Ultrafast soliton delivered by miniaturized mode-locker with MoTe2 and core-expanded fiber.

ABSTRACT

Thermally expanded core (TEC) technology is an effective method of high-power fiber lasers. Miniaturization is also a major challenge for high-power lasers. We have proposed a miniaturized mode-locker based on TEC fiber and MoTe2-polyvinyl alcohol (PVA) film. The proposed mode-locker is consisting of two TEC ferrules, a piece of MoTe2-PVA film and a ceramic sleeve. The length of the proposed device is about 20 mm, and its outer diameter is about 2 mm. The relations between heating time, heating temperature, and mode field diameter (MFD) have been numerically simulated. The bending loss with respect to MFD has also been analyzed. The simulation results have revealed the trade-off relation between maximal tolerable intensity and low cavity loss, which means that there is an optimal MFD corresponding to optimal heating time and heating temperature. The proposed mode-locker has been applied in an integrated fiber laser, which has emitted ultrafast soliton with 3 times intensity larger than that of conventional sandwiched-type saturable absorber. The proposed mode-locker and fiber laser will find important applications in laser processing, laser ranging, and optical communication.