Advanced Photonics Research
ISSN / EISSN : 2699-9293 / 2699-9293
Published by: Wiley-Blackwell (10.1002)
Total articles ≅ 262
Latest articles in this journal
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100198
Metal halide perovskites (MHPs) are attracting ever-growing interest across diverse optoelectronic subdisciplines. Yet, the physical mechanism underlying photoexcitation and subsequent photocarrier dynamics remains poorly understood, due to the apparent spectroscopic diversities observed for any certain MHP. Here, diverse spectroscopic characteristics, including static spectral line-shapes and time-resolved photoluminescence (TRPL) traces shown by polycrystalline versus single-crystalline CH3NH3PbBr3 perovskites, are restudied. Key photophysical merits, including exciton binding energy (EB), Sommerfeld factor (ξ), and Urbach energy (EU) that account for the diversities, are discussed within the established framework of semiconductor optics. The value of ξ, which increases with EB, determines how much the interband absorption is enhanced beyond that expected for free carriers. The intrinsic band-edge luminescence is identified, with its asymmetric spectral line-shape linked to EU via the van Roosbroeck–Shockley relation. Excited phase evolution, accompanied by rapid electron–hole (e–h) pairs dissociation and subsequent occurrence of e–h plasma, is indicated by the two-stage TRPL traces that are only observable for high-quality single crystals. With all the spectroscopic analysis and interpretations rooted in the established semiconductor optical theorems, the mechanistic merits revealed in this study are informative for plausible identification between the interband and excitonic photophysical processes of MHPs.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100183
Van der Waals heterostructures (vdWHs) based on graphene/III−V semiconductors have attracted considerable interest. Although diverse proof-of-concepts are demonstrated, it is a challenge to make a tunable array device using such vdWHs that severely limit its practical applications. Herein, a controllable and reliable two-step femtosecond (fs) and nanosecond (ns) pulsed laser postprocessing method to enhance the material quality is described–especially the nonlinear optical (NLO) characteristics of such vdWHs, the significantly improved light absorption capability, and the obviously reduced saturable fluence (SF) are simultaneously obtained compared with the as-grown device, allowing to construct a stable and high-performance ultrafast fiber laser. In addition, benefiting from the unique selective-area annealing nature of laser postprocessing, a saturable absorber (SA) plane array device by the same original vdWHs but under various fs and ns laser annealing treatments is realized, exhibiting large tuning ranges of modulation depth (from 1.6 to 11.2%) and SF (from 13.7 to 1.1 MW cm−2), paving a new way to fabricate an array device using vdWHs.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100130
Plasmon resonances (PRs) in metallic nanostructures have been extensively studied, whereas reports on PR in silicon nanowires (Si NWs) are very few, partial, and they refer to structures larger than 100 nm. Discrete resonances in Si NWs with core sizes as small as 30 nm at high resolution are observed. They are attributed to plasmonic resonances identifying two groups, the traveling waves, exhibiting discrete modes along the NW length for several orders of harmonics, and the localized waves, generated by transverse oscillations along the NW diameter, observing them to the best of our knowledge for the first time in silicon NWs (SiNWs) of every size. The experimental findings are coupled to modeling, confirming the data and adding further insights into the Si NW's embedding medium role. A plasmon-induced resonant cavity in Si NWs opens markets in material processing, photodetectors, and novel plasmon-based nano-optics, thanks to the intense optical energy delivery below the diffraction limit and the addition of the exceptional integration capacity of silicon.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100189
Colloidal micromotors are important candidates for a wide spectrum of applications, ranging from medicine to environmental remediation. Thus far, the propulsion force determination has been obtained from the colloidal motor motion speed and surrounding viscosity via the Stokes drag. Herein, a precise force measurement method and detailed analysis of the fundamental propulsion mechanisms of colloidal Janus micromotors propelled by thermophoretic and steam bubble force vectors, revealing findings uninvestigated to date, are presented. Optical tweezers provide fast and high-precision force measurements in all three orthogonal dimensions simultaneously. Colloidal Janus micromotors are compared with isotropic hot Brownian reference microparticles, which have no defined force vector that propels them perpendicular to the direction of the laser beam. Janus micromotors display a defined laser power intensity-dependent thermophoretic propulsion, as well as bubble force-based propulsion, after surpassing the threshold value for the water boiling. The steam bubble propulsion force vector and the thermophorethic force vectors sum up for the Janus micromotor propulsion direction. On the contrary, the bubble force counteracts photophoretic force in propagation direction of light. Moreover, the thermal-based reduction of viscosity around the Janus colloidal motor contributes significantly to its speed and guidance abilities.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100184
