Control of the operation regimes of a passively modelocked fiber laser based on an intracavity polarizing fiber

Abstract

Interest on ultra-short optical pulse sources is rapidly growing due to the wide range of emerging areas where sup-picosecond pulses are providing new advances, from ultra-high-bit-rate optical communications (such as OFDM systems) to ultrafast spectroscopy and biomedical applications. Mode-locked fiber lasers are reliable, compact and cost-effective sources of stable sub-picosecond pulses [1]. Particularly, passive modelocking with fast saturable absorbers (SA), not limited by the speed of electronic signal generators, allows the generation of ultra-short pulses in the regimes of self-started passively modelocking (fast SA ML) and soliton modelocking [2]. On the other hand, Lyot filters based on the combination of in-line polarizers and birefringent fibers have been exploited for the generation of a multiwavelength emission regime [3]. Recently, polarizing (PZ) fibers with very low losses and ready to be spliced to standard fibers are commercially available. In this work we demonstrate that introducing a PZ fiber in the cavitiy of a SA modelocked laser (fig. 1.a) all the aforementioned regimes can be obtained by controlling the state of polarization at the input and output of the PZ fiber.