Correlation of supermode noise of harmonically mode-locked lasers

Two types of supermode noise spurs, uncorrelated and correlated, are measured for two different types of harmonically mode-locked lasers utilizing a dual grating pulse shaper as a means to determine the correlation. The correlated supermode noise spur, as measured with the residual phase noise technique, is related to the excitation of multiple correlated optical supermodes in the spectral domain and has a large impact on the noise behavior of optical pulse trains after propagation through a long optical fiber.