A Novel Optical Frequency-Hopping Scheme for Secure WDM Optical Communications

A novel optical frequency-hopping scheme in wavelength-division multiplexing (WDM) systems is proposed to achieve secure communications with high capacity. Frequency hopping is realized by the hopping of digital signals among different channels. In the proposed system, the signal from any source is separated into small segments in the time domain, and the segments are carried by more than one different-wavelength optical carrier. All the optical waves in the proposed WDM system are modulated by signals from two or more sources at different times. The signal from a certain source is also interference to signals from other sources. Hopping, synchronization, de-hopping, and routing are all digitally implemented in field-programmable gate array chips. The system is reconfigurable by software to adapt to different rates. Slow frequency hopping, fast frequency hopping, and intermediate frequency hopping are all available. A demonstration system is designed to support transmission speed from 0 to 10 Gb/s, and a video communication based on it is built to demonstrate the 1-Gb/s optical frequency-hopping system.