Passive Q-Switching of an All-Fiber Laser Using WS <sub>2</sub>-Deposited Optical Fiber Taper

Abstract

Abstract: We demonstrate the passive Q-switching operation of an erbium-doped fiberlaser using a few-layer WS 2 -based saturable absorber with evanescent field interaction.WS 2 flakes have been synthesized via a liquid-phase exfoliation method, and an opticalfiber taper was selected as a light-material template that causes to achieve a long inter-action length of the evanescent wave. Subsequently, the prepared solution was opticallydeposited around the 3-mm interaction length of the fabricated optical fiber taper with a5- m waist diameter. The proposed Q-switched fiber laser based on the WS 2 -depositedfiber taper saturable absorber could generate stable output pulses at 1565 nm, with apulsewidth ranging from 1.3 to 3 s and a repetition rate of 33–108 kHz.Index Terms: Tungsten disulfide, nonlinear optical materials, saturable absorber,Q-switched fiber laser. 1. Introduction Q-switched fiber lasers have attracted great attention owning to the relatively large pulse energyat relatively low repetition rates and pulse width of the scale from microsecond to nanosecond.These short pulsed lasers have extensive applications in material processing, telecommunica-tions, medicine, and sensing [1]. Q-switched pulses can be obtained via active or passiveQ-switching techniques. Passively Q-switched lasers have several advantages such as sim-plicity, compactness, and low cost compared to that of active techniques which require anactive optical component such as electro-optic or acousto-optic modulators [2].Passive Q-switched technique of lasers based on saturable absorber (SA) is the well-knownand most effective method to achieve Q-switching operation which has been widely investigated.In the past few decades, researchers investigated various kinds of SA materials, including toxicdye materials [3], semiconductor saturable absorber mirrors (SESAMs) [4], carbon nanotubes(CNTs) [5], and graphene [6], [7]. Although the SESAMs are very mature and commercialized,