Advanced Photonics Research最新文献

Incoherence of traditional thermal emission, such as blackbody radiation with broad bandwidth and omnidirectional nature, fundamentally restricts their practical applicability. Nanophotonic structures—particularly those engineered with subwavelength scale features—exhibit thermal radiation properties that markedly diverge from conventional emitters, enabling precise spectral and directional modulation of thermal emission. Herein, recent developments and challenges in the coherence control of thermal radiation with nanophotonics platforms are reviewed. First, the fundamental properties of thermal radiation and approaches for thermal radiation calculation are introduced. Also, recent developments of coherence control are presented, which are divided into three parts, including temporal coherence, spatial coherence, and polarization state of thermal radiation. As coherence control holds great potential for various infrared applications, the representative applications, such as infrared sensing, radiative cooling, thermal camouflage, and imaging, are subsequently introduced. Finally, a conclusion is made and the future developments of coherence control are prospected. By synthesizing current researches, this work highlights the transformative potential of coherent thermal radiation control and its impact on next-generation technologies, offering new perspectives in the areas of infrared thermal emission.

Two-step, two-frequency (TSTF) upconversion in rare-earth-ion (REI) doped solids is a proven strategy for achieving 3D volumetric displays, with potential applications in defence, healthcare, education, manufacturing, and entertainment. Early studies have primarily focused on REI-doped fluoride glasses or single crystals, which efficiently support TSTF upconversion due to their low-phonon energy. However, these materials are challenging to produce at the size and quality required for commercial applications. This study explores tellurite and germanate glasses as scalable, low-phonon-energy alternatives by benchmarking their TSTF upconversion performance against fluoride glass for Er³⁺ green fluorescence. Tellurite and germanate glasses exhibit dimmer green upconversion under continuous-wave excitation, while tellurite glass unexpectedly outperforms fluoride glass when both lasers are pulsed with properly adjusted modulation parameters. Rate equation-based simulations are used to explain these findings. In particular, tellurite glass exhibits brighter emission than fluoride glass under synchronized dual-pulsed excitation due to its much higher ground- and excited-state absorption cross sections and radiative decay rate, which compensate for its shorter ⁴S_3/2 lifetime. Green voxel generation is demonstrated in a large ≈4 × 4 × 4 cm³ Er³⁺-doped tellurite glass cube with high optical quality. These results open new directions for REI-doped glass development and laser design for TSTF upconversion-based 3D volumetric displays.

Persistent phosphors with high charge storage capacity are promising for a wide range of applications, mostly demonstrated at room temperature. Designing such long-persistent phosphor (LPP) applicable at higher temperature is largely unexplored and challenging. To prevent spontaneous charge release and ensure long-term data retention, high-temperature LPPs must feature multilevel traps with sufficient activation energies. In this report, LaAlO₃:Eu³⁺ (LAO:E) phosphor is investigated with multiple traps and four integrated luminescent emissions: down-conversion photoluminescence and radioluminescence, thermally stimulated luminescence, persistent luminescence (PersL), and optically stimulated luminescence (OSL). Unlike earlier optical storage phosphors, our LAO:E phosphor possesses charge carriers that are released from these traps, ranging from shallow trap 1 to deep trap 4, across various temperatures. The potential for the long-term storage of charge carriers at both room and elevated temperatures is also examined. Supported by experimental data and density functional theory calculations, we establish a correlation between the various traps and the desired PersL and OSL properties of the LAO:E phosphor. Additionally, a comprehensive trapping–detrapping mechanism for charge carriers is developed. The studies here are expected to pave the way for designing advanced multimode phosphors for a wide range of applications at high temperatures.

Interferometry has long been used to measure the phase of light signals. Combined with a heterodyne detection scheme, it allows to simultaneously record amplitude and phase variations. In this work, these well-known techniques are exploited to evaluate the nonlinear phase induced by the optical Kerr effect during the propagation of a laser pulse in a nonlinear medium. It is shown that the nonlinear index can easily be retrieved when the accumulated phase remains small, but counter-intuitive results can be observed at higher powers. In particular, the combination of pulsed excitation and Kerr nonlinearity results in nonlinear variations of the amplitude of the interference pattern, whose shape depends on the pulse profile and the dispersion of the propagation medium.

For developing effective reconfigurable photonic devices, low-loss phase change materials, such as Sb₂S₃, can be a good choice. Sb₂S₃-tunable directional couplers (DCs) have the lowest insertion loss in both amorphous and crystalline states. However, they suffer from a large coupling length issue, which can be overcome by combining with hybrid plasmonic waveguides (HPWGs). Herein, a Sb₂S₃-assisted HPWG-based reconfigurable, nonvolatile 1 × 2 switch that has been designed using an asymmetric DC is proposed. The proposed switch has dual-polarization functionality (operates in both transverse electric and TM modes) indicating its broader applicability and flexibility in integrated photonic systems where polarization diversity is often required. The optical characteristics and coupling behavior with phase transitions have been numerically examined. With a compact coupling length of 46 μm, the proposed 1 × 2 switch achieves a low insertion loss of ≈0.5 dB and a small crosstalk of <−10 dB over a bandwidth of 70 nm (1510–1580 nm).

