Peng Zu

Magneto-optical fiber sensor based on magnetic fluid

A novel tilted fiber Bragg grating (TFBG)-based magnetic field sensor by incorporating magnetic fluid is proposed and experimentally demonstrated. It is based on the refractive index change of magnetic fluid with external magnetic field. Magnetic field strength measurement is successfully achieved within a range from 0 to 196 Gauss by monitoring extinction ratio of the TFBGs cladding mode resonance, which is sensitive to surrounding refractive index.

Magneto-optical fiber sensor based on bandgap effect of photonic crystal fiber infiltrated with magnetic fluid

A magnetic field sensor based on combination of the magnetic fluid and the tunable photonic bandgap effect of photonic crystal fiber is proposed. The magnetic fluid with higher refractive index (>1.45) is prepared and filled into the air-holes of photonic crystal fiber to convert the index guiding fiber into photonic bandgap fiber. The proposed sensor takes full advantage of the ultrahigh sensitivity characteristic of photonic bandgap fiber and achieves a high sensitivity and resolution of 1.56 nm/Oe and 0.0064 Oe, respectively, which are 2-3 orders of magnitude better than other sensors based on magnetic fluid.

Temperature-Insensitive Magnetic Field Sensor Based on Nanoparticle Magnetic Fluid and Photonic Crystal Fiber

A novel magnetic field sensor based on the magnetic fluid and Mach-Zehnder interferometer is proposed. The sensor takes advantage of the tunable refractive index property of the magnetic fluid and the modal interference property of the collapsed photonic crystal fiber. The achieved sensitivity and resolution of the sensor are 2.367 pm/Oe and 4.22 Oe, respectively. The magnetic field sensor is insensitive to the temperature variation with a temperature coefficient of 3.2 pm/°C.

A Temperature-Insensitive Twist Sensor by Using Low-Birefringence Photonic-Crystal-Fiber-Based Sagnac Interferometer

An optical fiber twist sensor is proposed by using solid core low birefringence photonic crystal fiber (LB-PCF)-based Sagnac interferometer. The twist effects on the fiber are theoretically analyzed. The results show that the dip wavelength of the transmission spectrum shifts with the twist angle with a high sensitivity and resolution of 1.00 nm/0 and 0.010 , respectively. The sensor is also insensitive to environmental temperature change with an ultralow thermal dependent coeffiecient of -0.5 pm/0C.

Magnetic field sensor using tilted fiber grating interacting with magnetic fluid.

A novel magnetic field sensor using tilted fiber Bragg grating (TFBG) interacting with magnetic fluid is proposed and experimentally demonstrated. The TFBG is surrounded by magnetic fluid whose complex refractive index changes with external magnetic field. The guiding properties of cladding modes excited by the TFBG are therefore modulated by the external magnetic field. As a result, the magnetic field strength measurement is successfully achieved within a range up to 196 Gauss by monitoring extinction ratio of cladding mode resonance. Furthermore, temperature variation can be obtained simultaneously from the wavelength shift of the TFBG transmission spectrum.

Magneto-optic fiber Sagnac modulator based on magnetic fluids

A magneto-optic modulator with a magnetic fluid film inserted into an optical fiber Sagnac interferometer is proposed. The magnetic fluid exhibits variable birefringence and Faraday effect under external magnetic field that will lead to a phase difference and polarization state rotation in the Sagnac interferometer. As a result, the intensity of the output light is modulated under the external magnetic field. Moreover, the modulator has a high extinction ratio and can easily be integrated in a single-mode fiber system. The performance of the modulator is not affected by ambient temperature variation from room temperature to 40 °C.

Humidity Sensor Based on a Multimode-Fiber Taper Coated With Polyvinyl Alcohol Interacting With a Fiber Bragg Grating

An optical fiber relative humidity (RH) sensor is proposed and experimentally demonstrated with a multimode-fiber taper coated with a layer of polyvinyl alcohol cascading with a fiber Bragg grating. The operation is based on the interaction between the optical evanescent field and the coating along the taper waist. Humidity changes the refractive index of the extended coating, thus transmission loss of the light signal is introduced and humidity measurement is therefore realized. The measurement sensitivity is enhanced since the light passes through the taper twice. A maximum sensitivity of 1.994 μW/%RH is achieved within the measurement range of 30-95%RH with the taper waist diameter of 50.2 μm. The average response time is ~2 s and the measurement is nearly insensitive to temperature.

Photonic Crystal Fiber Strain Sensor Based on Modified Mach–Zehnder Interferometer

In this paper, a novel strain sensor is proposed and demonstrated by employing a modified photonic crystal fiber (PCF)-based Mach-Zehnder interferometer, in which a collapsed region is introduced at the middle point of the PCF to improve the extinction ratio. Experimental results show that this proposed structure has a high sensitivity of 11.22 over a range of 1.28 and high-temperature stability.

Intensity-modulated magnetic field sensor based on magnetic fluid and optical fiber gratings

An intensity-modulated magnetic field sensor based on magnetic fluid and optical fiber gratings is proposed and experimentally demonstrated. The sensor is formed by a tilted-fiber Bragg grating (TFBG) coated by magnetic fluid (MF) and cascaded by a chirped-fiber Bragg grating (CFBG). Transmission of the TFBG is modulated by refractive index of the MF, which is sensitive to external magnetic field. The CFBG is well designed to reflect a broadband of light spectrally located at the cladding mode resonances region of the TFBG. Therefore, reflected optical power is modulated twice by the magnetic field and measurement is realized in reflection manner.

Temperature Sensing Based on Ethanol-Filled Photonic Crystal Fiber Modal Interferometer

A modal interferometer made of a short ethanol-filled photonic crystal fiber (PCF) combined with a fully collapsed splicing with single-mode fibers (SMFs) is proposed for temperature measurement. Two fully collapsed splicing regions between the ethanol-filled PCF and SMFs excite and recombine two interfering modes in the ethanol-filled PCF. The interference spectrum of the ethanol-filled PCF is more sensitive to temperature than that of original PCF. By monitoring one peak wavelength shift of the ethanol-filled PCF modal interference spectrum, the temperature sensitivity reaches up to -0.35 nm/°C for a 3.25-cm long ethanol-filled PCF.