Abstract
Abstract Air-stable broadband saturable absorbers (SAs) exhibit a promising application potential, and their preparations are also full of challenges. Palladium selenide (PdSe2), as a novel two-dimensional (2D) layered material, exhibits competitive optical properties including wide tunable bandgap, unique pentagonal atomic structure, excellent air stability, and so on, which are significant in designing air-stable broadband SAs. In our work, theoretical calculation of the electronic band structures and bandgap characteristics of PdSe2 are studied first. Additionally, PdSe2 nanosheets are synthesized and used for designing broadband SAs. Based on the PdSe2 SA, ultrafast mode-locked operations in 1- and 1.5-μm spectral regions are generated successfully. For the mode-locked Er-doped operations, the central wavelength, pulse width, and pulse repetition rate are 1561.77 nm, 323.7 fs, and 20.37 MHz, respectively. Meanwhile, in all normal dispersion regions, mode-locked Yb-doped fiber laser with 767.7-ps pulse width and 15.6-mW maximum average output power is also generated successfully. Our results fully reveal the capacity of PdSe2 as a broadband SA and provide new opportunities for designing air-stable broadband ultra-fast photonic devices.
Highlights
The emergency of two-dimensional (2D) layered materials provided exciting opportunities for the development of novel opto-electric, bio-medical, and energy devices [1,2,3,4,5,6,7,8,9,10,11,12,13]
The absorption performance of the PdSe2-polyvinyl alcohol (PVA) saturable absorbers (SAs) was tested within an Er-doped fiber laser for the first time
A commonly used ring laser cavity consisting of a 980/1550 wavelength division multiplexer (WDM), a 0.23-m-long high doping concentration Er-doped fiber (EDF; Liekki, Er-110, 4/125), a polarization-independent isolator (PI-ISO), two polarization controllers (PCs), a 20/80 output coupler (OC), and the prepared PdSe2-PVA SA is demonstrated
Summary
The emergency of two-dimensional (2D) layered materials provided exciting opportunities for the development of novel opto-electric, bio-medical, and energy devices [1,2,3,4,5,6,7,8,9,10,11,12,13]. Exploring air-stable materials with wide tunable bandgap value is of great significance in promoting the practical optical device applications of 2D materials. The calculated results prove that PdSe2 exhibits a wide tunable indirect bandgap of 0–1.3 eV, which is suitable for designing broadband ultra-fast optical devices. The excellent wideband absorption performance of PdSe2 presents that PdSe2 exhibits great potential and capacity in designing wide absorption band ultra-fast optical devices. The calculated electronic band structures of bulk and single-layer PdSe2 are provided in Figure 2A and B, respectively. The bandgap values for 20 layers and bulk PdSe2 are 0 and −0.01 eV, respectively, which proves that bulk PdSe2exhibits no bandgap Such a large tunable bandgap is of great significance for designing broadband opto-electronic devices
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