Wavelength switching of erbium-doped fiber laser by using Mach-Zehnder interferometer and cavity loss control

A new wavelength-switchable erbium-doped fiber laser cavity is proposed and demonstrated. A Mach-Zehnder interferometer with controllable path-length difference was used in the laser cavity to tune the transmission peaks between two output paths of the interferometer. The erbium-doped fiber amplifier used in the laser cavity showed a tilted gain spectrum over the concerned wavelength range. A fiber bending scheme was used to switch the lasing wavelength taking advantage of the gain-tilt characteristics of the spectrum. The experimental result showed a stable four-wavelength lasing for each tuning and bending.