High-energy, tunable-wavelengths, Q-switched pulse laser

An all fiber, wavelength tunable, Q-switched erbium-doped fiber laser (EDFL) based on a graphene saturable absorber (SA) and an unbalanced Mach–Zehnder interferometer (UMZI) has been demonstrated. The wavelengths of the Q-switched laser can be accurately tuned over a range of ~35 nm by inserting into the cavity an UMZI with a variable optical delay line (OVDL) in one arm, which acts as an optical beam filter into the cavity. The Q-switched pulse duration and the pulse energy have all been characterized. The maximum pulse energy of 36.9 nJ was obtained.