Optically Differential Phase Detection Using Cross-Talk Mode of Series Fabry-Perot Sensors in PMDI

摘要

The signals between cascaded Fabry-Perot sensors have serious cross-talk problems due to complex phase interactions between sensors. However, cross-talk mode in cascaded Fabry-Perot sensors can be employed for demodulating optically differential-phase in a path-matching differential interferometry (PMDI). This paper presents a novel design in two series Fabry-Perot sensors for a differential-phase measurement analyzed by an optical spectrum analysis. The spectrum transfer function in a light source and Fabry-Perot cavities are simulated by a Gaussian distribution spectrum and a low-finesse reflectivity, respectively. It shows that two series Fabry-Perot sensors with the differential-phase measurement can be designed accurately. Experimental data shows that the novel design in measuring a differential-phase between two series Fabry-Perot sensors is achieved. This design in two series Fabry-Perot sensors for a differential-phase measurement can be applied to unbalanced system detection or noise compensations.