK Photonics Inc. is evaluated as the sample in our subject. Firstly, the regularities of birefringence variation on the PM-1550-01 followed by the external pressure load and the ambient temperature are analyzed by the finite element method (FEM). The results show that the pressure sensitivity is 2.05 × 10 ? 6 RIU/MPa in the pressure range of 0–100 MPa, and the temperature sensitivity is 7.27 × 10 ? 10 RIU/°C in the temperature range of 0–100 °C. Thus, the pressure-temperature cross-sensitivity is only 0.355 kPa/°C in theory. Secondly, the expression of the output light intensity of the introduced OFPS is deduced based on the principles of polarization interference and phase modulation. Combined with simulation results, the measurement ranges of the sensor can be set and adjusted by the length of the sensing unit. Finally, the proposed OFPS is fabricated and external pressure tests within the range of 0–50 MPa are completed. The results show that the pressure sensitivity is approximately 0.145 dB/MPa in the pressure range of 0–44 MPa. There is a fine consistency between the experimental data and simulation results. In addition, the proposed OFPS has many other advantages, such as small size, simple fabrication process and large measurement range, which make it appropriate to be applied in high-pressure measurement in hostile conditions, e.g., downhole and ocean-bottom.
关键词： Low temperature cross-sensitivity,Polarization modulation,High-birefringence fiber,Optical fiber pressure sensor
更新于2025-09-23 15:21:01