The influences of polarization-maintaining fiber length and sensing length on axial strain sensitivity of polarization-maintaining fiber loop mirror

It is difficult to make sure that the spliced polarization-maintaining fiber length is the same in every fabricating polarization-maintaining fiber loop mirror sensor, and it is also difficult to make sure that sensing length is the same in every experiment. To find out how these uncertain factors influence the axial strain sensitivity of polarization-maintaining fiber loop mirror, we perform the research on the influences of polarization-maintaining fiber length and sensing length on axial strain sensitivity. In this article, a theoretical model for axial strain sensitivity of polarization-maintaining fiber loop mirror is deduced first. By analyzing the theoretical model, we find that the axial strain sensitivity is unrelated to polarization-maintaining fiber length and sensing length. Then, we experimentally investigate the influences of polarization-maintaining fiber length and sensing length on axial strain sensitivity of polarization-maintaining fiber loop mirror. The axial strain sensitivities in the experiments are almost the same for different polarization-maintaining fiber lengths and different sensing lengths. The experimental results agree with the theoretical ones. The results can provide help for fabricating and applying polarization-maintaining fiber loop mirror sensor. The results can be applied in the temperature, displacement, and vibration sensors of polarization-maintaining fiber loop mirror and can also be applied in photonic crystal fiber loop mirror sensor.