Study On The Performance Measurement Of Optical Passive Components With Ultra-fine Structure

The ultra-fine characterization of the passive optical components, including amplitude,phase responses and polarization sensitivity, is very important for the measurement used inoptical communication, optical sensing, bio-engineering and so on. As optical communicationsystems rapidly towards to all-optical networks, the characterization measurement of opticalpassive components has been become a hot spot of concern to the industry. Generally, there aresome typical methods, such as an optical spectrum analyzer (OSA), optical frequency domainreflectometry and a laser scanning technique, can be used to measure the optical spectralcharacteristics of passive optical components. However, these methods are either with lowmeasurement resolution, or unable to obtain the phase responses and/or polarization sensitivity,and even with low speed of measurement, all of which make them not capable of characterizingthe ultra-fine structures of passive optical components. The method that defined optical channelestimation (OCE) using optical orthogonal frequency division multiplexed (OOFDM) signals toobtain the transfer functions of the optical channels by comparing the transmission and receptionof the OFDM signals, and then fully to characterize the device under test by the obtainedamplitude response and phase response. Because of the optical frequency combs (OFCs) withtunable frequency spacing and fixed relationship between sub-carriers, the adjacent sub-carriersare equally spaced adjacent OFDM signal, and the relationship is formed orthogonal to eachother, not only greatly extend the measurement range, and improved measurement accuracy.Based on this proposed method, we demonstrate an experiment to characterize a FBG-basedactive FP cavity etched in PM–EDF (Polarization-maintaining erbium-doped fiber) with6mmhigh-and low-reflection gratings by using the OFCs and OCE techniques. Results show that themeasurement range larger than375GHz with19.5MHz frequency resolution can be realized byusing the OFCs. Compared to traditional measurement methods, such as optical spectrumanalyzer (OSA), laser scanning technique and optical frequency domain reflectometrytechnology, our method can realize the ultra-fine characterization measurement with fastmeasurement speed, high-resolution, large measurement range and high accuracy.