Real-time and ultrafast optical pulse quantization based on slicing the supercontinuum

All-optical analog-to-digital conversion is a paramount issue in modern science. How to implement real-time and ultrafast quantization to optical pulses with different intensities in an all-optical domain is a central problem. Here, we report a realtime demonstration of an all-optical quantization scheme based on slicing the supercontinuum in a nonlinear fiber. In comparison with previous schemes through off-line analysis of the power of different optical spectral components in the supercontinuum, this, to the best of our knowledge, is the first demonstration of such functionality online in the time domain.Moreover, the extinction ratio among the quantized outputs can exceed 10 d B, which further confirms the feasibility of the proposed quantization scheme. The current 3 bit resolution in the proof-of-principle experiment is limited by the current experimental condition, but it can be expected to be greatly enhanced through improving both the spectral width of the generated supercontinuum and the number of filtering channels used.

Ultrafast and real-time physical random bit extraction with all-optical quantization

Optical chaos generated by perturbing semiconductor lasers has been viewed,over recent decades,as an excellent entropy source for fast physical random bit generation(RBG)owing to its high bandwidth and large random fluctuations.However,most optical-chaos-based random bit generators perform their quantization process in the electrical domain using electrical analog-to-digital converters,so their real-time rates in a single channel are severely limited at the level of Gb/s due to the electronic bottleneck.Here,we propose and experimentally demonstrate an all-optical method for RBG where chaotic pulses are quantized into a physical random bit stream in the all-optical domain by means of a length of highly nonlinear fiber.In our proof-of-concept experiment,a 10-Gb/s random bit stream is successfully generated on-line using our method.Note that the single-channel real-time rate is limited only by the chaos bandwidth.Considering that the Kerr nonlinearity of silica fiber with an ultrafast response of few femtoseconds is exploited for composing the key part of quantizing laser chaos,this scheme thus may operate potentially at much higher real-time rates than 100 Gb/s provided that a chaotic entropy source of sufficient bandwidth is available.