arXiv subjects

Cristian Gonzalez

Publications and source records attributed to Cristian Gonzalez.

4 recordsLinked to original sources

arXiv2026

Quantum Dot Colloidosomes as Triggerable Microlasers

Quantum dot (QD) supraparticle lasers are promising platforms for microscale light sources and photonic labeling, yet their optical properties are set during assembly. Here we introduce QD colloidosomes, liquid-core/solid-shell supraparticles that combine whispering-gallery-mode optical feedback with stimulus-triggered structural collapse. Intact QD colloidosomes show cavity-defined lasing with fluence thresholds of ~2.8 mJ/cm2 and linewidths of 2.2-3.7 nm, demonstrating efficient light trapping without a solid core. We identify shell continuity as a critical determinant for whispering-gallery feedback and lasing by exploring a morphological continuum of suprastructures comprising solid supraparticles, colloidosomes, and microporous hollow shells. Intact colloidosomes support narrow cavity modes, whereas porous shells remain broadband even at high pump fluence. We show that colloidosomes can be driven to rupture and release payload through well-defined pathways, including meniscus-driven capillary failure, uniform heating, and localized near-infrared activation, thereby reconfiguring their optical response from cavity-defined lasing to broadband emission. These results establish QD colloidosomes as reconfigurable microlasers that couple optical-state switching and triggered release within a single self-assembled platform.

physics.optics↗

arXiv2026

Cavity-Mediated Radiative Energy Transfer Enables Stable, Low-Threshold Lasing in Hybrid Quantum Dot-Nanoplatelet Supraparticles

Colloidal semiconductor nanocrystals are promising building blocks for optoelectronics due to their solution processability, spectral tunability, and ability to self-assemble into complex architectures. However, their use in lasing application remains limited by high working thresholds, rapid nonradiative losses from Auger recombination, and sensitivity to environmental conditions. Here, we report hybrid microscale supraparticles composed of core/shell CdSe/ZnS quantum dots (QDs) and CdSe/CdxZn1-xS nanoplatelets (NPLs), which overcome these limitations through efficient, cavity-mediated energy funneling and coupling. Broadband absorbing QDs rapidly transfer excitation to narrow emitting NPLs, enabling stable whispering gallery mode lasing with a low threshold of 0.35 mJ/cm2. These supraparticles retain optical performance after prolonged exposure to air, water, and continuous irradiation, offering practical advantages for optoelectronic devices and advanced pigment technologies. Ultimately, our approach provides a versatile, programmable platform for optical amplification and tunable emission control within colloidal photonic architectures. Keywords

cond-mat.mtrl-sci↗

arXiv2025

Cavity Enhanced Emission from Telecom Rare-Earth System in Colloidal Host

Erbium incorporated in a ceria (CeO2) host offers strong potential as a spin qubit platform, providing a pathway toward telecom-compatible quantum memory. But erbium is a dim emitter due to its long excited state lifetime. Methods to enhance its emission rate and efficiency through nanophotonic cavity integration are therefore essential. In this work, we demonstrate cavity-enhanced emission from erbium doped CeO2. We couple colloidally synthesized erbium doped CeO2 nanocrystals to a silicon nanobeam cavity and show a 30-fold improvement in emitter brightness combined with a 2-fold lifetime enhancement. We estimate a lower bound of 12 for the Purcell factor of cavity-coupled emitters after accounting for non-radiative decay. These results pave the way towards utilizing colloidally synthesized optically addressable spin qubits emitting at telecom wavelength for quantum networking and distributed quantum computing.

physics.optics↗

arXiv2024

SoccerNet 2024 Challenges Results

The SoccerNet 2024 challenges represent the fourth annual video understanding challenges organized by the SoccerNet team. These challenges aim to advance research across multiple themes in football, including broadcast video understanding, field understanding, and player understanding. This year, the challenges encompass four vision-based tasks. (1) Ball Action Spotting, focusing on precisely localizing when and which soccer actions related to the ball occur, (2) Dense Video Captioning, focusing on describing the broadcast with natural language and anchored timestamps, (3) Multi-View Foul Recognition, a novel task focusing on analyzing multiple viewpoints of a potential foul incident to classify whether a foul occurred and assess its severity, (4) Game State Reconstruction, another novel task focusing on reconstructing the game state from broadcast videos onto a 2D top-view map of the field. Detailed information about the tasks, challenges, and leaderboards can be found at https://www.soccer-net.org, with baselines and development kits available at https://github.com/SoccerNet.

cs.CV↗