Microfiber Optical Sensors: A Review

Abstract

With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, fast response, high flexibility and low optical power consumption. Here we review recent progress in microfiber optical sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber optical sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber optical sensors.

Nanomaterials for early detection of cancer biomarker with special emphasis on gold nanoparticles in immunoassays/sensors

“…Use of optic fibers in sensors are now being replaced by optical microfibers due to their special advantages being tight optical confinement, large fractional evanescent fields, outstanding mechanical flexibilities and fast response (Lou et al, 2014). Microfibers are fabricated by taper drawing of glass/polymer optic fibers and hence they provide miniaturized platform for optical sensing with high sensitivity and low power consumption (Fig.…”

Microfiber as light source for exciting fluorescence in a polymer optical fiber

“…Thus, in the field of sensing we find MNFs in varied configurations, such as biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, among other structures combining them, which are applied to physical and bio/chemical sensing [3].…”

Variable Waist-Diameter Mach–Zehnder Tapered-Fiber Interferometer as Humidity and Temperature Sensor

“…Moreover, the small dimensions of the optical fiber sensors make them suitable to packaging into lightweight devices or embedded in polymer materials ergonomically. Last but not least, the sensitivity of optical fiber sensors are normally higher than the conventional sensors once they operate at high resolution [3], [4]. The guided light in the fiber core and the surrounding medium (evanescent field effect for tapered fiber) collected in fiber optic humidity sensors (FOHS).…”