Multi-state optical flip-flop memory based on ring lasers coupled through the same gain medium

• Published in: Optics communications Vol. 270; no. 1; pp. 85 - 95
• Main Authors: Zhang, S., Lenstra, D., Liu, Y., Ju, H., Li, Z., Khoe, G.D., Dorren, H.J.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-02-2007; Elsevier Science
• Subjects: Coupled lasers; Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics; Exact sciences and technology; Flip-flop memories; Fundamental areas of phenomenology (including applications); Limit-cycle oscillators; Nonlinear optics; Optical bi-stability; Optical bistability, multistability and switching, including local field effects; Optical feedback; Optical multi-stability; Optics; Physics; Ring laser; Semiconductor optical amplifiers; Synchronization; Optical multi-stability; Semiconductor optical amplifiers; Limit-cycle oscillators; Optical bi-stability; Optical feedback; Flip-flop memories; Synchronization; Coupled lasers; Ring laser; Output power; Optical memory; Nonlinear dynamical systems; Optical bistability; Experimental study; Ring resonator; Feedback; Ring lasers; Optical multistability; Nonlinear optics
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2006.08.031

We investigate a system consisting of multiple ring lasers coupled by a single gain medium. All the ring lasers share a common feedback arm. The output power of an individual laser shows periodic oscillations as a function of time. The periodicity of the oscillation is determined by the ratio of the roundtrip times of the feedback arm and the ring cavity. In the case that two of such ring lasers are coupled, either their oscillation periodicities are synchronized, or the system is bi-stable. In the latter operation regime, the system can act as an optical flip-flop memory whose state be switched by injection of external light. The concept can be extended to multi-state operations; an eight-state optical flip-flop memory is experimentally demonstrated.