Polarization Dependent Fiber Mach-Zehnder Interference Device And Its Applications

Owing to the advantages of high sensitivity, flexible, diverse structuresand extensive measurement objects, optical fiber interferometer-based sensors havebeen widely used in many sensor fields. In this paper, a series of novel polarizationdependent fiber Mach-Zehnder interferometer (MZI) devices were designed. Andtheir applications in sensing field were verified by experimental. The main contentsare shown as following:1. The development of the novel in-fiber MZI was introduced. They areclassified in types according to their fabrication methods. The advantages anddisadvantages of each type were briefly commented. The mechanism of in-fiber MZIwas studied based on the modes interference theory.2. A polarization dependent in-fiber MZI was proposed. The high order claddingmodes of polarization maintain fiber was excited through a core-offset fusionsplicing method. A polarization dependent MZI was formed through the interferencebetween the fast and slow axis polarization modes corresponding the fiber core andcladding The fabrication process of the interferometer was optimized, and thesensing characteristic of the interferometer was discussed.3. A polarization-dependent two-dimensional micrometric displacement sensorbased on an in-fiber MZI was proposed. The interferometer was fabricated byinserting a polarization maintaining fiber (PMF) between two conventionalsingle mode fibers (SMFs). One SMF was mismatch fusion spliced along45odirection between the fast axis and slow axis of the PMF. The other SMF wasmismatching connected to the PMF without fusion splicing. Thetwo-dimensional micrometric displacement along PMF on the slow axis andfast axis directions can be detected. Experimental results showed that theproposed sensor has the sensitivities of-0.301dB/μm and-0.669dB/μm on thefast axis and slow axis directions. On this basis, a novel fused tapertechnology was proposed. Combining with the core-offset fusion splicing method, a MZI based micrometric displacement sensor with high sensitivityof-1.89dB/μm was obtained.4. A polarization-dependent curvature sensor based on an in-fiber MZI withdifference arithmetic demodulation method was proposed. Two SMFs weremismatch fusion spliced along45odirection between the fast axis and slowaxis of a PMF to form the MZI. Experimental results showed that theproposed sensor has high sensitivity of-0.882dB/m-1under the measurementrange of0to0.35m-1. Benefited from the using of difference arithmeticdemodulation method, the temperature-curvature cross-sensitivity and lightsource power perturbation effects on the proposed sensor are decreased by94%and91%, respectively.