Advanced Photonics Research最新文献

The photoinitiating system (PIS) is a key component of holographic materials which needs to be carefully selected and optimized to achieve efficient photopolymerization and, as a result, highly efficient holographic structures. Recently, boron dipyrromethene (BODIPY) dyes have been introduced as a new class of photosensitizers for holographic materials, including photopolymerizable glass, which is characterized by excellent environmental stability. Here, we present a study of the holographic recording capability of a photopolymerizable glass, where PIS was optimized using two approaches: (1) adding a second co-initiator, diphenyl iodonium hexafluorophosphate (DPIHFP) and (2) exploring a range of BODIPY structures, such as anthracene- and pyrene-BODIPYs. The performance of a novel pyrene-BODIPY dyad was compared with commercially available Erythrosine B, used as a reference. Remarkably, a 9-fold increase in the diffraction efficiency and refractive index modulation (RIM) was achieved by replacing Erythrosine B with pyrene-BODIPY dyads, indicating enhanced photopolymerization kinetics with BODIPY sensitization. In addition, incorporating a second co-initiator, DPIHFP, further increases the exposure sensitivity by a factor of three. These results demonstrate the high efficiency of BODIPY-based PIS formulations and underscore photopolymerizable glass as a promising platform for developing highly efficient holographic optical elements.

Lead halide perovskite nanocrystals (PNCs) are a highly promising class of materials for optoelectronic applications, due to their exceptional optical properties. Nevertheless, their poor stability has remained a major obstacle to practical implementation. This work reports highly stable lead halide PNCs of the compositions MAPbBr₃ and FAPbBr₃ (MA = methylammonium, FA = formamidinium). The nanocrystals are prepared via a facile, single-step precipitation procedure using the amino acid derivative N_α-(tert-butoxycarbonyl)-L-lysine (boc-Lys) and hexanoic acid as ligands. Films of the precipitated nanocrystals exhibit near-unity photoluminescence quantum yields and outstanding stability, maintaining their optical properties for more than 150 days (MAPbBr₃) and 490 days (FAPbBr₃) under ambient conditions, and for over 20 h under continuous blue light excitation. The excellent stability of the nanocrystals is attributed to an in situ formed encapsulating matrix, which initially consists of a complex formed between PbBr₂ and boc-Lys. Furthermore, it is demonstrated that the isolated PbBr₂/boc-Lys matrix material can be used as precursor for growing highly luminescent, stable MAPbBr₃ nanocrystals through exposure to methylammonium bromide vapors. The presented nanocrystals are excellent candidates for light-emission applications and could provide a blueprint for designing precursor materials for the growth of high-quality, stable PNCs via metal halide-amino acid complexes.

Current diagnostic tools for multidrug-resistant tuberculosis (MDR-TB) are molecular assay-based and have challenges associated with labor-intensive workflows, complex laboratory infrastructures, and limited mutation coverage. This highlights the need for alternative techniques that can be used as diagnostic tools for MDR-TB. In this study, we demonstrated the use of an surface plasmon resonance (SPR)-based biosensor chip for the detection of selected genes (InhA, KatG, and RpoB) within the MDR-TB genome using single-stranded deoxyribonucleic acids (ssDNA) targets and thiolated probes. The probes were successfully functionalized to AuNPs and confirmed using UV–vis and DLS. On SPR-based detection, the hybridization of the selected probes to complementary and non-complementary targets induced changes in the resonance angles. The hybridization of the selected probes to the targets was observed at resonance angles of 46.85, 46.77, 45.84, and 46.91° for the IS6110, InhA, KatG, and RpoB genes, respectively. In contrast, the unhybridized probe and the non-complementary targets exhibited resonance angles of 46.33, 46.05, 45.53, and 45.85° for the IS6110, InhA, KatG, and RpoB genes, respectively. The data showed that SPR-based biosensing can be refined and considered as an alternative approach to detect and differentiate between different ssDNA targets using thiolated probes as biorecognition elements for MDR-TB detection.

Current diagnostic tools for multidrug-resistant tuberculosis (MDR-TB) are molecular assay-based and have challenges associated with labor-intensive workflows, complex laboratory infrastructures, and limited mutation coverage. This highlights the need for alternative techniques that can be used as diagnostic tools for MDR-TB. In this study, we demonstrated the use of an surface plasmon resonance (SPR)-based biosensor chip for the detection of selected genes (InhA, KatG, and RpoB) within the MDR-TB genome using single-stranded deoxyribonucleic acids (ssDNA) targets and thiolated probes. The probes were successfully functionalized to AuNPs and confirmed using UV–vis and DLS. On SPR-based detection, the hybridization of the selected probes to complementary and non-complementary targets induced changes in the resonance angles. The hybridization of the selected probes to the targets was observed at resonance angles of 46.85, 46.77, 45.84, and 46.91° for the IS6110, InhA, KatG, and RpoB genes, respectively. In contrast, the unhybridized probe and the non-complementary targets exhibited resonance angles of 46.33, 46.05, 45.53, and 45.85° for the IS6110, InhA, KatG, and RpoB genes, respectively. The data showed that SPR-based biosensing can be refined and considered as an alternative approach to detect and differentiate between different ssDNA targets using thiolated probes as biorecognition elements for MDR-TB detection.

