Abstract

Tm-doped fiber lasers, operating in the 2 μm eye-safe region (the absorbable band of human tissues) [1], have potential applications in molecular spectroscopy and medicine [1], where tuning the laser operating wavelength is highly desirable [1]. Tunable multiwavelength mode-locked fiber lasers have been widely reported in the 1 and 1.5 μm regions [2,3]. Ref. [4] studied the tunability of switchable dual- and triple-wavelength in the 2 μm region, but with an extra 70 m single-mode fiber into the cavity to obtain tunability. Here, we report a tunable multiwavelength nanotube mode-locked Tm-doped fiber laser achieved by inserting a polarization-maintaining isolator into two in-line polarization controllers (PCs). The laser can operate in dual-, triple- and four-wavelength mode-locking, by tuning the PCs. This compact and stable laser could be a convenient source for ultrafast spectroscopy and wavelength-division-multiplexing systems.

© 2017 IEEE