Nanophotonic devices offer an unprecedented ability to concentrate light into small volumes which can greatly increase nonlinear effects. However, traditional plasmonic materials suffer from low damage thresholds and are not compatible with standard semiconductor technology. Here we study the nonlinear optical properties in the novel refractory plasmonic material titanium nitride using the Z-scan method at 1550 nm and 780 nm. We compare the extracted nonlinear parameters for TiN with previous works on noble metals and note a similarly large nonlinear optical response. However, TiN films have been shown to exhibit a damage threshold up to an order of magnitude higher than gold films of a similar thickness, while also being robust, cost-efficient, bio-and CMOS-compatible. Together, these properties make TiN a promising material for metalbased nonlinear optics. Recently, TiN has been suggested as a refractory metal (melting point > 2900°C) with plasmonic properties similar to gold [19]. In addition, TiN has tunable optical properties, is chemically stable, can be grown epitaxially on magnesium oxide, c-sapphire, and silicon, and is bio-and CMOS-compatible, all in stark contrast to the noble metals [19,20]. In fact, TiN-based metasurfaces have been experimentally demonstrated to withstand temperatures and optical intensities greater than gold structures, making them potentially interesting for applications in nonlinear optics [21]. However, the inherent nonlinearities of this
For the first time thick orientation-patterned GaP (OPGaP) was repeatedly grown heteroepitaxially on OPGaAs templates as a quasi-phase matched medium for frequency conversion in the mid and longwave IR, and THz regions. The OP templates were fabricated by wafer-bonding and in a MBE-assisted polarity inversion process. Standard low-pressure hydride vapor phase epitaxy (LP-HVPE) was used for one-step growth of up to 400 µm thick device quality OPGaP with excellent domain fidelity. The presented results can be viewed as the missing link between a welldeveloped technique for preparation of OP templates, using one robust nonlinear optical material (GaAs), and the subsequent thick epitaxial growth on them of another material (GaP). The reason for these efforts is that the second material has some indisputable advantages in point of view of thermal and optical properties but the preparation of native templates encounters challenges, which makes it difficult to obtain high quality homoepitaxial growth at an affordable price. Successful heteroepitaxial growth at such a relatively high lattice mismatch (-3.6%) in a close to equilibrium growth process such as HVPE is noteworthy, especially when previously reported attempts, for example, growth of OPZnSe on OPGaAs templates at about 10 times smaller lattice mismatch (+ 0.3%) have produced only limited results. Combining the advantages of the two most promising nonlinear materials, GaAs and GaP, is a solution that will accelerate the development of high power, tunable laser sources for the IR and THz region, which are in great demand on the market.
In this work, a new phosphonium-containing cationic polyelectrolyte (PE1) has been rationally designed and developed via a facile click-chemistry type postfunctionalization, which can form complexes with highly polarizable anionic cyanines to significantly reduce the strong and random cyanine–cyanine interactions (i.e., aggregation) in the solid-state. This material design strategy enables an efficient translation of the favorable molecular properties of cyanines into macroscopic material properties. One of such complexes exhibits a very large third-order susceptibility over 10–10 esu with low nonlinear optical loss suitable for all optical signal processing.
The exchange stiffness coefficient, Aex, represents the strength of direct exchange interactions among neighboring spins. Aex is linked to most of the magnetic properties such as skyrmion formation, magnetic vortex, magnetic domain wall width, and exchange length. Hence, the quantification of Aex is essential to understanding fundamental magnetic properties, but little is known for the dynamics of Aex on a sub-picosecond timescale. We report the ultrafast dynamcis of Aex in an ordered magnetic state in Co/Pt ferromagnetic multilayer. Time-resolved magneto-optical Kerr effect and reflectivity measurements were analyzed for various pump fluences. We reveal that the significant dynamical reduction of Aex is responsible for the dramatic increase of remagnetization time for high fluences. The analysis shows that Aex dynamically varies, strongly affecting overall ultrafast demagnetization/remagnetization process. The investigation demonstrates the possibility of Aex engineering in femtosecond timescale and thereby provides a way to design ultrafast spintronic devices.
The magnetic cooling effect originates from a large change in entropy by the forced magnetization alignment, which has long been considered to be utilized as an alternative environment-friendly cooling technology compared to conventional refrigeration. However, an ultimate timescale of the magnetic cooling effect has never been studied yet. Here, we report that a giant magnetic cooling (up to 200 K) phenomenon exists in the Co/Pt nano-multilayers on a femtosecond timescale during the photoinduced demagnetization and remagnetization, where the disordered spins are more rapidly aligned, and thus magnetically cooled, by the external magnetic field via the lattice-spin interaction in the multilayer system. These findings were obtained by the extensive analysis of time-resolved magneto-optical responses with systematic variation of laser fluence as well as external field strength and direction. Ultrafast giant magnetic cooling observed in the present study can enable a new avenue to the realization of ultrafast magnetic devices.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.