Demutiplexing of Nyquist-OTDM Signal Based on Temporal Magnification Aided Optical Sampling With Enhanced Performance

Demultiplexing of high-speed Nyquist optical time-division multiplexed (N-OTDM) signal requires ultra-narrow local sampling pulse to avoid the severe inter-symbol-interference (ISI) between each tributary. Unfortunately, generation of such narrow sampling pulse is difficult or usually need complex setup configure at the receiver side, which would cause ineffective cost in application scenarios such as short-reach optical communication or PON applications. In this paper, we propose and demonstrate demultiplexing of N-OTDM signal based on temporal magnification followed by coherent optical sampling to enable broader sampling pulsewidths while reducing the ISI. The target tributary of the N-OTDM signal is temporally magnified and further demultiplexed through coherent optical sampling using Gaussian-shaped or Nyquist-shaped pulses. With the aid of temporal magnification based on a time-lens, the sampling window can be extended during the coherent detection progress at the receiver side. Gaussian sampling pulses with a pulsewidth up to 10.4 ps are enabled for the demultiplexing of a 160 Gbaud N-OTDM signal. Compared with demultiplexing based on Nyquist pulses (i.e., coherent matched sampling) without temporal magnification, the proposed scheme features a better performance with pulsewidths greater than 6 ps. If temporal magnification is combined with coherent matched sampling, Nyquist sampling pulses with a pulsewidth up to 12.4 ps are made possible for the demultiplexing. Therefore, the proposed scheme based on temporal magnification could significantly release the pulsewidth requirement for N-OTDM demultiplexing while mitigating the ISI.