We demonstrate a stable, picosecond fiber laser mode-locked by cesium lead halide perovskite quantum dots (CsPbBr₃-QDs). The saturable absorber is produced by depositing the CsPbBr3-QDs nanocrystals onto the endface of a fiber ferrule through light pressure. A balanced two-detector measurement shows that it has a modulation depth of 2.5% and a saturation power of 17.29 MW/cm². After incorporating the fabricated device into an Er³⁺-doped fiber ring cavity with a net normal dispersion of 0.238 ps², we obtain stable dissipative soliton with a pulse duration of 14.4 ps and a center wavelength at 1600 nm together with an edge-to-dege bandwidth of 4.5 nm. The linear chirped phase can be compensated by 25 m single mode fiber, resulting into a compressed pulse duration of 1.046 ps. This experimental works proves that such CsPbBr3-QDs materials are effective choice for ultrafast laser operating with devious mode-locking states.

Dissipative solitons emerge as stable pulse solutions of nonintegrable and nonconservative nonlinear physical systems, owing to a balance of nonlinearity, dispersion, and loss/gain. A considerable research effort has been dedicated to characterizing amplitude and phase evolutions in the spatiotemporal dynamics of dissipative solitons emerging from fiber lasers. Yet, the picture of the buildup process of dissipative solitons in fiber lasers is incomplete in the absence of corresponding information about the polarization evolution. Here, we characterize probabilistic polarization distributions in the buildup of dissipative solitons in a net-normal dispersion fiber laser system, mode-locked by single-wall carbon nanotubes. The output optical spectra under different pump powers are filtered by a tunable filter, and are detected by a polarization state analyzer. The laser system operates from random amplified spontaneous emission into a stable dissipative soliton state as the cavity gain is progressively increased. Correspondingly, the state of polarization of each spectral wavelength converges towards a fixed point. To reveal the invariant polarization relationship among the various wavelength components of the laser output field, the phase diagram of the ellipticity angle and the spherical orientation angle is introduced. We find that, within the central spectral region of the dissipative soliton, the state of polarization evolves with frequency by tracing a uniform arc on the Poincaré sphere, whereas in the edges of the dissipative soliton spectrum, the state of polarization abruptly changes its path. Increasing cavity gain leads to spectral broadening, accompanied by a random scattering of the state of polarization of newly generated frequencies. Further increases of pump power result in dissipative soliton explosions, accompanied by the emergence of a new type of optical polarization rogue waves. These experimental results provide a deeper insight into the transient dynamics of dissipative soliton fiber lasers.

All-optical controlling provides burgeoning, precise and compact access in photonics and optoelectronics with tunable performance. Through tuning the physical parameters of optical-controlled devices, such as effective index, bandwidth and dispersion, the output characteristics of free-running laser can be manipulated for widespread applications in spectroscopy and laser biology. Among which the flexible optical-thermal tunability of graphene introduces an advantageous avenue for the enhancement of photosensitivity of optical-controlled devices to efficiently regulate laser properties. Here, we fabricate an optical-controllable fiber filter based on a graphene-assisted micro-fiber Bragg grating, whose wavelength can be linearly tuned by controlling pump light, and a tuning step of 3.1 pm is achieved. By cooperating it with a fiber laser operating at a Q-switched mode-locked state, the lasing wavelength is all-optically controlled with a linear tuning sensitivity of 23.5 pm/mW. Considering the optical controlling performances, such a wavelength-tunable fiber laser may find potential applications in all-optical computing, all-optical logic gating and generation of microwave source.

An ultra-widely tunable acousto-optic add-drop filter is proposed and demonstrated based on the acoustically-induced polarization conversion of cladding-etched single-mode fiber, which covers wavelengths from 1081 nm to 1582 nm with a tuning band larger than 500 nm. The constructed filter has reconfigurable band-pass and band-rejection filtering characteristics, and obtains the advantages of ultra-wide wavelength tuning range, fast tuning speed, simple fabrication and zero frequency shift. It has potential applications in the fields of WDM communication, ultra-wide tunable laser, signal processing, swept-source optical coherence tomography (SS-OCT) and wideband spectroscopy.

Acoustically-induced fiber gratings (AIFGs) can be employed as the main device to achieve wide-range, time-linear, and fast wavelength tunability of various lasers, due to their fast spectral response during the high-speed tuning process. Herein, we propose a wideband fast-tunable fiber laser that consists of a semiconductor optical amplifier (SOA) and an AIFG that induces the acousto-optical polarization conversion effect. Its laser dynamics during the tuning process are revealed. The rate equation of the inversion population is used to theoretically predict the laser intensity evolution during the dynamical tuning process. The simulation results show that the relaxation oscillation and huge laser pulse during the tuning process can be suppressed by shortening the upper energy-level lifetime of the gain medium. In order to experimentally reveal the tuning dynamics, the output intensity evolution of the tunable laser is monitored. The lasing tuning response time reaches ∼200 μs, whose value has approached that of the AIFG. Due to the short energy-level lifetime of the SOA, the laser relaxation oscillation during the dynamical tuning process can be successfully suppressed, which coincides well with the simulation prediction. This work creates an avenue to understand the acousto-optical tuning dynamics profoundly. It also provides guides to maximize the speed advantage of this tuning mechanism in various tunable laser cavities.

Researches on high coherence light sources always pursue fast tuning speed, linear tunability and persistence of narrow linewidths at different tuning channels. Fortunately, acousto-optical interaction (AOI) can be employed in the fast management of the lasing wavelength. Herein, we propose a fast tunable narrow-linewidth fiber laser assisted by the acoustically-induced polarization selection in dispersion compensation fiber (DCF). The lasing wavelength is determined by the acoustically-induced band-pass grating in DCF. The large dispersion slope of the DCF suppresses the bandwidth of the TM ₀₁ peak to be less than 1 nm. The acousto-optic-controlled polarization conversion effectively restrains the acousto-optic frequency shift. With side longitudinal mode suppressions induced by the combintion of the self-injection feedback and saturable absorption filtering, the output laser successfully achieves the narrow-linewdith operation and owns a low relative intensity noise floor of −135 dB/Hz. By controlling the acoustic-wave frequency, the laser can be linearly tuned with a large wavelength range (over 20 nm, linear fitting R ² reaches 0.99781), and the laser linewidths remain about ∼2 kHz in different tuning channels. The laser tuning dynamics under the acousto-optical controlling are experimentally revealed, and the lasing tuning response time is ∼800 μs.