Advanced Photonics Research最新文献

We present a modern dual-channel surface plasmon resonance (SPR) biosensor that combines advanced photonic crystal fiber (PCF) design with machine learning (ML) techniques to achieve high sensitivity and accurate prediction. The proposed sensor performs very well over a wide refractive index range of 1.33–1.45, showing a wavelength sensitivity of 32 000 nm/RIU, amplitude sensitivity of 2338 RIU⁻¹, and a spectral resolution of 3.13 × 10⁻⁶ RIU. It operates effectively within the wavelength range of 550–1310 nm using gold as the plasmonic material and achieves a high figure of merit of 1333 due to strong light–plasmon interaction. The model design and simulation are performed by (FEM) finite element method method in COMSOL Multiphysics v6.2. After that, to automate the optimization process, ML models are applied in combination of random forest, gradient boosting, and XGBoost model; the combined model has R² value of 0.9771 based on training data from existing studies. By combining this three different ML models, the prediction error minimized than the single individuals’ performance. Overall, integrating PCF design with ML offers a promising path toward automated optimization for PCF-based SPR sensor, resulting in highly sensitive and reliable biosensing for various biological and chemical sensing.

We present a modern dual-channel surface plasmon resonance (SPR) biosensor that combines advanced photonic crystal fiber (PCF) design with machine learning (ML) techniques to achieve high sensitivity and accurate prediction. The proposed sensor performs very well over a wide refractive index range of 1.33–1.45, showing a wavelength sensitivity of 32 000 nm/RIU, amplitude sensitivity of 2338 RIU⁻¹, and a spectral resolution of 3.13 × 10⁻⁶ RIU. It operates effectively within the wavelength range of 550–1310 nm using gold as the plasmonic material and achieves a high figure of merit of 1333 due to strong light–plasmon interaction. The model design and simulation are performed by (FEM) finite element method method in COMSOL Multiphysics v6.2. After that, to automate the optimization process, ML models are applied in combination of random forest, gradient boosting, and XGBoost model; the combined model has R² value of 0.9771 based on training data from existing studies. By combining this three different ML models, the prediction error minimized than the single individuals’ performance. Overall, integrating PCF design with ML offers a promising path toward automated optimization for PCF-based SPR sensor, resulting in highly sensitive and reliable biosensing for various biological and chemical sensing.

The advancement of terahertz technology is impeded by a lack of viable options for dynamic reconfigurability in compact systems with fixed low-loss interconnect. To address this absence, we bring conductive walls into proximity with an unclad microscale silicon waveguide core and thereby supply additional boundary conditions to manipulate guided waves through evanescent interaction. This is analogous to a fiber squeezer, in which a dielectric waveguide's dispersion is manipulated via enclosing walls, but in this case, a crucial distinction is that there is no physical contact whatsoever. Analytical and numerical investigations of this phenomenon show that the presence of the conductive walls increases the cutoff frequency and alters the dispersion profile of the waveguide. We implement proof-of-concept demonstrations that exploit this effect to realize mechanically tunable terahertz filters of two types: a high-pass filter and a resonant notch, operating at ∼300 GHz. This experimental demonstration utilizes a featureless straight dielectric waveguide, and the desired frequency-selective behavior is implemented contactlessly, and hence reversibly, having made no modification to the waveguide core. The capability for on-demand dispersion tuning of low-loss terahertz waveguides holds the potential to realize a broad range of practical reconfigurable systems to support diverse applications of terahertz waves.

The advancement of terahertz technology is impeded by a lack of viable options for dynamic reconfigurability in compact systems with fixed low-loss interconnect. To address this absence, we bring conductive walls into proximity with an unclad microscale silicon waveguide core and thereby supply additional boundary conditions to manipulate guided waves through evanescent interaction. This is analogous to a fiber squeezer, in which a dielectric waveguide's dispersion is manipulated via enclosing walls, but in this case, a crucial distinction is that there is no physical contact whatsoever. Analytical and numerical investigations of this phenomenon show that the presence of the conductive walls increases the cutoff frequency and alters the dispersion profile of the waveguide. We implement proof-of-concept demonstrations that exploit this effect to realize mechanically tunable terahertz filters of two types: a high-pass filter and a resonant notch, operating at ∼300 GHz. This experimental demonstration utilizes a featureless straight dielectric waveguide, and the desired frequency-selective behavior is implemented contactlessly, and hence reversibly, having made no modification to the waveguide core. The capability for on-demand dispersion tuning of low-loss terahertz waveguides holds the potential to realize a broad range of practical reconfigurable systems to support diverse applications of terahertz waves.

Physical unclonable functions (PUFs) are the new paradigm for the development of anticounterfeiting devices. Optical PUFs, which use the properties of light and how it interacts with materials to create unique identifiers, are attractive due to their high complexity. Cholesteric liquid crystals (CLCs), with their peculiar optical properties, are excellent candidates for optical PUF fabrication. Here, we present new fabrication methods to easily obtain complex random optical patterns, resembling human fingerprints, in CLC microspheres by exploiting temperature variations or mechanical stresses. Both methods enable large-scale production of unclonable identifiers, easy to be encapsulated in polymeric thin films to create flexible anticounterfeiting labels. The authentication procedure of the labels is performed through image recognition algorithms. Through this procedure, an additional security feature is added. Each set of labels is used to generate a signature of the set itself. The signature represents a further and strong encoding level that guarantees the security of the labels against cyberattacks.

Physical unclonable functions (PUFs) are the new paradigm for the development of anticounterfeiting devices. Optical PUFs, which use the properties of light and how it interacts with materials to create unique identifiers, are attractive due to their high complexity. Cholesteric liquid crystals (CLCs), with their peculiar optical properties, are excellent candidates for optical PUF fabrication. Here, we present new fabrication methods to easily obtain complex random optical patterns, resembling human fingerprints, in CLC microspheres by exploiting temperature variations or mechanical stresses. Both methods enable large-scale production of unclonable identifiers, easy to be encapsulated in polymeric thin films to create flexible anticounterfeiting labels. The authentication procedure of the labels is performed through image recognition algorithms. Through this procedure, an additional security feature is added. Each set of labels is used to generate a signature of the set itself. The signature represents a further and strong encoding level that guarantees the security of the labels against cyberattacks.

Optical Transient Grating Spectroscopy

In their Research Article (10.1002/adpr.202500233), Alexei A. Maznev, Riccardo Cucini, and co-workers present an approach for exciting standing dipolar spin waves with a controlled wave vector in a ferrimagnetic thin film. By separating magnons from phonons, transient grating spectroscopy emerges as a powerful optical gateway to multiscale magnonics.

Optical Transient Grating Spectroscopy

In their Research Article (10.1002/adpr.202500233), Alexei A. Maznev, Riccardo Cucini, and co-workers present an approach for exciting standing dipolar spin waves with a controlled wave vector in a ferrimagnetic thin film. By separating magnons from phonons, transient grating spectroscopy emerges as a powerful optical gateway to multiscale magnonics.