Tunable Passively $Q$-switched Erbium-Doped Fiber Laser With Carbon Nanotubes as a Saturable Absorber

TLDR

The paper presents an all‑fiber tunable, passively Q‑switched erbium‑doped fiber laser. The laser employs single‑wall carbon nanotube saturable absorbers deposited on fiber connectors and achieves tunability by axially straining a fiber Bragg grating mirror. The device reaches a low pump threshold of 11.1 mW and shows a self‑mode‑locking effect that can be suppressed by adding an unpumped EDF segment.

Abstract

An all-fiber tunable passively Q-switched erbium-doped fiber (EDF) laser is presented. Saturable absorbers are constructed by optically driven deposition of single-wall carbon nanotubes on fiber connectors. A low pump threshold of 11.1 mW is achieved. Self-mode-locking effect is also observed, and it could be suppressed by splicing an extra unpumped EDF into the laser ring cavity. The laser can be tuned by applying axial strain on the fiber Bragg grating which serves as a narrowband external mirror of the cavity.