Phase-shift-keying of actively mode-locked erbium-doped fiber ring laser by using an inherent delay-locked-loop

We demonstrate the inherent and continuous phase-shift-keying (PSK) of optical pulse-train generated from an actively mode-locked erbium-doped fiber ring laser by using a newly designed microwave delay-locked-loop circuit. The maximum PSK depth of optical pulse-train repeated at 500 MHz can be up to 340/spl deg/ (/spl sim/1.9 /spl pi/).