Highly Efficient and Robust Broadband Nano‐VO₂(M) Saturable Absorber for Nonlinear Optics and Ultrafast Photonics

Abstract

The metal‐to‐insulator transition behavior and the fast and reversible phase transition behavior in vanadium dioxide (VO2) have attracted widespread attention to study various potential applications. However, few studies have been focused on its nonlinear properties and applications in the pulsed laser field. Here, the authors report the design and synthesis of monoclinic nano‐VO2(M) saturable absorber with broadband absorption which spans the entire near‐infrared region, and high optical nonlinearity which is much higher than those of carbon nanomaterials, gold nanocrystals, and Cu1.8S nanocrystals, as measured in the same condition. The nano‐VO2(M) optical modulators are integrated into the fiber laser cavities, and demonstrate wideband Q‐switching operations at 1, 1.56, and 2 µm and mode‐locking operation at 2 µm, with a pulse duration of 765 fs. This work first reveals the outstanding nonlinear optical properties of nano‐VO2(M) and lays a foundation for its development in advanced nonlinear optical and photonic devices.

Q-switched fiber laser operating at 1560 nm modulated by Cr3C2 film

“…Passively Q-switched EDFLs have been intensively investigated by using different kinds of SAs, such as semiconductor saturable absorber mirrors (SESAMs), nonlinear polarization rotation (NPR), mesoporous carbon nanospheres (MCNs), black phosphorus (BP), transition metal oxide, and transition metal * Author to whom any correspondence should be addressed. dichalcogenides [11][12][13][14][15][16][17][18]. However, SESAMs have limited operating bandwidth with complex preparation process.…”

Composition engineering of AZO films for controlled photon–electron conversion and ultrafast nonlinear optical behavior

“…The above two processes have been applied to the fields of mode-locked lasers and laser protection with excellent optical limiting performance, respectively. [17][18][19][20][21][22] The above nonlinear absorption mechanisms can also be dominated by the absorption cross-section-when the excited state absorption cross-section is smaller (or larger) than the ground state absorption cross-section, the sample will exhibit SA behavior (or RSA behavior). [23][24][25][26] In addition, the responsivity and modulation depth of nonlinear photonic devices are affected by the lifetime of carriers at virtual levels.…”

CsPbBr3 Perovskite Nanocrystals for a Q-Switched Pulsed Fiber Laser in the C-Band Region

“…Pulsed lasers are promising tools in many fields of scientific research and industry because of their favorable properties of large pulse energy and high peak power, including biomedicine, spectroscopy, optical communications, laser processing, and others. − In general, the passive Q-switching technique is one of the most practical for generating pulsed lasers due to its many advantages. , In such passive Q-switching lasers, saturable absorbers (SAs) are employed as nonlinear optical modulators, whose transmittance increases as the input laser intensity increases, thus allowing continuous wave lasers into pulsed lasers. Over the past decades, numerous efforts have been dedicated to developing SA materials including graphene, , carbon nanotubes (CNTs), , topological insulators (TIs), , transition-metal dichalcogenides (TMDs), , transition-metal oxides (TMOs), − black phosphorus (BP), and semiconducting polymer dots (Pdots). , However, these SAs suffer from their inherent limitations. For example, graphene suffers from relatively low modulation depth, while CNTs require precise control of their diameter for generating a specific absorption spectrum .…”