EXPANSION OF SPAN-WIDTH OF AN OPTICAL FREQUENCY COMB USING A HIGHER HARMONIC WAVE MODULATION

We propose a novel method for expanding the span-width of an optical f requency comb that utilizes modulation by a superposition of higher ha rmonic waves, Based on the calculations, it was found that in the term s up to third-order harmonic wave, the optimum superposition is the on e whose power ratio between the fundamental and the third-order harmon ic waves is 1:1. The validity of this method was experimentally confir med at 1.5-mu m wavelength region, By this optimum modulation with a w ave power of 1.0 W, the span-width of OFC was increased to 72 nm (= 9. 1 THz).