One‐dimensional (1D) ferroelectric nanostructures, such as nanowires, nanorods, nanotubes, nanobelts, and nanofibers, have been studied with increasing intensity in recent years. Because of their excellent ferroelectric, ferroelastic, pyroelectric, piezoelectric, inverse piezoelectric, ferroelectric‐photovoltaic (FE‐PV), and other unique physical properties, 1D ferroelectric nanostructures have been widely used in energy‐harvesting devices, nonvolatile random access memory applications, nanoelectromechanical systems, advanced sensors, FE‐PV devices, and photocatalysis mechanisms. This review summarizes the current state of 1D ferroelectric nanostructures and provides an overview of the synthesis methods, properties, and practical applications of 1D nanostructures. Finally, the prospects for future investigations are outlined.
Kang et al. summarized the mechanism of formation of anti-site defects in LiNbO3/LiTaO3 crystals and the measures for growth of anti-site defect free LiNbO3/LiTaO3 crystals to give the readers an overview in this field.
We demonstrate up-conversion single-photon detectors based on integrated periodically poled lithium niobate waveguides, which incorporate two mode filters and a directional coupler. The two mode filters are optimized for the fiber-waveguide coupling efficiencies for 1550 nm and 1950 nm respectively while the directional coupler plays the role of wavelength combiner, making the overall system portable and low-cost. The two wavelengths pump each other in our detection system. We achieve detection efficiencies of 28% for 1550 nm and 27% for 1950 nm, respectively. This scheme provides an efficient integrated single-photon detection method for any two well-separated spectral bands in the whole low-loss range of lithium niobate waveguides.
We demonstrate a compact all-fiber polarization-independent up-conversion single-photon detector based on integrated reverse proton exchanged periodically poled lithium niobate waveguides. The horizontally and vertically polarized components of randomly polarized signals are separated with a fiber-coupled polarization beam splitter, launched into two orthogonally polarized polarization maintaining fibers and fetched into two adjacent independent waveguides on the same device. The up-converted outputs from both waveguide channels are then combined with a multi-mode fiber combiner and detected by a silicon detector. With this configuration, the polarization-independent single-photon counting at 1.55 m is achieved with a system detection efficiency of 29.3%, a dark count rate of 1600 counts per second, and a polarization dependent loss of 0.1dB. This compact all-fiber system is robust and has great application potential in practical quantum key distribution systems.Keywords:polarization-independent; single-photon detector; up-conversion; periodically poled lithium niobate waveguide.
Ytterbium
and erbium codoped crystals have attracted considerable
interest in the application of eye-safe laser, upconversion laser,
and low-loss optical communication. Despite the lithium niobate (LiNbO3, LN) single crystal has been accepted as an ideal crystal
matrix for Yb3+ and Er3+ ions possessing significant
application potential in self-upconversion laser, the Yb and Er codoped
near-stoichiometric LN (NSLN) crystal has rarely been studied. This
is due to the difficulty of the NSLN crystal growth compared with
that of the congruent LN (CLN). In this paper, an Yb, Er codoped near-stoichiometric
LN (Yb, Er:NSLN) crystal was grown by the Czochrolski method for the
first time. Spectra studies showed the constrained peak splitting
at 378, 526, and 650 nm of the Yb, Er:NSLN crystal compared with Yb,
Er:CLN crystal. It was attributed to the low concentration of intrinsic
defects which constrained the Stark-split of the three energy levels
of 4G11/2, 2H11/2, and 4F9/2 energy states. Some spectral changes are verified
induced by the stoichiometric composition in the polarized emission
spectra. The Yb, Er:NSLN crystal has high potential in upconversion
laser application.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.