Broadband and ultrafast response of plasmonic nanoparticles offer a significant advantage in optical modulation and allow ultrashort pulse generation from visible to mid-infrared (MIR) region. However, many of the materials exhibit limited saturable absorption bandwidth in MIR spectral region, which limits the MIR pulses generation and the relative applications. Herein, it is shown that solution-processed silver nanowires (AgNWs) exhibit an ultrabroadband localized surface plasmon resonance (LSPR) from 0.3 to over 25 μm, which contributes to wideband nonlinear optical response in the whole MIR region. Using those AgNWs as saturable absorbers (SA), all-optical modulation in near infrared and MIR region is demonstrated. Mode-locked lasers are realized at 1, 1.5, and 2 μm bands with minimal pulse duration down to a few hundreds of femtoseconds, and a Q-switched laser at 3 μm band is achieved. The results show that AgNWs SA has the potential for constructing pulsed lasers in the MIR or even longer wavelength region.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100165
Amid the search for efficient terahertz transmission and gas sensing, all-polymer terahertz waveguides attract significant interest due to their compactness and capability for providing environmentally robust systems. The high loss within metals and dielectrics in the terahertz range makes it challenging to build a low loss, mechanically stable, and broadband terahertz waveguides. In this context, hollow waveguides made of Zeonex are promising for attaining low transmission loss in the terahertz range. Herein, a microstructured hollow hexagonal-core fiber (HCF) is investigated, which exhibits low loss, near-zero dispersion, wide operating bandwidth, and is suitable as a gas sensor. Notably, HCF fabrication is carried out by exploiting an efficient single-step extrusion method—by a standard filament extruder and a puller; hence the production cost is low compared with conventional extrusion methods. This introduces a novel way of fabricating complex and low-loss terahertz fibers. The experiments demonstrate that an HCF can achieve remarkably low attenuation and near-zero flattened dispersion as compared with any other terahertz fibers. The resulting HCFs are easy to handle and have high thermal and chemical stability. These results bring significant advancements for terahertz fiber fabrication, low-loss ultrafast short-distance terahertz transmission, and sensing in the terahertz spectral domain.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100158
Conventional metamaterial design mainly relies on manual trial-and-error design and optimization to achieve target electromagnetic responses. When faced with high-degree-of-freedom application design, it is impossible to achieve an efficient overall design of massive metamaterial structural units. Herein, a new approach for using ensemble learning for objective-driven easy-to-process metamaterial design. From the perspective of data and learners, reduce the complexity of data preprocessing and achieve accurate closed-loop design by improving the overall performance of the learning model. The proposed framework overcomes some core problems, which have limited the previous design solutions based on a single model/network: adaptive design of different metamaterial objects, input/output vector-dimensional mismatch, precise prediction of amplitude value at the resonance frequency, lower data acquisition cost, and difficult to process. In the future, researchers can use the proposed method, integrating cutting-edge machine learning models and algorithms, to design a variety of metamaterial devices.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100138
Herein, a high-performance single-crystal diamond (SCD) detector (4.5 × 4.5 ×0.3 mm3) to achieve accurate pulse shape discrimination, which is critical for source tracking in harsh and complex radiation conditions, is demonstrated. Enabled by a deep learning algorithm based on self-organizing map (SOM) neural networks, and using the transient current technique (TCT) for sampling the detector's response to γ, α, and neutron radiation fields, the SCD detector achieves high recognition accuracy of 97.51%. The SCD detector exhibits a low leakage current of 0.75 pA mm−2 under an electric field of 0.51 V μm−1, and its response to 238Pu α-rays shows that the charge collection efficiency for electrons and holes is as high as 99.2 and 98.8% respectively, with an energy resolution as low as 1.42%. The results indicate that the high-performance SCD detector assisted by the machine learning algorithm can effectively distinguish α-particles and γ-rays with a potential application in separating the neutron and γ events as well.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100176
Among layered and 2D semiconductors, there are many with substantial optical anisotropy within individual layers, including group-IV monochalcogenides MX (M = Ge or Sn and X = S or Se) and black phosphorous (bP). Recent work has suggested that the in-plane crystal orientation in such materials can be switched (e.g., rotated through 90°) through an ultrafast, displacive (i.e., nondiffusive), nonthermal, and lower-power mechanism by strong electric fields, due to in-plane dielectric anisotropy. In theory, this represents a new mechanism for light-controlling-light in photonic integrated circuits (PICs). Herein, numerical device modeling is used to study device concepts based on switching the crystal orientation of SnSe and bP in PICs. Ring resonators and 1 × 2 switches with resonant conditions that change with the in-plane crystal orientations SnSe and bP are simulated. The results are broadly applicable to 2D materials with ferroelectric and ferroelastic crystal structures including SnO, GeS, and GeSe.
Advanced Photonics Research; https://doi.org/10.1002/adpr.202100177
Recent progress on perovskite lasers has shown the large potential for such materials to become a basis for commercially available microlasers in the near feature. Herein, distributed feedback (DFB) lasers based on vacuum-processed CsPbBr 3 are investigated. The expansion of the DFB structure from 1D to 2D suppresses parasitic amplified spontaneous emission (ASE), resulting in the multiple-time-enhanced lasing output. Further, the photoluminescence and lasing behavior of 1D and 2D DFB structures are explored through the k-space imaging analysis.