Multiwavelength switching of an EDFL by using a fixed fiber-comb filter and a broadband tunable S-bent fiber filter

• Multiwavelength switching in an EDFL using two fiber filters is demonstrated.
• One filter is a Mach–Zender interferometer consisting of two concatenated tapers.
• The second is a broadband filter tunable by S-bending a fiber taper.
• The laser can switch between four, three, two, and one laser wavelength.

Multiwavelength Erbium-doped fiber ring lasers using two fiber filters inserted into the laser cavity is reported. The first fiber comb filter is a Mach–Zender interferometer consisting of two concatenated fiber tapers whose transmission bands determine the lasing wavelengths. The second filter is a tapered fiber which acts as a broadband fiber filter that reshapes the Erbium-doped fiber gain spectrum, and can be tuned by S-bending. Both filters are fabricated on the same fiber thus providing a cheap and very simple method to obtain tunable multiwavelength laser generation.