Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 0707.1434

Spectroscopy, upconversion dynamics, and applications of Er3+-doped low-phonon materials

Angel J. Garcia-Adeva
View original source ↗Read source document ↗Export metadata ↓

Abstract

In this work I summarize some of the recent work carried out by our group on the upconversion dynamics of Er3+-doped potassium lead halide crystals, which possess very small phonons and present very efficient blue and green upconversion. Furthermore, a non-conventional application of these RE-doped low-phonon materials in optical refrigeration of luminescent solids is also discussed, paying especial attention to new pathways for optical cooling that include infrared-to-visible upconversion. Finally, I conclude with some hints of what I think it is the next step into improving the luminescence efficiency of solids: the use of RE-doped nanoscale photonic heterostructures for controlling the density of photonic states.

Explore related subjects

cond-mat.othercond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Angel J. Garcia-Adeva. 2007-07-10. Spectroscopy, upconversion dynamics, and applications of Er3+-doped low-phonon materials. https://arxiv.org/abs/0707.1434

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Ultrafast laser-stimulated field emission from a metal: a non-equilibrium Green's functions approach

Ultrafast laser-assisted field emission from metallic nanotips is a promising route for generating coherent electron pulses. However, existing theoretical models often neglect many-body strong correlation effects in the emitter's electronic structure and its response to the optical field. In this work, we propose a theoretical framework based on the non-equilibrium Green's function formalism to simulate the out-of-equilibrium electron dynamics across a strongly driven matter-vacuum interface, in a one-dimensional model. Treating the tip-vacuum coupling perturbatively, we find that the interplay between strong-field emission and multi-photon emission regimes can be described in terms of a filtering of the emitter's local density of occupied states through field-dressed vacuum propagators. By including electron-electron interactions via the second-Born approximation, we show that correlation-induced modifications in the electronic structure are directly transferred to the far-field spectrum. Finally, by self-consistently solving the Dyson equation at the interface, we uncover a dynamic back-action regime driven by the optical field, characterized by a periodic polarization of the emitter, which reshapes the far-field spectrum. This shows that the non-equilibrium Green's functions approach provides a versatile framework for exploring and analyzing field emission of correlated electrons.

cond-mat.other↗
arXiv2026

Revealing New Leakage Paths in GAAFETs using Predictive First-Principles Simulations

Gate-All-Around Field-Effect Transistors (GAAFETs) are emerging as successors to Fin Field-Effect Transistors (FinFETs) and are central to continued scaling at advanced semiconductor nodes. Despite their improved electrostatic control, recent measurements show that the drain current in GAAFETs deviates strongly from thermionic behavior at negative gate voltages, increasing as the gate voltage becomes more negative. This leakage has been attributed to direct gate-drain tunneling through the high-$k$ dielectric, enhanced by drain-induced dielectric barrier lowering (DIDBL). Here, we use predictive, charge-self-consistent Non-Equilibrium Green Function (NEGF) simulations based on the Contact Block Reduction (CBR) method to spatially resolve this leakage pathway in GAAFETs. Unlike approaches based primarily on phenomenological leakage models, our first-principles, multi-terminal quantum-transport framework treats the source, drain, and gate as current-carrying quantum-mechanical contacts and resolves the local current density throughout the device. The spatially resolved current density shows that gate-injected carriers tunnel through the high-$k$ dielectric preferentially near the drain side of the gate, where the dielectric barrier is most strongly lowered by the drain bias, and are collected by the drain. This provides a direct real-space picture of the DIDBL-driven gate-drain leakage mechanism.

cond-mat.other↗
arXiv2026

Integer-Graded Reciprocal Skin Effect from Internal Rotation

A prominent class of reciprocal non-Hermitian skin effects has a $\Z_{2}$ topological classification, characterized by a parity invariant protected by reciprocity. We show that conserved internal rotation refines this classification into an unbounded integer-graded hierarchy. Every angular momentum channel is an exactly solvable asymmetric chain with its own integer point-gap winding, while conjugate channels accumulate at opposite edges so that reciprocity is preserved globally. For conserved channels, the classification contains one integer per conjugate pair, with the number of independent integers determined by the internal multiplet. Half-integer spin realizes the symplectic class AII$^{\dagger}$, whose $\Z_{2}$ index is recovered as the parity of the grading. Conjugate-channel mixing destroys the grading and leaves a critical, scale-free skin effect. A cyclic three-site lattice and a passive array of lossy resonators provide minimal realizations.

cond-mat.other↗