Study On Stability And Working Point Of Fiber-optic Interferometer

As a new kind of detection technology, optical fiber sensor has been paid more and more attention. Compared with other optical detecting methods, optical fiber sensors based on fiber-optic interferometer possess higher sensitivity and accuracy and are rapidly being developed and applied in lots of fields. The random phase drift due to environmental changes often causes the work point of fiber-optic interferometer departing from the center of linear region and seriously affects the working status of the interferometer so serious that. the fiber interferometer could not work well. The instability of work point in the fiber interferometer has become a key issue in the research of optical fiber sensor.There are two fiber arms in most of the traditional fiber interferometers. to produce the interferential signal. The external events act on a fiber arm and generate the phase modulation. The light from the arm meet the light from other arm, and the interference happens. The external events can be demodulated from the interference signal. This kind of method possesses high sensitivity. But the environmental random changes may cause different effects on the two fiber arms, so many other external random disturbances will cause a random drift of the work point and damage the stability of the fiber interference.Firstly, a research is carried on the Michelson fiber interferometer. A control and servo system for the Michelson fiber interferometer has been developed to compensate phase random drift to stabilize the working state of the interferometer and a stability has been achieved for a moment. To get a more stable interferometer structure, a series of new structures have been analyzed. Finally a kind of stabile fiber interferometer has been developed based on Fizeau interferometer and a continuous detecting experiment has been realized for the case of continuous vibrating generated by a continuous signal in the sine form. Experimental results show that this kind of fiber interferometer could detect the vibration signal accurately and steadily and is more stable than Michelson fiber interferometer.In addition, a method based on the deformations of the waveform has firstly been proposed to estimate and adjust the work point of fiber interferometer quickly. And the idea has been safeguarded by the application of national invention patent accredit. This method is used to estimate and adjust the work point of the Fizeau fiber interferometer and the accuracy of adjustment can reach sub-micron level.