Experimental demonstration of a chaotic communication system with a switchable chaotic carrier wavelength based on two weak-resonant-cavity Fabry–Perot laser diodes

Abstract

Based on two weak-resonant-cavity Fabry–Perot laser diodes (WRC-FPLDs) with almost identical mode intervals, we propose and demonstrate experimentally, a chaotic communication system with switchable chaotic carrier wavelength. In such a scheme, a WRC-FPLD (called T-WRC-FPLD) subject to filtered feedback provided by a tunable optical filter (TOF) is taken as the transmitter, and the other WRC-FPLD (called R-WRC-FPLD) under optical injection from the T-WRC-FPLD is taken as the receiver. Through setting the central wavelength of the TOF and selecting the matched feedback strength, a desired mode in the T-WRC-FPLD can be chosen to stimulate and output a chaotic signal, whose central wavelength is determined by the central wavelength of the TOF. Thus, the T-WRC-FPLD under filtered feedback can provide a chaotic carrier with a switchable central wavelength. The chaotic signal output from the T-WRC-FPLD is sent to the R-WRC-FPLD and drives the R-WRC-FPLD for generating a chaotic signal. Under proper injection strength, high-quality chaotic synchronization between the T-WRC-FPLD and R-WRC-FPLD can be realized, and therefore the chaotic communication with switchable carrier wavelength can be implemented in this system. We adopt three different chaotic signals provided by three different modes in the T-WRC-FPLD as the chaotic carriers, respectively, and inspect the performances of the system. The experimental results show that, for the three cases, all the correlation coefficients between the T-WRC-FPLD and R-WRC-FPLD can be larger than 0.94 under optimized operating parameters. Via the high-quality chaotic synchronization between the T-WRC-FPLD and R-WRC-FPLD, a 5 Gb/s message encrypted in each chaotic carrier can be successfully decrypted at the receiver for the three cases, and the bit error ratios are all lower than 3.8 × 1 0 − 3 , which is the hard-decision forward error correction threshold.