Pseudorandom wavelength hopping based on chaos: Experimental generation and synchronization

This paper proposes and demonstrates a scheme for generating pseudo-random wavelength hopping sequences in semiconductor lasers by using chaotic dynamics. The system consists of a wavelength tunable light source, a nonlinear wavelength element, and a delayed opto-electric feedback. By feeding back the filter output signal to the light source to control the lasing wavelength, it is possible to achieve periodic or chaotic wavelength variation patterns with a wide variation range covering several longitudinal modes. In experiments, wavelength hopping among up to 10 modes was observed with the hopping frequency about 100 MHz. Synchronization of the wavelength hopping in two separate lasers is performed by coupling part of the feedback signal of one laser into the feedback of a second laser. Synchronization was observed between the on-off intensity modulation patterns of each pair of corresponding longitudinal laser modes.