Method and device for encoding data into high speed optical train

Abstract

A device for encoding data into high speed optical train includes N data encoding branches, each having a dual-mode laser, generating at the beat frequency f, and an external modulator. Each dual mode laser includes a laser structure having two sections formed on the same substrate which simultaneously operate at different longitudinal modes. Each section has a complex coupled (gain-coupled or loss-coupled) grating which is formed by deep etching through the multi-quantum well structure, ensuring no substantial interaction between lasers. The sections have common active medium and shared optical path and provide mutual light injection into each other. Signals from the branches are put through a variable delay line, introducing phase shifts between the signals, and compressed in the optical compressor. Thus, N short pulse optical trains are formed. The phase shifts between the signals are adjusted so that, when the trains are further combined in the optical combiner, they interleave in a precise timing to form one combined optical pulse train of frequency Nf. Thus, encoding of data at a speed, which is much higher than the speed of the external modulator, is achieved. The corresponding method of encoding data is also provided.