Magnetic field sensor based on cascaded microfiber coupler with magnetic fluid

Abstract

A kind of magnetic field sensor based on cascaded microfiber coupler with magnetic fluid is proposed and experimentally demonstrated. The magnetic fluid is utilized as the cladding of the fused regions of the cascaded microfiber coupler. As the interference valley wavelength of the sensing structure is sensitive to the ambient variation, considering the magnetic-field-dependent refractive index of magnetic fluid, the proposed structure is employed for magnetic field sensing. The effective coupling length for each coupling region of the as-fabricated cascaded microfiber coupler is 6031 μm. The achieved sensitivity is 125 pm/Oe, which is about three times larger than that of the previously similar structure based on the single microfiber coupler. Experimental results indicate that the sensing sensitivity can be easily improved by increasing the effective coupling length or cascading more microfiber couplers. The proposed magnetic field sensor is attractive due to its low cost, immunity to electromagnetic interference, as well as high sensitivity, which also has the potentials in other tunable all-fiber photonic devices, such as filter.

High Sensitivity Refractive Index Sensor Based on Highly Overcoupled Tapered Fiber-Optic Couplers

“…This effect was proposed and demonstrated in early works to develop fiber based refractometers [14], [15]. In recent years, optical sensors based on microfiber directional couplers have been proposed and demonstrated to perform high sensitivity measurements in many practical applications [16][17][18][19][20][21][22][23]. For the specific case of fiber coupler based RI sensors, these include fused biconical fibers [24]- [26], microfibers [16], [18], [27]- [30], photonic crystal fibers (PCF) [31]- [33], and specially designed two-core optical fibers [34], [35].…”

Designing magnetic field sensor based on tapered photonic crystal fibre assisted by a ferrofluid

“…Accurate measurements of the magnetic field are of scientific and industrial importance for many applications such as medicine, military, vehicle monitoring, and geological prospecting. In the last few decades, various types of magnetic field sensor are proposed and realized, for example, based on side-polished fibre 17 , cascaded microfibre coupler 18 , fibre ring cavity laser 19 , tapered microfibre 20 , and birefringence in liquid-core optical waveguide 21 . Recently, the plasma resonance effect is used in a twin-core PCF to realise the simultaneous measurement of magnetic field and temperature 22 .…”

A Highly-Sensitive Temperature-Sensor Based on a Microfiber Knot-Resonator Packaged in Polydimethylsiloxane

“…Essentially made of micro/nano-fiber, miniature fiber-sensors, with their fast response, low transmission-loss, and compact dimensions, currently dominate the sensing field [4,5]. They are widely used to measure gas, humidity, temperature, stress, magnetic fields, refractive indexes, and other parameters [6][7][8]. Among the various device types, microfiber resonators, especially microfiber knot resonators (MKRs) [9], are promising candidates with the potential to monitor slight temperature fluctuations [10].…”