Experimental studies on WDM to TDM signal conversions using gigahertz electro-absorption modulators

Abstract

A method of optical signal conversions at high data rates from wavelength division multiplexing (WDM) signals to time division multiplexing (TDM) signals is demonstrated and studied experimentally using the cross-absorption effect of electro-absorption modulator (EAM). A multi-wavelength light source is designed and built up as a set of WDM carriers which are gated as the WDM pulse signals to be converted. The spectrum of the WDM signals covers more than 40 nm so that is proved that the wavelengths in the whole C+L band can be converted to a single wavelength at which the TDM signal is formed at the output of the system. The pulse width of the WDM signals which is input into the EAM device is about 2.586 ns. And the signal to noise ratio after conversion is about 7dB. It shows that EAM has strong noise immunity in the all-optical wavelength conversion experiment. And it is observed that the conversion of signals at the short wavelength shows higher conversion efficiency than the long-wavelength signals in the EAM device to a probe wavelength at the center of C band.