Abstract Stimuli-responsive organic-inorganic metal halides hold great promise for emerging information-related applications. In this work, replacing the free halide ion Cl− with Br− in C5H11N3(MnCl3·H2O)X (where C5H11N3 2+ represents histamine cation, X represents free halide ions) converts the non-responsive hybrid C5H11N3(MnCl3·H2O)Cl into a stimuli-responsive C5H11N3(MnCl3·H2O)Br. The latter exhibits reversible photoluminescence color switching between red and green upon thermal or water exposure. Extensive experimental and theoretical analyses reveal that the responsive property primarily stems from weakened hydrogen bonding surrounding H2O molecules after Br− substitution, which facilitates the initial escape of H2O molecules under heating. Subsequent structural reorganization and coordination transformation then induce the change in photoluminescence. Furthermore, the fabricated halide/polymer luminescent films are demonstrated to be highly applicable in multiple scenarios, such as planar temperature sensing, thermal stamping, and encryption/decryption. This study highlights the crucial yet often overlooked role of free halide ions in metal halides and offers new insights into their structure–property relationships.
Hydrogen cyanide (HCN) is a toxic industrial chemical, necessitating low-level detection capabilities for safety and environmental monitoring. This study introduces a novel approach for detecting hydrogen cyanide (HCN) using a clamp-type custom quartz tuning fork (QTF) integrated with a dual-tube acoustic micro-resonator (AmR) for enhanced photoacoustic gas sensing. The design and optimization of the AmR geometry were guided by theoretical simulation and experimental validation, resulting in a robust on-beam QEPAS (Quartz-Enhanced Photoacoustic Spectroscopy) configuration. To boost the QEPAS sensitivity, an Erbium-Doped Fiber Amplifier (EDFA) was incorporated, amplifying the laser power by approximately 286 times. Additionally, a transformer-based U-shaped neural network, a machine learning filter, was employed to refine the photoacoustic signal and reduce background noise effectively. This combination yielded a significantly low detection limit for HCN at 0.89 parts per billion (ppb) with a rapid response time of 1 second, marking a substantial advancement in optical gas sensing technologies. Key modifications to the QTF and innovative use of AmR lengths were validated under various experimental conditions, affirming the system's capabilities for real-time, high-sensitivity environmental monitoring and industrial safety applications. This work not only demonstrates significant enhancements in QEPAS but also highlights the potential for further technological advancements in portable gas detection systems.
Developing the empirical method based on observation and experiment, Alhazen is considered the greatest Muslim physicist and the most significant figure in the history of optics between antiquity and the seventeenth century. Inventing a camera obscura, Alhazen rebuilt our conception of eyesight. His theory of vision was enormously prominent and much of our understanding of optics and light is based upon his groundbreaking discoveries. He began his criticism of emission by describing what happens when people are exposed to bright lights. No matter what the light source, the effect of bright lights was always the same. What this indicates to Alhazen is that light entering into the eye from an external source had some serious function in eyesight. Respecting observation, experiment and empirical method, Suhrawardi, the father of Illumination School, argues all theories of vision and rejects them just by mere reasoning. Suhrawardi validates his own Illuminationist method by scientists’ empirical method. So, I will argue, he is not to deny empirical aspect of Alhazen’s theory of vision. In an allegory, I will use the camera, representing the whole process of a human vision, while I use “beyond camera” for the embodiment that allows for the unfolding of a human soul’s position in the process of vision. What Alhazen is speaking of, we might call the process within the camera; while what Suhrawardi is speaking of, we could name the process behind the camera.
Dilfuza Begmatova, Husan Eshkuvatov, Nuraddin Abdullayev
et al.
In this article, we used modern technologies to teach the topic of nanomaterials and nanotechnologies. One of the main tasks of the development of modern nanotechnologies and nanomaterials is one of the main tasks of the development of nanoscale solid, liquid and gas phase structures and systems.
We obtain explicit analytic expressions for the Ince-Gaussian (IG) beams for several first indices p = 3, 4, 5, 6. Earlier, explicit expressions have been derived for amplitudes of the IG beams with p = 0, 1, 2 and without regard for the ellipticity parameter. Here, we give expressions for the amplitudes of 24 IG beams written as superpositions of the Laguerre-Gaussian (LG) or Hermite-Gaussian (HG) beams, with the superposition coefficients explicitly depending on the ellipticity parameter. Simultaneously expressing the IG modes both via the LG and HG modes allows easily obtaining the IG modes in the extreme cases when the ellipticity parameter is zero or infinite. Explicit dependence of the obtained expressions for the IG modes on the ellipticity allows the intensity pattern at the beam cross-section to be varied by continuously varying the parameter value. For the first time, intensity distributions are obtained for the IG beams with negative ellipticity parameter.
