Precise Measurement of Fiber Third-Order Dispersion Using Transfer Function of a Microwave Photonic Filter

Third-order dispersion (TOD) is a fundamental parameter to characterize optical fiber. In this paper, we propose a method to precisely measure TOD of an optical fiber by using the amplitude and phase transfer function of a microwave photonic filter (MPF). The fiber under test (FUT) plays an important role in the MPF, of which the transfer function has a quadratic phase distortion due to the TOD of the FUT. Through iteratively modifying the quadratic phase spectral coefficient of the optical signal in the MPF to counteract the TOD effect, the transfer function distortion can be almost compensated. According to the definite relationship between the TOD and the compensation coefficient, we can determine the TOD precisely. In the experiment, the measurement uncertainty of 0.2% is obtained of a dispersion compensating fiber, designed for the compensation of 80 km standard fiber.