Pump-driven wavelength switching in an all-polarization-maintaining mode-locked fiber laser incorporating a CNT/PDMS saturable absorber

Mode-locked fiber lasers with wavelength tunability and dual-wavelength mode-locking capability have wide applications in nonlinear imaging, precision metrology and photonic sensing. Here, for the first time, we propose and experimentally demonstrate an environmentally stable all-polarization-maintaining (all-PM) fiber mode-locked laser without any intracavity filter and attenuator, whose mode-locking wavelength is switchable with the injected pump power. By increasing the pump power, the mode-locking wavelength switches from 1560-nm band to 1560/1530-nm dual-wavelength mode-locking, and finally to the 1530-nm band. The mechanism behind the phenomenon is well explained by the reverse saturable absorption induced intracavity loss variation. The proposed laser has a very concise configuration with only one integrated wavelength-division-multiplexer and a carbon nanotubes/polydimethylsiloxane (CNT/PDMS) saturable absorber (SA). The compact size, simple wavelength switching scheme as well as environmental stability makes it promising for practical applications.