Photonic Crystal Fiber Loop Mirror Research Articles

Design of highly-sensitive fiber thermal anemometer based on reflective photonic crystal fiber loop mirror

• A reflective fiber loop mirror is firstly used in flow rate sensing. • The proposed sensor exists an infinite temperature-sensitivity point, which can be adjusted. • The fiber thermal anemometer has high sensitivity and long-distance sensing capability. A highly-sensitive fiber thermal anemometer was proposed and numerically designed based on reflective fiber loop mirror (RFLM). One ethanol-infiltrated birefringent photonic crystal fiber (BPCF) was imbedded in the RFLM as the sensing head, whose output interference spectrum was sensitive to surrounding temperature. Laser was used to heat the BPCF to a fixed temperature, but the temperature changed with the variation of surrounding flow rate. Therefore, the flow rate could be measured by monitoring the wavelength shift of the output spectrum. Through numerical analyses on the characteristics of the RFLM, the relationship between the flow rate and the temperature of the BPCF was numerical studied and then the structure parameters of the BPCF were optimized. Finally, numerical results showed that the maximum detectable flow rate could be enlarged to 20.8 m/s with the detection limit of 0.3 m/s, when the laser power was 100 mW. In addition, the defined quality parameter Q demonstrated that the sensitivity was improved to about 20 times.

Simultaneous measurement of torsion, strain and temperature using a side-leakage photonic crystal fiber loop mirror

A fiber optic sensor for simultaneous measurement of multi-parameter is proposed. The fiber sensor is realized by a fiber loop mirror based on a piece of homemade side-leakage photonic crystal fiber. Affected by the group birefringence of the side-leakage photonic crystal fiber, which induced by the elliptical germanium-doped core and the linear side-leakage defect, the fiber loop mirror has different wavelength responses to torsion, strain and temperature at different interference fringe valleys. By monitoring the wavelength shifts of three selected valleys in the transmission spectrum, simultaneous measurement of torsion, strain and temperature is achieved. The maximal sensitivities to torsion, strain and temperature are 151.14pm/°, 1pm/με and 71pm/°C, respectively.

Torsion Sensor Based on Polarization-Maintaining Photonic Crystal Fiber Loop Mirror with an Output Port Probe

Torsion Sensor Based on Polarization-Maintaining Photonic Crystal Fiber Loop Mirror with an Output Port Probe

Simultaneous measuring of magnetic field and temperature based on photonic crystal fiber loop filled with magnetic fluid

ABSTRACTA novel simultaneous measurement method for magnetic field and temperature is proposed based on the photonic crystal fiber loop mirror selectively filled magnetic fluid. The measuring principle was introduced in detail and verified by experiment. Sensitivity coefficients that the pitch between adjacent resonant valley and the resonant valley drift changed with temperature and magnetic field were achieved theoretically and found to be consistent basically. Therefore, the temperature and magnetic field can be simultaneous detected according to the two‐parameter matrix. The measurement errors and the fitting curves between resonant valley pitch, resonant valley shift, and temperature/magnetic field were given by experiment. The results show that the theoretical calculations and experimental results are basically consistent, and the scheme is feasible. The detection resolution of temperature and magnetic field were 0.07°C and 0.41 Oe respectively for resolution of 0.02 nm spectrometer. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2548–2552, 2014

High‐sensitive temperature sensor based on an alcohol‐filled HiBi photonic crystal fiber loop mirror

ABSTRACTA temperature sensor based on a High‐Birefringence photonics crystal fiber loop mirror (HiBi‐PCF‐FLM) with a reflection probe was theoretical simulated and experimentally demonstrated. The interference spectrum of the FLM presented high sensitivity to temperature variation of the surrounding medium. High‐temperature sensitivity of 7.38 nm/°C with good linearity was obtained in theory; this result was proved by the consequent experiment. Meanwhile, the measuring range of temperature can be tuned using the HiBi‐PCF with different length or Birefringence. As the reflection probe is a reflected structure, it is benefit to use in the area of high‐sensitivity remote temperature sensing. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1334–1337, 2014

Three methods for improving an axial strain sensitivity of polarization maintaining fiber loop mirror

Sensitivity is one of the important performances for sensor. Theoretical results show that we can choose a long wavelength monitoring point, a high strain dependent birefringence coefficient polarization maintaining fiber (PMF) and a low birefringence PMF to improve the axial strain sensitivity of PMF loop mirror, and experimental results show that the axial strain sensitivity has respectively been improved by 8.06, 30.73, and 22.26% by these methods. The advantage of these methods is to improve the axial strain sensitivity without increasing system complexity. These results help to improve the temperature, displacement, torsion, curvature and liquid level sensitivities of PMF loop mirror. These results can also be applied in photonic crystal fiber loop mirror.