GeSn has emerged as a promising alternative in Si photonics due to its narrow and tunable bandgap. In this study, GeSn waveguide photodetectors (WGPDs) based on a lateral p–i–n homojunction architecture are demonstrated. Incorporating 10.82% Sn effectively reduces the bandgap, extending the photodetection range to 2745 nm and covering the entire short-wave infrared (SWIR) region. A lateral p–i–n homojunction diode with good optical confinement and long photon-absorbing length is developed to significantly enhance the optical responsivity. The close proximity of the direct (Γ_c) and indirect (L_c) conduction bands allows excitation of electrons from Γ_c to L_c, increasing electron lifetime. As a result, the carrier collection efficiency improves with higher bias. This momentum-space separation mechanism enables device operation at a low electric field of ≈2.5 kV cm⁻¹. These findings suggest that the fabricated GeSn WGPDs are strong candidates for full-range SWIR detection applications.

GeSn has emerged as a promising alternative in Si photonics due to its narrow and tunable bandgap. In this study, GeSn waveguide photodetectors (WGPDs) based on a lateral p–i–n homojunction architecture are demonstrated. Incorporating 10.82% Sn effectively reduces the bandgap, extending the photodetection range to 2745 nm and covering the entire short-wave infrared (SWIR) region. A lateral p–i–n homojunction diode with good optical confinement and long photon-absorbing length is developed to significantly enhance the optical responsivity. The close proximity of the direct (Γ_c) and indirect (L_c) conduction bands allows excitation of electrons from Γ_c to L_c, increasing electron lifetime. As a result, the carrier collection efficiency improves with higher bias. This momentum-space separation mechanism enables device operation at a low electric field of ≈2.5 kV cm⁻¹. These findings suggest that the fabricated GeSn WGPDs are strong candidates for full-range SWIR detection applications.

Quasi-2D metal-halide perovskite LEDs (PeLEDs) are promising for displays but remain limited by trap-mediated loss and short lifetimes, especially in the blue. Here, we report a triple-cation A-site doping strategy by co-incorporating Rb⁺ and guanidinium (GA⁺) with Cs⁺ to simultaneously improve efficiency and stability. Rb⁺ contracts the lattice and extends the radiative lifetime, whereas GA⁺ predominantly passivates surface and interfacial defects and moderates the quasi-2D phase distribution. Together they extend photoluminescence lifetimes and suppress trap-assisted nonradiative pathways, as confirmed by time-resolved photoluminescence and trap analyses. We further augment the device performance by a yttrium additive and a modified hole-injection layer. The optimized sky-blue devices achieve an external quantum efficiency of 9.0% at 492 nm and the operating lifetime (T₅₀) over 18 min at 100 cd m⁻². This synergy between A-site alloying, additive engineering, and HTL modification provides a practical route toward efficient, more stable sky-blue quasi-2D PeLEDs.

Quasi-2D metal-halide perovskite LEDs (PeLEDs) are promising for displays but remain limited by trap-mediated loss and short lifetimes, especially in the blue. Here, we report a triple-cation A-site doping strategy by co-incorporating Rb⁺ and guanidinium (GA⁺) with Cs⁺ to simultaneously improve efficiency and stability. Rb⁺ contracts the lattice and extends the radiative lifetime, whereas GA⁺ predominantly passivates surface and interfacial defects and moderates the quasi-2D phase distribution. Together they extend photoluminescence lifetimes and suppress trap-assisted nonradiative pathways, as confirmed by time-resolved photoluminescence and trap analyses. We further augment the device performance by a yttrium additive and a modified hole-injection layer. The optimized sky-blue devices achieve an external quantum efficiency of 9.0% at 492 nm and the operating lifetime (T₅₀) over 18 min at 100 cd m⁻². This synergy between A-site alloying, additive engineering, and HTL modification provides a practical route toward efficient, more stable sky-blue quasi-2D PeLEDs.

Optoelectronic properties of materials are frequently examined through spectroscopic tools based on the absorption and emission of (visible) photons. Typically, one assumes that these transient characterization processes do not cause observable change of these properties because of the low power of the employed light sources. However, for flexible conjugated polymers in a medium of low viscosity, it is decidedly unclear whether photoexcitation of electrons on the backbone of a long polymer chain has an influence on macromolecular conformations and the corresponding intermolecular interactions. Here, we provide clear experimental evidence that continuous absorption of photons progressively causes persistent changes in the spectroscopic properties of conjugated polymers, accompanied by microscopically observable changes in their spatial distribution within a low-viscosity matrix. By contrast, all these changes were completely absent in nonilluminated parts of the same sample. Quantitative spectral analysis allowed to identify the fraction of molecules that underwent such metamorphosis, which increased with the dose of photoexcitation, that is, with the number of absorbed photons. Complementary experiments revealed the reversibility of this behavior and so demonstrated the integrity of the polymers. Our results depict new pathways for tailoring properties of conjugated polymers and widening their spectrum of advanced engineering applications.

Deep learning (DL) technology has shown extensive potential for modeling radio-over-fiber (RoF) systems. Meanwhile, frequency multiplication technology serves as an effective approach to reduce the bandwidth requirements of core components in RoF links. However, the introduction of harmonic interference, nonlinear distortion, and phase noise in frequency-doubled RoF systems poses additional challenges to DL-based modeling and optimization. A DL-based frequency doubled RoF link end-to-end (E2E) modeling and optimization method is proposed. The DL model consist of three models: a signal preprocessing model for symbol mapping and signal generation, a fiber channel model for transmission link modeling in addition with a receiver model for demodulation. Numerical analysis is carried out based on 16QAM RoF signal with a bit rate of 2 Gbit/s, which indicates that the DL model is capable of modeling the frequency doubled RoF link which incorporates harmonic and nonlinear distortion effects. Moreover, geometry shaping and probabilistic shaping are performed based on E2E framework to further enhance the performance of the system. The results show that the optimized link has better bit error rate performances, indicating that our approach holds potential applications in nonlinear RoF link modeling and could valuable insights for advanced communication systems.