Ultrafast lasers generating high repetition rate ultrashort pulses through various modelocking methods can benefit many important applications including communication, materials processing, astronomical observation, etc. For decades, mode-locking based on dissipative four-wave-mixing (DFWM) has been fundamental in producing pulses with repetition rates on the order of gigahertz (GHz), where multiwavelength comb filters and long nonlinear components are elemental. Recently, this method has been improved using filterdriven DFWM, which exploits both the filtering and nonlinear features of silica microring resonators. However, the fabrication complexity and coupling loss between waveguides and fibers are problematics. In this study, we demonstrate a tens to hundreds of gigahertz stable pulsed all-fiber laser based on the hybrid plasmonic microfiber knot resonator device. Unlike previously reported pulse generation mechanisms, the operation utilizes the nonlinearpolarization-rotation (NPR) effect introduced by the polarization-dependent feature of the device to increase intracavity power for boosting DFWM mode-locking, which we term NPR -stimulated DFWM. The easily-fabricated versatile device acts as a polarizer, comb filter, and nonlinear component simultaneously, thereby introducing a novel application of microfiber resonator devices in ultrafast and nonlinear photonics. We believe that our work underpins a significant improvement in achieving practical low-cost ultrafast light sources.

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Carbon nanotubes (CNTs) possess remarkable nonlinear optical properties; a particular application is to function as a mode locker used in ultrafast fiber lasers to produce ultrashort optical pulses. Various types of CNT saturable absorbers (SAs) and ultrafast fiber lasers have been demonstrated. In this review, typical fabrication process and development of CNT SAs are discussed and we highlight the recent investigation and progress of state-of-the-art ultrafast fiber lasers covering GHz, bidirectional ultrafast fiber lasers, vectorial mode fiber lasers, comb systems, and mode-locking dynamics. Our perspectives of ultrafast fiber lasers based on CNT SAs are given finally.

We experimentally demonstrate a passively harmonic mode locked (PHML) Er-doped fiber laser with pump power efficiency up to 17 MHz/mW operating at L-band based on single walled carbon nanotubes polyvinyl alcohol (SWCNTs-PVA) film. Under 233 mW pump power, the stable pulse train at 1594.97 nm with 40.5 dB side mode suppression ratio (SMSR) and 742 fs pulse duration is obtained at a repetition rate of 1.923 GHz, corresponding to 170 th harmonic of the fundamental frequency. Under optimized intracavity conditions, the pulses frequency is able to scale up to 2.415 GHz with a high level of 40 dB SMSR, which to the best of our knowledge, is the highest value yet reported from a L-band PHML fiber laser incorporating SWCNTs as saturable absorber (SA). Such high repetition rate and stable fiber laser operating at L band may be desirable for various applications. Index Terms-mode locked fiber lasers, mode locking, nanomaterials I. INTRODUCTION RESENT research activities on ultrashort pulse fiber lasers with up to GHz range repetition rate have been extensively explored on account of their potential applications in optical frequency metrology [1], high speed optical sampling [2] and modern optical communication system [3]. Especially, for the modern optical communication system, the conventional Cband telecommunication window has been incapable of supplying the demand of persistent increasing of communication capacity. For addressing the problem, extending optical telecommunication region to L band is a key issue. Therefore, there is no doubt that investigating L-band fiber laser with high repetition rate via PHML method is of great importance. It is already widely acknowledged that active mode locking [4], short cavity [5] as well as PHML [6] have been considered as effective methods to achieve high repetition rate pulses. In a PHML laser, when high pump light launches into the laser Manuscript received XXXXXX. We would like to express our gratitude to the National Natural Science Foundation of China (NSFC) (61605107,61975107) and the open fund (Grant No. IPOC2017B010

AbstractWe report experimental observation of polarization attractors in the form of vector dissipative solitons from a carbon nanotube mode locked fiber laser. At a time scale of 14–14,000 roundtrips, the typical polarization locked vector solitons, and other appealing attractors are shown. In addition, we observe the vector dissipative solitons operated in dual-wavelength regime with central wavelength of 1533 and 1557 nm which can be related to a fixed point polarization attractor. The results unveiled complex oscillatory behavior of dissipative solitons in the polarization domain which may help understand laser physics, nonlinear optics. The demonstrated work may underpin a new type of high energy laser source leading to possible applications in nanoparticle manipulation, micromachining, spectroscopy etc.