The influences of polarization-maintaining fiber length and sensing length on axial strain sensitivity of polarization-maintaining fiber loop mirror

It is difficult to make sure that the spliced polarization-maintaining fiber length is the same in every fabricating polarization-maintaining fiber loop mirror sensor, and it is also difficult to make sure that sensing length is the same in every experiment. To find out how these uncertain factors influence the axial strain sensitivity of polarization-maintaining fiber loop mirror, we perform the research on the influences of polarization-maintaining fiber length and sensing length on axial strain sensitivity. In this article, a theoretical model for axial strain sensitivity of polarization-maintaining fiber loop mirror is deduced first. By analyzing the theoretical model, we find that the axial strain sensitivity is unrelated to polarization-maintaining fiber length and sensing length. Then, we experimentally investigate the influences of polarization-maintaining fiber length and sensing length on axial strain sensitivity of polarization-maintaining fiber loop mirror. The axial strain sensitivities in the experiments are almost the same for different polarization-maintaining fiber lengths and different sensing lengths. The experimental results agree with the theoretical ones. The results can provide help for fabricating and applying polarization-maintaining fiber loop mirror sensor. The results can be applied in the temperature, displacement, and vibration sensors of polarization-maintaining fiber loop mirror and can also be applied in photonic crystal fiber loop mirror sensor.

High-sensitivity temperature sensor based on an alcohol-filled photonic crystal fiber loop mirror

A compact temperature sensor based on a fiber loop mirror (FLM) combined with an alcohol-filled high-birefringence photonic crystal fiber (PCF) is proposed and experimentally demonstrated. The output of the FLM is an interference spectrum with many resonant dips, of which the wavelengths are quite sensitive to the change of the refractive index of the filled alcohol for the interference of the FLM. Simulation analysis predicts a high temperature sensitivity, and experimental results show it reaches up to 6.6 nm/°C for the 6.1-cm-long PCF used in the FLM.

Intensity measurement based temperature-independent strain sensor using a highly birefringent photonic crystal fiber loop mirror

A fiber-optic strain sensor is demonstrated by using a short length of highly birefringent photonic crystal fiber (HiBi-PCF) as the sensing element inserted in a fiber loop mirror (FLM). Due to the ultralow thermal sensitivity of the HiBi-PCF, the proposed strain sensor is inherently insensitive to temperature. When a distributed-feedback (DFB) laser passes through the FLM, the output power is only affected by the transmission spectral change of the FLM caused by the strain applied on the HiBi-PCF. Based on intensity measurement, an optical power meter is adequate to deduce the strain information and an expensive optical spectrum analyzer (OSA) would not be needed.

Multiwavelength fiber laser based on a photonic crystal fiber loop mirror with cooperative Rayleigh scattering

In this work, a multiwavelength fiber Raman laser based on a highly birefringent photonic crystal fiber loop mirror is presented. A laser resonator is formed when the Raman amplification with cooperative Rayleigh scattering in a dispersion-compensating fiber is used as a distributed mirror and combined with a photonic crystal fiber loop mirror filtering structure. Stable multiwavelength lasing at room temperature is achieved due to the low temperature sensitivity of the highly birefringent photonic crystal fiber.

Switchable dual-wavelength erbium-doped fiber laser based on the photonic crystal fiber loop mirror and chirped fiber Bragg grating

The switchable dual-wavelength erbium-doped fiber laser (EDFL) with a two-mode photonic crystal fiber (PCF) loop mirror and a chirped fiber Bragg grating (CFBG) at room temperature is proposed and experimentally demonstrated. The two-mode PCF loop mirror is formed by inserting a piece of two-mode PCF into a Sagnac loop mirror, with the air-holes of the PCF intentionally collapsing at the splices. By adjusting the state of the polarization controller (PC) appropriately, the laser can be switched between the stable single- and dual-wavelength operations by means of the polarization hole burning (PHB) and spectral hole burning (SHB) effects.

Temperature-Independent Strain Sensor Based on a Hi-Bi Photonic Crystal Fiber Loop Mirror

This work presents an optical sensor based on a highly birefringent photonic crystal fiber (Hi-Bi PCF) loop mirror. The length of the sensing head is 380 mm and its corresponding wavelength spacing between two interferometer minima is 8 nm. The optical sensor was characterized in strain and in temperature with an uncoated Hi-Bi PCF and with an acrylate coated Hi-Bi PCF. Different results for strain and temperature sensitivity were obtained. Relatively to the strain measurement, the sensor with the uncoated Hi-Bi PCF presents slightly less sensitivity (1.11 ) when compared with coated Hi-Bi PCF (1.21 ). For the temperature measurement and with the uncoated Hi-Bi PCF, the optical sensor is insensitive to temperature (0.29 pm/K).