10  Gbit/s Delay Modulation Using a Directly Modulated DFB Laser for a TWDM PON With Converged Services Invited

A 10 Gbit/s transmission with delay modulation is demonstrated using directly modulated lasers for time- and wavelength-division-multiplexed passive optical networks (TWDM PONs), and error-free performance is achieved over 20 km standard single-mode fiber with a small dispersion penalty. Delay modulation can also mitigate the crosstalk from the TWDM PON downstream signals to the coexisting RF video signal because of its small power spectral density at low frequencies. The carrier-to-crosstalk ratio of the RF video signal is improved by about 10 dB using delay modulation, instead of non-return-to-zero (NRZ) modulation, for 10 Gbit/s downstream transmissions in a TWDM PON. Furthermore, using lowpass-filtered 2.5 Gbit/s NRZ modulation and bandpass-filtered 10 Gbit/s delay modulation, dual-rate transmission is demonstrated for converged services in a TWDM PON. Experimental results exhibit 37.7 and 25.7 dB power budgets, respectively, for simultaneous 2.5 and 10 Gbit/s transmissions over 20 km standard single-mode fiber.