Wavelength-dependent measurements of optical-fiber transit time, material dispersion, and attenuation

A new, to our knowledge, method for measuring the wavelength dependence of the transit time, material dispersion, and attenuation of an optical fiber is described. We inject light from a 4-ns rise-time pulsed broadband flash lamp into fibers of various lengths and record the transmitted signals with a time-resolved spectrograph. Segments of data spanning a range of approxi mately 3000 Angstrom are recorded from a single flash-lamp pulse. Compariso n of data acquired with short and long fibers enables the determination of the transit time and the material dispersion as functions of wavelength dep endence for the entire recorded spectrum simultaneously. The wavelength-dep endent attenuation is also determined from the signal intensities. The meth od is demonstrated with experiments using a step-index 200-mum- diameter Si O2 fiber. The results agree with the transit time determined from the bulk glass refractive index to within +/-0.035% for the visible (4000-7200-Angst rom) spectrum and 0.12% for the UV (2650-40005-Angstrom) spectrum and with the attenuation specified by the fiber manufacturer to within +/-10%. (C) 2 001 Optical Society of America OCIS codes: 060.2300, 060.2310.