On using fiber transfer functions to characterize laser chirp and fiber dispersion

Two measurement techniques for estimating the /spl alpha/ parameter of a laser, the frequency f/sub c/ for which the adiabatic and transient chirp of a laser have the same magnitude, and the dispersion coefficient D of an optical fiber are compared. The techniques rely on either a single measurement of the transfer function of a dispersive optical fiber using direct modulation of the laser, or two measurements of the fiber transfer function using external and direct modulation of the laser. Compared to the two measurement technique, the single measurement technique yields a smaller estimate of /spl alpha/ and a nearly identical estimate of f/sub c/, and can produce an unreliable estimate of D unless the frequency span in the parameter extraction procedure is sufficiently large.<>