Epitaxially grown quantum dot (QD) lasers in narrow pockets on patterned silicon photonics wafers present a key step toward full monolithic integration of on‐chip light sources. However, InAs QD lasers grown in deep and narrow pockets demonstrate limited performance and reliability compared to planar‐grown counterparts. Herein, InAs QD lasers are grown in patterned SiO2 pockets atop planar thermal cyclic annealed GaAs on (001) Si substrate with reduced threading dislocation density, enabling detailed study of how pocket geometry impacts device performance. Fabry–Pérot lasers with cleaved facets exhibit strong variation in performance based on the dimensions of the pocket, wherein thermal and optical metrics improve with increasing pocket width. Devices lase up to a maximum stage temperature of 115 °C with an extrapolated lifetime of 2.2 years at 80 °C for material grown in 50 μm by 3900 μm pockets. This study addresses, the ongoing challenge of optimizing pocket‐grown devices to planar equivalent performance.
Diabetic retinopathy (DR) is one of the major causes of visual impairment in adults with diabetes. Optical coherence tomography angiography (OCTA) is nowadays widely used as the golden criterion for diagnosing DR. Recently, wide-field OCTA (WF-OCTA) provided more abundant information including that of the peripheral retinal degenerative changes and it can contribute in accurately diagnosing DR. The need for an automatic DR diagnostic system based on WF-OCTA pictures attracts more and more attention due to the large diabetic population and the prevalence of retinopathy cases. In this study, automatic diagnosis of DR using vision transformer was performed using WF-OCTA images (12[Formula: see text]mm × 12[Formula: see text]mm single-scan) centered on the fovea as the dataset. WF-OCTA images were automatically classified into four classes: No DR, mild nonproliferative diabetic retinopathy (NPDR), moderate to severe NPDR, and proliferative diabetic retinopathy (PDR). The proposed method for detecting DR on the test set achieves accuracy of 99.55%, sensitivity of 99.49%, and specificity of 99.57%. The accuracy of the method for DR staging reaches up to 99.20%, which has been proven to be higher than that attained by classical convolutional neural network models. Results show that the automatic diagnosis of DR based on vision transformer and WF-OCTA pictures is more effective for detecting and staging DR.
Pedram Hosseini, Prachi Agrawal, Alireza Tabatabaei Mashayekh
et al.
We present a silicon-nitride-based optical phased array with built-in focusing and steering capability, that operates at 522 nm and is aimed at complementing a micro-electrode array for joint electrical and optical probing of retinal tissue. It achieves subcellular resolution with a beam diameter of 1.4 um at a focal point located above the chip. Targeted cellular excitation can be achieved by steering the beam through a combination of wavelength tuning and simplified thermo-optical phase shifters with a single electrical input for each of transverse beam steering and selection of the focal plane.
P. Alonso‐González, Alexey Y. Nikitin, Federico Golmar
et al.
A controlled launch for plasmons To create nanophotonic devices, engineers must combine large-scale optics with tiny nanoelectronics. Plasmons, the collective light-induced excitations of electrons at a metal's surface, can bridge that difference in size scales. Alonso-Gonzalez et al. placed structured gold “antennas” on top of a graphene layer to launch and propagate plasmonic excitations into the graphene. By carefully designing the antennas, the researchers could engineer the wavefronts of the plasmons and control the direction of propagation. This approach illustrates a versatile approach for the development of nanophotonics. Science, this issue p. 1369 Structured gold antennas are used to launch plasmons into graphene, engineer their wavefronts, and control their propagation. Graphene plasmons promise unique possibilities for controlling light in nanoscale devices and for merging optics with electronics. We developed a versatile platform technology based on resonant optical antennas and conductivity patterns for launching and control of propagating graphene plasmons, an essential step for the development of graphene plasmonic circuits. We launched and focused infrared graphene plasmons with geometrically tailored antennas and observed how they refracted when passing through a two-dimensional conductivity pattern, here a prism-shaped bilayer. To that end, we directly mapped the graphene plasmon wavefronts by means of an imaging method that will be useful in testing future design concepts for nanoscale graphene plasmonic circuits and devices.
Kenta Yamamura, Takaya Sugiura, Yuta Watanabe
et al.
This study proposes a sub-kHz clock generator by the room light illumination designed on-chip CMOS LSI chips. It generates a clock from a flicker in room light by receiving on-chip integrated photovoltaic cell, and extracts by low-pass filters, a comparator, Schmidt trigger and D-flip-flop to shape to digital signal. The system implements two photovoltaic cells of a large cell for power generation and a small cell for photo-detection that enables standalone operations. The system was designed on 0.18 <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>m standard CMOS process, and both the simulation and experimental results validated the operation. By adding D-flip-flops at the output enables to modify the clock to <inline-formula><tex-math notation="LaTeX">$1/n$</tex-math></inline-formula> values that expands the applications.
Kilian Baudin, Josselin Garnier, Adrien Fusaro
et al.
