Generally speaking, the self-sweeping effect relies on the dynamical grating formed in active fiber. Here, the normal self-sweeping was generated in a ytterbium-doped fiber which serves as a fiber saturable absorber and is introduced to the laser cavity by a circulator in this experiment. The sweeping rate and the sweeping range alter as usual, both of which can be controlled by the pump power. Further, a new self-pulse signal is observed and discussed, which shows both the grating feature and saturable absorption of YDFSA. Our work provides a new self-sweeping way and can act as a platform to further deeply study this effect.

We demonstrate a passively Q-switched ytterbium-doped fiber laser based on black phosphorus (BP) flakes covered microfiber. The BP saturable absorber is fabricated by sandwiching a microfiber between two pieces of polydimethylsiloxane supported BP flakes film, which is prepared by the mechanical exfoliation method. In this case the BP flakes can be well protected from the action of air and moisture. By incorporating BP flakes covered microfiber into a ytterbium-doped ring fiber laser, stable and reliable Q-switched operation at 1064 nm can be realized via interaction between few-layers BP flakes and the evanescent field of the laser. The laser allows Q-switched pulse generation with a repetition rate in the range of 26-76 kHz and a pulse duration in the range of 5.5-2.0 μs, by varying the pump power from 38 mW to 100 mW.

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Synthetic mesh lattice (SML) with temporally controlled potential is a versatile platform for realizing wave dynamics associated with physical areas of optics and quantum physics. Here, discrete optics in one-dimensional synthetic photonic lattice is investigated systematically, in which the light behavior is highly analogous to that in evanescently coupled one-dimensional discrete waveguides. Such a synthetic dimension is constructed with position-dependent periodic effective gauge fields based on the Aharonov–Bohm effect arising from the phase accumulation of the fiber loops. By tuning the phase accumulation and coupling coefficient of the coupler, the band translation and gap property can be modulated, which further results in the impulse and tailored Gaussian wave packet responses as well as Talbot recurrences. In addition, Bloch oscillations and Anderson localization can also be obtained when the phase accumulations are linearly changed and weakly modulated in a random manner, respectively. The periodic effective gauge fields configuration in our protocol enables SML to be a research platform for one-dimensional dynamically modulated elements or even non-Hermitian waveguides.

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