Two-dimensional（2D） materials have emerged as attractive mediums for fabricating versatile optoelectronic devices. Recently, few-layer molybdenum disulfide（MoS2）, as a shining 2D material, has been discovered to possess both the saturable absorption effect and large nonlinear refractive index. Herein, taking advantage of the unique nonlinear optical properties of MoS2, we fabricated a highly nonlinear saturable absorption photonic device by depositing the few-layer MoS2 onto the microfiber. With the proposed MoS2 photonic device, apart from the conventional soliton patterns, the mode-locked pulses could be shaped into some new soliton patterns, namely,multiple soliton molecules, localized chaotic multipulses, and double-scale soliton clusters. Our findings indicate that the few-layer MoS2-deposited microfiber could operate as a promising highlynonlinear photonic device for the related nonlinear optics applications.
Ai-Ping LuoMeng LiuXu-De WangQiu-Yi NingWen-Cheng XuZhi-Chao Luo
As the typical material of two-dimensional transition metal dichalcogenides（TMDs）, few-layered MoS2 possesses broadband saturable absorption and a large nonlinear refractive index, which could be regarded as a promising candidate for dual-function photonic device fabrication. In this work, the coexistence of a bound soliton and harmonic mode-locking soliton was demonstrated in an ultrafast fiber laser based on a MoS2-deposited microfiber photonic device. Through a band-pass filter, each multi-soliton state was investigated separately. The bound soliton has periodic spectral modulation of 1.55 nm with a corresponding pulse separation of 5.16 ps.The harmonic mode-locking soliton has the repetition rate of 479 MHz, corresponding to the 65th harmonic of the fundamental repetition rate. The results indicated that there exist more possibilities of different multi-soliton composites, which would enhance our understanding of multi-soliton dynamics.
We report on the generation of Q-switched and Q-switched mode-locked （QML） pulses in an erbium-doped fiber ring laser by using a polyvinyl alcohol （PVA） -based gold nanorod （GNR） saturable absorber （SA）. The PVA- based GNR SA has a modulation depth of -4.8% and a non-saturable loss of -26.9% at 1.5 μm. A Q-switched pulse train with a repetition rate varying from 18.70 to 39.85 kHz and a QML pulse train with an envelope repetition rate tuning from 20.31 to 31.50 kHz are obtained. Moreover, the lasing wavelengths of the Q-switched pulses can be flexibly tuned by introducing a narrow bandwidth, tunable filter into the laser cavity. The results demonstrate that the GNRs exhibit good optical performance and can find a wide range of applications in the field of laser technology.
Searching for an ultrahigh-repetition-rate pulse on the order of hundreds of gigahertz(GHz) is still a challenging task in the ultrafast laser community. Recently, high-quality silicon/silica-based resonators were exploited to generate a high-repetition-rate pulse based on the filter-driven four-wave mixing effect in fiber lasers. However,despite their great performance, the silicon/silica-based resonators still have some drawbacks, such as single waveband operation and low coupling efficiency between the fiber and resonators. To overcome these drawbacks,herein we proposed an all-fiber broadband resonator fabricated by depositing the graphene onto a microfiber knot. As a proof-of-concept experiment, the graphene-deposited broadband microfiber knot resonator(MKR)was applied to Er-and Yb-doped fiber lasers operating at two different wavebands, respectively, to efficiently generate hundreds-of-GHz-repetition-rate pulses. Such a graphene-deposited broadband MKR could open some new applications in ultrafast laser technology, broadband optical frequency comb generation, and other related fields of photonics.
MENG LiuRUI TANGAI-PING LuoWEN-CHENG XuZHI-CHAO LUO
Two-dimensional（2D） materials have been regarded as a promising nonlinear optical medium for fabricating versatile optical and optoelectronic devices. Among the various photonic applications, the employment of 2D materials as nonlinear optical devices such as saturable absorbers for ultrashort pulse generation and shaping in ultrafast lasers is one of the most striking aspects in recent years. In this paper, we review the recent progress of 2D materials based pulse generation and soliton shaping in ultrafast fiber lasers, and particularly in the context of 2D materials-decorated microfiber photonic devices. The fabrication of 2D materials-decorated microfiber photonic devices, high performance mode-locked pulse generation, and the nonlinear soliton dynamics based on pulse shaping method are discussed. Finally, the challenges and the perspective of the 2D materials-based photonic devices as well as their applications are also discussed.
The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller （PC）. At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate.
