Research And Characterization Of Complex Devices Fiber Interferometer

Fiberopticsensorwithhighsensitivity,anti-electromagneticinterference,high-temperature resistance,corrosion resistance,light weight,and bandwidth get more development and application.The trend of fiber optic devices has been changed from single function to complex functions,from simple structure to complex structures,from single core fiber to multi-core fiber.In this thesis,several kinds of fiber optic devices and a sort of self-accelerating beam generation fiber apparatus are proposed based on the development status of fiber optic devices.Firstly,a Michelson-FP composite fiber interferometer based on dual-core optical fiber is proposed.Integrated dual-core fiber Michelson interferometer,optical fiber tube and single-mode fiber were spliced together in due order to realize the recombination between Michelson interference and FP interference.By using FFT,we extract the desired high and low frequency signals from fiber interferometer spectrometer collected spectra and process the low frequency and high frequency interference experiment data through spatial filtering and FFT inverse transform.This composite interferometer realizes simultaneous measurement of strain and bending,and the sensitivity is 15.2pm/??and 1.333nm/m^-1respectively.Through the refractive index sensing property of a kind of SMF Michelson interferometer based on single-mode-multimode-single-mode,the relationship between the different modal interferences and the refractive index insensitivity is discussed in this thesis.Then,analyze the reasons of blue shift and red shift in the refractive index sensitivity measurement experiment.By analysising the experiments of the SMS structure Michelson interferometer with different lengths of MMF,the signs of the RI sensitivity will be verified.RI sensitivity is negative when the interference appears between the core mode and lower order cladding modes,whereas RI sensitivity is positive when the interference appears between the core mode and higher order cladding modes,or between two different cladding modes.A compact fiber Mach–Zehnder interferometer?MZI?is proposed which is based on a hollow annular core fiber?HACF?.The MZI is fabricated by splicing a short section of HACF between two short pieces of multimode fibers,and interference occurs between the light beams transmitting along the air hole and annular core of the HACF.Curvature and temperature can be measured through fringe contrast variation and wavelength shift of the interference spectrum,respectively.The unique characteristics of the proposed device are:the wavelength of the transmission spectrum interference dip is sensitive to temperature but insensitive to curvature;the transmission spectrum fringe contrast is sensitive to curvature but insensitive to temperature;both the wavelength and the spectrum fringe contrast are insensitive to external RI.The experiment results show that the temperature sensitivity is 30pm/oC in the range of 30oC-100oC,and the maximum contrast variation is 32.4 dB in the curvature range of 0.555 m^-1-5.405 m^-1.The thesis demonstrates a semi-open cavity in-fiber M–Z interferometer sensor based on optical fiber tube?OFT?for temperature measurement with ultra-high sensitivity.The interferometer is composed of an OFT sandwiched between two multimode fibers,with lateral offset.Pour ethanol or distilled water into the unsealed OFT air hole.The light traveling through the silica tube will interfere with the light traveling through the liquid-filled cavity,and this is the M–Z interference.When poured ethanol into the unsealed OFT air hole,the sensor temperature sensitivity is up to 7.17 nm/oC due to high thermo-optical coefficient of ethanol,this sensor have increased the temperature sensitivity by two orders of magnitude compared to other kinds of temperature measurement sensor based on optical grating or modal interference.The thesis has also proposed and demonstrated one sort of all-fiber device which can generate self-accelerating Bessel-like beam and verified the lateral self-accelerating property of the beam by studying the results of the simulation and experiment.Then demonstrated its'application in optical trapping and transport.In this device,the Bessel-like beam is excited through splicing a piece of SMF with a piece of MMF.Then make the other end of the MMF into a sphere len by arc discharge.Finally this sphere len will cause the lateral self-accelerating phenomenon of the Bessel-like beam.