Research Of Low Coherence Measurement Technology And Optical Filter Characterizing

As a basic measurement method, low coherence measurement is valuable in optical device measurement, biomedical measurement and sensing area.This thesis mainly studied the key problems in the low coherence measurement system based on the Mach-Zehnder structure, which are related to establishment of system, the analysis of measuring results and application of the measure system. In the establishment of the measurement system, due to the large insertion loss of the optical system, we use lock-in amplifier which is widely used in weak signal detection to make the system more noise tolerant. In the analysis of results, we proposed a new method named reshaping-windowing method to deal with the situation that the length differences of AWG’s arrayed waveguides are close to the coherence length of the SLED light source, which improves the accuracy of the resulting determination to0.5nm. At the same time, this method also relaxes the restrictions of the system for the low coherence light source. Based on the theory we have proposed and the measurement system we have established, repeated measurements have been taken to the AWG device. We also analyzed the connection between signal noise ratio to the measurement error through simulation in Matlab. Based on the compare of repeated measurements and simulation results, we can conclude that the noise in our measurement system is different from white noise. At the same time, we analyzed other reasons contribute to the measurement errors, pointed out the shortcomings of the system and proposed the improvement advices.