Switchable multi-wavelength and tunable waveband fiber laser based on a thermal sensitive filter

In this work, a waveband tunable and switchable multi-line ring-cavity fiber laser is presented. Here, the losses of the cavity are controlled by means of a variable optical attenuator (VOA) and a thermal sensitive interferometric filter, which was formed by a stack of 3 layers at the tip of an optical fiber and a long thermal sensitive sleeve. Thus, the laser can emit single-, dual-, triple-, quadruple-, quintuple-and sextuple-wavelength emissions which can be switched by adjusting the VOA. Moreover, the laser waveband can be tuned by varying the temperature of the filter. Here, it is shown that with this setup a waveband tuning resolution of similar to 1.37 nm degrees C-1 within the range from 1527.52 to 1534.40 nm can be achieved.