A COMPENSATION METHOD FOR DISPERSION-INDUCED 3RD-ORDER INTERMODULATION DISTORTION USING AN ETALON

A method to compensate dispersion-induced third-order intermodulation distortion (IM3(CD)) in subcarrier multiplexing (SCM) optical transmis sion systems is proposed. It is confirmed theoretically and experiment ally that IM3(CD) can be compensated by interference-induced third-ord er intermodulation distortion (IM3(IN)). Simple analytic expressions o f IM3(CD) and IM3(IN) are derived from the same expression of optical electric field which includes exact phase term taking into account the phase of laser chirp. From the theoretical analyses, we clarified the conditions of IM3(CD)-compensation. IM3(IN) can be easily generated b y an etalon which is a kind of interferometer and a optical glass plat e. More than 30 dB of IM3(CD)-compensation was achieved, and IM3(CD)-c ompensation was achieved regardless of the transmission distance by ad justing tilt angle of the etalon. Using this method, high quality sign al transmission can be realized even though the wavelength of laser di ode (LD) is not coincident with the fiber zero dispersion wavelength.