We provide a perspective overview of the emerging field of nonlinear optics in multimode optical fibers. These fibers enable new methods for the ultrafast light-activated control of temporal, spatial, and spectral degrees of freedom of intense, pulsed beams of light, for a range of different technological applications.

Multimode nonlinear fiber optics, a spatiotemporal avenue

Ultrafast photonics application of graphdiyne in the optical communication region

Technology and applications

The significance of silver nanostructures has been growing considerably, thanks to their ubiquitous presence in numerous applications, including but not limited to renewable energy, electronics, biosensors, wastewater treatment, medicine, and clinical equipment. The properties of silver nanostructures, such as size, size distribution, and morphology, are strongly dependent on synthesis process conditions such as the process type, equipment type, reagent type, precursor concentration, temperature, process duration, and pH. Physical and chemical methods have been among the most common methods to synthesize silver nanostructures; however, they possess substantial disadvantages and short-comings, especially compared to green synthesis methods. On the contrary, the number of green synthesis techniques has been increasing during the last decade and they have emerged as alternative routes towards facile and effective synthesis of silver nanostructures with different morphologies. In this review, we have initially outlined the most common and popular chemical and physical methodologies and reviewed their advantages and disadvantages. Green synthesis methodologies are then discussed in detail and their advantages over chemical and physical methods have been noted. Recent studies are then reviewed in detail and the effects of essential reaction parameters, such as temperature, pH, precursor, and reagent concentration, on silver nanostructure size and morphology are discussed. Also, green synthesis techniques used for the synthesis of one-dimensional (1D) silver nanostructures have been reviewed, and the potential of alternative green reagents for their synthesis has been discussed. Furthermore, current challenges regarding the green synthesis of 1D silver nanostructures and future direction are outlined. To sum up, we aim to show the real potential of green nanotechnology towards the synthesis of silver nanostructures with various morphologies (especially 1D ones) and the possibility of altering current techniques towards more environmentally friendly, more energy-efficient, less hazardous, simpler, and cheaper procedures.

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A review on the green and sustainable synthesis of silver nanoparticles and one-dimensional silver nanostructures.

Generation, optimization, and application of ultrashort femtosecond pulse in mode-locked fiber lasers

We demonstrate an all-fiber mode locked laser based on hybrid structure of multimode fiber saturable absorber (SA) that can realize both conventional soliton and stretched-pulse states. Stable 16.44 MHz conventional soliton pulses are achieved by injecting 80 mW threshold pump power. By increasing the incident pump power to 420 mW, the laser evolves from soliton operation into stretched-pulse mode locking state. 310 fs stretched-pulse are obtained with the same repetition rate as the soliton pulses. The center wavelength and its 3 dB spectrum bandwidth are 1603 nm and 14.2 nm, respectively. For the first time, we experimentally confirm transition between conventional soliton and stretched-pulse in 1.5 μm mode-locked fiber laser by introducing multimode optical fiber SA. Moreover, the maximum single pulse energy of nearly 1 nJ is achieved. Such all-fiber mode-locked lasers based on hybrid structure of multimode fiber are attractive for practical applications without damage and the limitation of life time.

/pdf/ultrafast-soliton-and-stretched-pulse-switchable-mode-locked-1ocl0epcw2.pdf

Ultrafast soliton and stretched-pulse switchable mode-locked fiber laser with hybrid structure of multimode fiber based saturable absorber

Generation of dark solitons in erbium-doped fiber laser based on black phosphorus nanoparticles

A novel approach to saturable absorber (SA) formation is presented by taking advantage of the mode coupling property of excessively tilted fiber grating (Ex-TFG). Stable mode-locked operation can be conveniently achieved based on the interaction between Ex-TFG coupled light and deposited ferroferric-oxide (Fe3O4) nanoparticles. The central wavelength, bandwidth and single pulse duration of the output are 1595 nm, 4.05 nm, and 912 fs, respectively. The fiber laser exhibits good long-term stability with signal-to-noise ratio (SNR) of 67 dB. For the first time, to the best of our knowledge, Ex-TFG based Fe3O4 SA for mode-locked fiber laser is demonstrated.

Excessively tilted fiber grating based Fe3O4 saturable absorber for passively mode-locked fiber laser.

https://iopscience.iop.org/article/10.1088/1612-202X/aae050/pdf

Experimental observation of bound solitons with a nonlinear multimode interference-based saturable absorber

We demonstrate a mode-locked all-fiber Er-doped fiber laser using the structure of a step-index multimode fiber and a graded index fiber as a new saturable absorber (SA) based on nonlinear multimode interference. By bending the SA to a certain state, stable soliton pulses are obtained at a pump threshold of 65 mW. The oscillator generates soliton pulses at 1598 nm with a spectral bandwidth of 3.4 nm, 960 fs duration and a fundamental repetition rate of 9.789 MHz. The output power of 24 mW is achieved at the maximum pump power of 700 mW, corresponding to a single pulse energy of 2.44 nJ. To the best of our knowledge, this is the first time anyone has achieved the highest single pulse energy in a fiber laser with the SA at 1.5 µm to date. Moreover, the impact of diverse mode field diameters of graded index fiber on mode-locking behavior will also be discussed.

Fengyan Zhao

Papers

Ultrafast soliton and stretched-pulse switchable mode-locked fiber laser with hybrid structure of multimode fiber based saturable absorber

Generation of dark solitons in erbium-doped fiber laser based on black phosphorus nanoparticles

Excessively tilted fiber grating based Fe3O4 saturable absorber for passively mode-locked fiber laser.

Experimental observation of bound solitons with a nonlinear multimode interference-based saturable absorber

High-energy solitons generation with a nonlinear multimode interference-based saturable absorber