Spectrum-, pulsewidth-, and wavelength-switchable all-fiber mode-locked Yb laser with fiber based birefringent filter

Y S Fedotov,S M Kobtsev,R N Arif,C Mou,A G Rozhin,S K Turitsyn

doi:10.1364/oe.20.017797

Abstract

We examined methods of controlling the pulse duration, spectral width and wavelength of the output from an all-fiber Yb laser mode-locked by carbon nanotubes. It is shown that a segment of polarization maintaining (PM) fiber inserted into a standard single mode fiber based laser cavity can function as a spectral selective filter. Adjustment of the length of the PM fiber from 1 to 2 m led to a corresponding variation in the pulse duration from 2 to 3.8 ps, the spectral bandwidth of the laser output changes from 0.15 to 1.26 nm. Laser output wavelength detuning within up to 5 nm was demonstrated with a fixed length of the PM fiber by adjustment of the polarization controller.

Highlights

Laser mode locking by saturable absorbers (SA) based on single-wall carbon nanotubes (SWCNT) [1] has recently attracted a great deal of attention
An important advantage offered by SWCNT-based SA compared to semiconductor-based saturable absorber mirrors (SESAM) [2] is in their substantially simpler and cost efficient fabrication technology
We have investigated the control of spectral width and pulse duration of the SWCNT mode locked Yb fiber laser using fiber Lyot filter (FLF) [21]

Summary

Introduction

Laser mode locking by saturable absorbers (SA) based on single-wall carbon nanotubes (SWCNT) [1] has recently attracted a great deal of attention. We have investigated the control of spectral width and pulse duration of the SWCNT mode locked Yb fiber laser using fiber Lyot filter (FLF) [21]. Compensation of positive dispersion in all-fiber Yb laser cavities is done either by using specialty fibers such as micro-structured fiber [22], longperiod gratings in higher order mode fiber [23], tapered fiber [24], or hollow-core photonic bandgap fiber [25] or by means of chirped fiber Bragg gratings acting as spectral filters [26, 27] These methods provide possibility of control over pulse duration, they suffer from different drawbacks: e.g. effective splicing micro-structured fiber to standard fiber is still an issue; the tapered fiber core immediately exposed to the air may cause extra loss. With a fixed FLF, switchable output central wavelength has been obtained by tuning the PC

Experiment set-up

Results and discussion

Conclusion