Switchable dual-wavelength CNT-based Q-switched using arrayed waveguide gratings (AWG)

In this paper, a dual-wavelength synchronously pulsed fiber laser Q-switched by carbon nanotube-based saturable absorber with switchable wavelength spacing enabled using arrayed waveguide grating (AWG) is proposed and demonstrated. By just switching the channels of the AWG, discrete tuning in wavelength spacing of the dual-wavelength Q-switched laser operation can be attained over several nanometers, ranging from 1.6 to 4.0 nm in a stable dual-wavelength regime without employing any modulation technique or intracavity spectral filters. Our experimental results show that the fiber laser can generate Q-switched microsecond pulses with a wide repetition rate range, starting from 12.0 kHz to a maximum value of 54.9 kHz. This proposed system is also reasonably simple to realize at low cost.