102 research outputs found
Forecasting the chaotic dynamics of external cavity semiconductor lasers
Chaotic time series prediction has been paid intense attention in recent years due to its important applications. Herein, we present a single-node photonic reservoir computing approach to forecasting the chaotic behavior of external cavity semiconductor lasers using only observed data. In the reservoir, we employ a semiconductor laser with delay as the sole nonlinear physical node. By investigating the effect of the reservoir meta-parameters on the prediction performance, we numerically demonstrate that there exists an optimal meta-parameter space for forecasting optical-feedback-induced chaos. Simulation results demonstrate that using our method, the upcoming chaotic time series can be continuously predicted for a time period in excess of 2 ns with a normalized mean squared error lower than 0.1. This proposed method only utilizes simple nonlinear semiconductor lasers and thus offers a hardware-friendly approach for complex chaos prediction. In addition, this work may provide a roadmap for the meta-parameter selection of a delay-based photonic reservoir to obtain optimal prediction performance
Physical-layer key distribution using synchronous complex dynamics of DBR semiconductor lasers
Common-signal-induced synchronization of semiconductor lasers with optical
feedback inspired a promising physical key distribution with
information-theoretic security and potential in high rate. A significant
challenge is the requirement to shorten the synchronization recovery time for
increasing key rate without sacrificing operation parameter space for security.
Here, open-loop synchronization of wavelength-tunable multi-section distributed
Bragg reflector (DBR) lasers is proposed as a solution for physical-layer key
distribution. Experiments show that the synchronization is sensitive to two
operation parameters, i.e., currents of grating section and phase section.
Furthermore, fast wavelength-shift keying synchronization can be achieved by
direct modulation on one of the two currents. The synchronization recovery time
is shortened by one order of magnitude compared to close-loop synchronization.
An experimental implementation is demonstrated with a final key rate of 5.98
Mbit/s over 160 km optical fiber distance. It is thus believed that
fast-tunable multi-section semiconductor lasers opens a new avenue of high-rate
physical-layer key distribution using laser synchronization.Comment: 13 pages, 5 figure
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