Dispersion measurement of a short length optical fiber using Fourier transform spectroscopy

A lot of specialty optical fibers and devices with specific dispersion characteristics are being developed to manipulate pulse broadening effects as well as nonlinear interactions in optical fiber communication systems. Measurement of chromatic dispersion is an essential part of developing a new optical device. A modulation phase shift technique a is commonly used time-of-flight method for measuring chromatic dispersion of a fiber due to its accuracy and repeatability. After transmitting a phase modulated optical signal through a long length (/spl sim/1 km) of a test fiber, it measures phase delay as a function of wavelength. Hence, it requires complicated experimental setups and expensive equipment such as high-speed optical modulators and detectors, optical tunable filters, etc. As it also requires a long length of a test fiber, it can be used neither for determining variation of dispersion along a fiber nor for measuring dispersion of short optical devices such as a fiber grating device. In this paper, we represent a simple and accurate interferometric dispersion measurement technique using Fourier transform spectroscopy. Conventional interferometric dispersion measurement methods require either an expensive tunable laser source or an optical spectrometer to obtain chromatic dispersion values at various wavelengths. However, this method just needs a broad band LED as a source and a slow detector.