Novel nanomaterials based saturable absorbers for passive mode locked fiber laser at 1.5 μm

Abstract

Compared with continuous wave lasers, ultrafast lasers have the advantages of ultra-short pulse width and ultra-high peak power, and have significant applications in optical communications, medical diagnostics, and precision machining. Saturable absorber (SA) technology is the most effective technique for the generation of ultra-fast lasers, which are based on artificial SAs and natural SAs. Among them, the semiconductor saturable absorber mirror (SESAM) has become the most commonly used form at present. Recently, basic research and application of nanomaterials such as carbon nanotubes (CNTs) and graphene have been developed rapidly. Researchers have found that nanomaterials exhibit extraordinary characteristics in ultrafast photonics, such as the low saturation intensity of CNTs, zero-band gap of graphene, and extremely high modulation depth of the topological insulator (TI) nano-films. Since graphene was first reported as an SA in 2009, many other nanomaterials have been successively explored, resulting in the rapid development of novel nanomaterial-based SAs. In this paper, we classified the nanomaterials used in SA mode-locking technology at 1.5 μm and reviewed their research progress with a particular focus on nonlinear optical properties, integration strategies, and applications in the field of ultrafast photonics

Purcell Enhanced Emission and Saturable Absorption of Cavity-Coupled CsPbBr3 Quantum Dots

“…This is because the saturable absorbers can concentrate transmitted light in the cavity nonlinearly, which modifies the optical losses of a cavity resulting in a change in the cavity quality factor. This saturable absorption has a number of important applications including optical switching, , optical bistability, and mode locking, , etc. To demonstrate saturable absorption, we increased the concentration of quantum dots by an order of magnitude (∼2.6 mg/mL quantum dots in toluene and 2% polystyrene).…”

Integration and Applications of Nanomaterials for Ultrafast Photonics

“…They came into researchers' sight relatively early compared to other nanomaterials and aroused widespread interests in areas including ultrafast lasers. CNTs, seamless cylinders with hollow structure and diameter on the nanometer level, [105,106] are typically categorized into two types: SWNTs and multi-walled carbon nanotubes based on their layers. Graphene consists of a monolayer of carbon atoms in the form of hexagonal crystal lattice.…”

Ultrafast pulse generation via magnetic topological insulator MnBi2Te4 nanosheets

“…In the past few years, topological insulators (TIs) have emerged as one of the most significant implications in the fields of condensed matter physics and material science [1][2][3][4] due to their exciting electronic and optical properties. In addition to providing a promising platform for realizing many novel and exotic quantum phenomena including quantum spin Hall effect 5 , topological surface states 6 , many interesting photonic and optoelectronic applications have been predicted or demonstrated such as terahertz modulators 7 , photodetector 8 , fiber lasers 9 , etc 10 . As narrow bandgap semiconductors, like Bi2Te3, Bi2Se3, and Sb2Te3, with a bandgap of 0.2 -0.3 eV 5 and high nonlinear optical response 11 , TIs can serve as an ideal SA in passive mode-locking fiber lasers operating in a wide wavelength range.…”