METHOD AND CIRCUIT FOR DETECTING FREQUENCY SWEEP ERROR, OPTICAL FREQUENCY SWEEP LIGHT SOURCE, AND OPTICAL FREQUENCY AREA REFLECTION MEASURING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To detect a precise frequency sweep error and perform an optical frequency sweep with high linearity by inputting an output light to a two-optical path interference system, giving a prescribed frequency shift to the light passing one optical path, and selecting either the bead signals of the upper band waves or the bead signals of the lower band waves. SOLUTION: A frequency shift is imparted to the light passing one optical path of a two-optical path interference system 56', and only the bead signals of the primary modulated side band waves are separated on the frequency axis and selected by a band pass filter. Thus, frequency fluctuation can be precisely measured in a frequency fluctuation measuring means 58, and the frequency sweep error of an optical frequency sweep light source 51 can be precisely detected. The frequency sweep error is fed back to the optical frequency sweep light source 51, whereby the optical frequency sweep with good linearity can be performed.