Classical nonlinear waves exhibit, as a general rule, an irreversible process of thermalization toward the Rayleigh-Jeans equilibrium distribution. On the other hand, several recent experiments revealed a remarkable effect of spatial organization of an optical beam that propagates through a graded-index multimode optical fiber (MMF), a phenomenon termed beam self-cleaning. Our aim here is to evidence the qualitative impact of disorder (weak random mode coupling) on the process of Rayleigh-Jeans thermalization by considering two different experimental configurations. In a first experiment, we launch speckle beams in a relatively long MMF. Our results report a clear and definite experimental demonstration of Rayleigh-Jeans thermalization through light propagation in MMFs, over a broad range of kinetic energy (i.e., degree of spatial coherence) of the injected speckle beam. In particular, the property of energy equipartition among the modes is clearly observed in the condensed regime. The experimental results also evidence the double turbulence cascade process: while the power flows toward the fundamental mode (inverse cascade), the energy flows toward the higher-order modes (direct cascade). In a 2nd experiment, a coherent laser beam is launched into a relatively short MMF length. It reveals an effect of beam cleaning driven by an incipient process of Rayleigh-Jeans thermalization. As discussed through numerical simulations, the fast process of Rayleigh-Jeans thermalization observed in the 1st experiment can be attributed due to a random phase dynamics among the modes, which is favoured by the injection of a speckle beam and the increased impact of disorder in the long fiber system.
Kim Myeongseop, Lee Hee Ryung, Ossikovski Razvigor
et al.
We investigate a possibility of producing the quantitative optical metrics to characterize the evolution of gastric tissue from healthy conditions via inflammation to cancer by using Mueller microscopy of gastric biopsies, regression model and statistical analysis of the predicted images. For this purpose the unstained sections of human gastric tissue biopsies at different pathological conditions were measured with the custom-built Mueller microscope. Polynomial regression model was built using the maps of transmitted intensity, retardance, dichroism and depolarization to generate the predicted images. The statistical analysis of predicted images of gastric tissue sections with multi-curve fit suggests that Mueller microscopy combined with data regression and statistical analysis is an effective approach for quantitative assessment of the degree of inflammation in gastric tissue biopsies with a high potential in clinical applications.
Maik Meudt, Andreas Henkel, Maximilian Buchmüller
et al.
Waveguide gratings are used for applications such as guided-mode resonance filters and fiber-to-chip couplers. A waveguide grating typically consists of a stack of a single-mode slab waveguide and a grating. The filling factor of the grating with respect to the mode intensity profile can be altered via changing the waveguide’s refractive index. As a result, the propagation length of the mode is slightly sensitive to refractive index changes. Here, we theoretically investigate whether this sensitivity can be increased by using alternative waveguide grating geometries. Using rigorous coupled-wave analysis (RCWA), the filling factors of the modes of waveguide gratings supporting more than one mode are simulated. It is observed that both long propagation lengths and large sensitivities with respect to refractive index changes can be achieved by using the intensity nodes of higher-order modes.
The average Raman signal power obtained in a modulated optical trap is dependent on the Brownian motion - therefore hydrodynamic properties of the trapped particle. Hence, in addition to the molecular properties obtained from the Raman signal, it is possible to study hydrodynamic properties (e.g. size) of the particle by analyzing the change in the average Raman power as a function of modulation frequency. Our results, based on the over-damped Langevin equation, show that several minimas exist for the Raman signal at unique modulating frequencies for a given particle size and signal acquisition time. In typical experimental conditions, such minimas can be as low as 50% of the Raman signal in an unmodulated trap.
A novel design of a grating-based optical pulse compressor is proposed. The proposed compressor provides a large group delay dispersion while keeping the compressor linear size small. The design of the proposed compressor is based on a traditional Treacy compressor with a straightforward modification of inserting two lenses between the compressor's gratings. This simple alternation aims to substantially increase group delay dispersion of the compressor or alternatively to decrease the compressor size while maintaining its group delay dispersion. A theoretical description of the enhanced compressor has been developed in the paraxial approximation. A detailed numerical model has been built to calculate the compressor parameters more accurately. These theoretical studies have revealed that the enhanced optical compressor provides a significant increase in the group delay dispersion compared to a standard Treacy compressor.
The non-volatile memory is a crucial functionality for a wide range of applications in photonic integrated circuits, however, it still poses a challenge in silicon photonic technology. This problem has been overcome in the microelectronic industry by using SONOS (silicon-oxide-nitride-oxide-silicon) memory cells, in which the non-volatility is enabled by a dielectric trapping layer such as silicon nitride. Analogously, in this work, a similar approach in which the nitride has been replaced by a hafnium oxide layer, named as SAHAS configuration, is proposed for enabling a programmable erasable photonic memory fully compatible with the silicon platform. The structure features an efficient performance with writing and erasing times of 100 µs, retention times over 10 years and energy consumption in the pJ range, which improve the current SONOS or floating gate based photonic approaches that exploit the plasma dispersion effect in silicon. The proposed non-volatile photonic memory device shows an extinction ratio above 12 dB and insertion losses below 1 dB in a compact footprint. In addition, because the memory is optically read, ultrafast access times in the picosecond range are also achieved.