Lasers operating in the visible and 3–20 μm mid-infrared (MIR) spectral ranges have become indispensable tools with broad and significant applications in fields such as display technology, biomedicine, laser-guide-star systems, and nonlinear optics. To meet the growing demand for high-performance visible and MIR lasers, nonlinear frequency conversion of fiber lasers has emerged as a promising approach, offering flexible wavelength tunability, high conversion efficiency, and high output power. This review highlights recent advances in the χ⁽²⁾-based nonlinear frequency conversion of fiber lasers in both visible and MIR wavelength regions. First, the progress in χ⁽²⁾-based frequency conversion of conventional fiber lasers, including frequency doubling, sum-frequency generation, difference frequency generation, and optical parametric oscillation, is reviewed. Additionally, the characteristics and performance of various novel fiber lasers in nonlinear frequency conversion applications, including random fiber lasers, incoherent and spectrum-tailorable superfluorescent fiber sources, and ultrafast fiber lasers, are presented. Finally, the prospects and challenges associated with the frequency conversion of fiber lasers are discussed, providing insights into future directions and potential solutions.

Modeling and understanding the nonlinear pulse evolution in optical systems is crucial for developing modern photonic technologies. The pulse evolution often involves a complex interplay of various effects, and modeling its dynamics heavily relies on numerical simulations. Supercontinuum generation, a highly nonlinear phenomenon involving the propagation of ultrashort pulses through optical fibers, is one example of such a nonlinear dynamical problem. The idea of modeling both forward and inverse processes using a transformer-based encoder–decoder approach is put forth. To the best of the knowledge, this might be the first work to apply this framework to the task, highlighting its effectiveness in capturing complex dynamics. While the primary focus is on the transformer-based encoder–decoder model, a variety of other network architectures is also explored to evaluate model accuracy and to highlight their ability to predict complex nonlinear dynamics at a fraction of the computational cost of traditional numerical methods. This article demonstrates the potential of transformer-based approaches for modeling nonlinear optical systems and their ability to generalize to other physical systems.

The transition to multichip and accelerator-rich computing architectures has exposed the limitations of conventional wired interconnects, including bandwidth constraints, latency, and power inefficiencies. While wireless interconnects provide a scalable alternative, existing transceiver technologies often lack the interference resilience required for efficient multichip communication. To address these challenges, a terahertz (THz) modular phased array (MPA) transmitter and a 2D semiconductor quantum well (2DSQW)-based nanoreceiver are introduced, enabling noise-resilient signal demodulation without bulky processing hardware. The dual-carrier MPA model enhances beam focusing precision while suppressing grating lobes and mitigating polarization mismatch with the receiver. The receiver response is characterized using Floquet engineering, leveraging the quantum behavior of charge carriers in time-periodic radiation fields to achieve accurate polarization-dependent response tuning. The 2DSQW-based receiver's unique geometric design facilitates spatial modulation, ensuring robust noise suppression and interference detection. This architecture is particularly well-suited for vertical communication in multichip quantum processors, where high wiring density and thermal constraints hinder scalability. By operating the MPA transmitter at elevated temperatures while maintaining the receiver at lower temperatures, effective thermal isolation is achieved. The proposed THz dual-carrier MPA and 2DSQW-based receiver provide a high-bandwidth, low-power solution for scalable wireless multichip communication in both classical and quantum computing systems.

Type-II quantum rings (QRs) exhibit unique physics with great potential for future technologies. In this work, the magneto-optical properties and carrier dynamics of single- and ten-layer stacked GaSb/GaAs QR ensembles fabricated by molecular beam epitaxy are investigated. Activation energies extracted in both single- and ten-layer structures with temperature-dependent photoluminescence (PL), establish recombination dynamics closely linked to the growth method of the nanostructures. Clear optical absorption characteristics are also determined with PL-excitation experiments. In addition, transient temperature-dependent PL reveals distinct recombination pathways through nontrivial carrier decay behavior. With increasing excitation power density, a strong blue shift in peak position energies is observed due to evolving carrier kinetics across low and high excitation regimes. Finally, optical Aharonov–Bohm oscillations are demonstrated for the first time in type-II QRs. The data presented here are expected to advance the optimization of growth and physical properties of GaSb/GaAs QRs.

Coffee is one of the most popular beverages, characterized by a complex composition and individual flavor profiles, strongly affected by extraction methods. A continuous and scalable cold extraction method based on irradiation of coffee particle dispersions (<200 μm) with a picosecond-pulsed laser is exploited, analyzing the influence of laser fluence (20–690 mJ cm⁻²) and pulse number (1–10) on the extract composition. The results highlight the generation of a unique volatile aroma profile at low fluence (35 mJ cm⁻²) and a reduced acidity in the liquid phase, which is neither correlated with a global temperature increase nor with changes in the specific surface area. This unique aroma profile is attributed to pulsed laser diffusion enhancement in liquids, resulting in localized heating and substance-specific alteration of the extraction kinetics, with energy consumption three times lower than classical hot coffee extraction and the potential for technical scale processing.