Measurements of wavelength dispersion based on Fourier-transformed OTDR: from laser cavities down to semiconductor waveguides

Wavelength dispersion measurement method has been drawing much attention as an indispensable tool for the ultrafast optics research and development. Recently a new type of measurement, that is, measurements for a whole laser cavity, has been pursued, and by using a method called frequency domain dispersion (FDD), S.W. Knox first measured the dispersion in a live modelocked laser. For this purpose, on the other hand, we proposed the cavity Fourier-transformed crosscorrelation (FTC) method which is an extention of the interferometric method. Later, with an introduction of dual interferometer, i.e. a scheme to nullify the influence of sample length fluctuations, this cavity FTC method found very broad application areas from a solid-state femtosecond laser cavities down to semiconductor passive waveguides