Research On Fabrications And Applications Of Optical Sensors Based Upon Tapered Structures

With the rapid development of Optoelectronic Technology and theemergence of1550nm low loss single-mode optical fiber, technology ofoptical fiber communication and optical fiber sensing has become themost popular research technical communication and sensing fields.And especially, optical fiber sensing technology has been Widely usedin aerospace, oil exploration and exploitation and biomedical fields.It not only has high detection sensitivity, but also can realize tolong-term work at High temperature, high humidity and highelectromagnetic radiation and other harsh environmental conditions.Relative to the Electrical sensing technology, another advantage ofoptical fiber sensing technology is that it can be used to the distributedsensor system. This distributed sensor system is an important part of theInternet of things technology.Tapered fiber has small size and simple preparation process. It hasultra high sensitivity to temperature, pressure, refractive index, and notonly was widely used in medicine, near field optical microscopy andoptical soliton communication, but also was used as efficient sensingelement. The characteristic and application of tapered fiber have gotmore and more attention. This paper dose an in-depth study in the constructure of optical fibersensor preparation, sensor characteristics and application. The workmainly in the following aspects:A compact fiber tip modal interferometer (FTMI) based ontwo-wave interference has been demonstrated.Its fabrication process is very simple, just involving fiber taperingby a fusion splicer. The effective sensing area of the FTMI has a smalllength of～310μm.The interference spectra of the fiber tips depend on the size andprofile of the fiber sensor.The FTMI has a good mechanical strength and high-temperaturestability. And different attenuation peaks have different response to theenvironment changes.It can be used for high-temperature and transverse load sensingsimultaneously in a harsh environment when two different attenuationpeaks are chosen to be monitored.An single-mode-fiber Mach–Zehnder interferometer (MZI) bycascading two “double-J” shape thinned core structures forsimultaneous measurement of temperature and surroundingrefractive index (SRI) has been achieved.The “double-J” shape thinned core structure is fabricated by fusionsplicing two sections of single-mode fibers with large lateral offset.At the same time, we analyses the work mechanism and thefeasibility in detail to sensor to double parameters. The experimentalresults and the theoretical results are accordant. The relationshipbetween these variables is expressed in the form of matrix. Zinc oxide films prepared by magnetron sputtering are introducedto the electro-optical detection to improve the voltage sensitivity. Withthe help of large piezoelectric effect, ZnO films make up for thedeficiency of the low electro-optical coeffcient.In this paper, we preparated tiper fiber electric field sensor based onZinc oxide films. We illustrated the mechanism of piezo-inducedenhancements, and measured the electric signals on the line of coplanarwaveguides.This method breaks through the limit of material species foropto-electronically responsive sensing, and shows promisingapplications in optical detection.