This paper presents a parallel two-photon lithography method, marked by high uniformity, using a digital mirror device (DMD) and a microlens array (MLA) system to generate numerous, independently controlled femtosecond (fs) laser foci. Individual focus switching and intensity adjustment are possible. For parallel fabrication in the experiments, a 1600-laser focus array was created. The focus array's intensity uniformity impressively reached 977%, showcasing a pinpoint 083% intensity-tuning precision for each focal point. A uniformly arrayed dot pattern was created to showcase the simultaneous fabrication of sub-diffraction-limited features, meaning features smaller than 1/4 wavelength or 200 nanometers. The potential of multi-focus lithography lies in its ability to expedite the creation of massive 3D structures that are arbitrarily intricate, featuring sub-diffraction scales, and operating at a fabrication rate three orders of magnitude faster than current methods.
Biological engineering and materials science are just two examples of the diverse fields where low-dose imaging techniques prove invaluable. Phototoxicity and radiation-induced damage to samples can be mitigated by utilizing low-dose illumination. Poisson noise and additive Gaussian noise, unfortunately, become significant contributors to the degradation of image quality, particularly in low-dose imaging scenarios, affecting key aspects such as signal-to-noise ratio, contrast, and resolution. Employing a deep neural network, we develop a low-dose imaging denoising technique that incorporates a statistical noise model within its framework. Using a pair of noisy images in place of definitive target labels, the network's parameters are fine-tuned based on the statistical properties of the noise. Simulation data from optical and scanning transmission electron microscopes, under varying low-dose illumination conditions, are used to evaluate the proposed method. Within a dynamic system, to capture two noisy measurements of the same data, we designed an optical microscope that concurrently acquires two images, each exhibiting independent and identically distributed noise. Reconstruction of a biological dynamic process under low-dose imaging conditions is accomplished using the proposed method. Our experimental results on optical microscopes, fluorescence microscopes, and scanning transmission electron microscopes demonstrate the effectiveness of the proposed method, exhibiting improved signal-to-noise ratios and spatial resolution in the reconstructed images. We believe the proposed method's utility extends to diverse low-dose imaging systems, encompassing both biological and materials science applications.
Quantum metrology provides a vast improvement in measurement precision, going far beyond the theoretical limits of classical physics. For ultrasensitive tilt angle measurements across a wide range of tasks, we present a Hong-Ou-Mandel sensor acting as a photonic frequency inclinometer, ranging from determining mechanical tilt angles, to tracking the rotation/tilt dynamics of light-sensitive biological and chemical materials, and enhancing optical gyroscope performance. Estimation theory indicates that a wider spectrum of single-photon frequencies and a greater frequency difference within color-entangled states are factors that can elevate the achievable resolution and sensitivity. Employing Fisher information analysis, the photonic frequency inclinometer dynamically optimizes the sensing position, even when confronted with experimental imperfections.
The S-band polymer-based waveguide amplifier's manufacture is complete, but augmenting its gain performance continues to be a significant challenge. By facilitating energy exchange between diverse ionic species, we accomplished a noteworthy increase in the efficiency of Tm$^3+$ 3F$_3$ $ ightarrow$ 3H$_4$ and 3H$_5$ $ ightarrow$ 3F$_4$ transitions, thereby bolstering emission at 1480 nm and upgrading gain within the S-band. The polymer-based waveguide amplifier exhibited a maximum gain of 127dB at 1480nm after doping its core layer with NaYF4Tm,Yb,Ce@NaYF4 nanoparticles, surpassing earlier research by 6dB. Monocrotaline Our findings demonstrated a substantial enhancement in S-band gain performance, attributable to the gain improvement technique, and offered a blueprint for optimizing gain across various communication bands.
Inverse design, though useful for producing ultra-compact photonic devices, encounters limitations stemming from the high computational power needed for the optimization processes. Stoke's theorem establishes a direct relationship between the comprehensive alteration at the external perimeter and the integrated variation over internal subdivisions, enabling the disaggregation of a sophisticated device into simpler constituent units. This theorem, thus, becomes an integral part of our novel inverse design methodology for creating optical devices. Inverse design techniques, in comparison with conventional methods, experience a substantial reduction in computational intricacy through regional optimization strategies. Optimizing the entire device region takes roughly five times longer than the overall computational time. For experimental verification of the proposed methodology, a monolithically integrated polarization rotator and splitter was designed and fabricated. The device effectively executes polarization rotation (TE00 to TE00 and TM00 modes) and power splitting, precisely managing the allocated power ratio. The average insertion loss, as exhibited, is less than 1 dB, and the crosstalk level is less than -95 dB. These findings validate both the benefits and the practicality of the new design methodology for consolidating multiple functionalities into a single monolithic device.
This paper details a novel approach involving an optical carrier microwave interferometry (OCMI) three-arm Mach-Zehnder interferometer (MZI) for interrogation and experimental demonstration of a fiber Bragg grating (FBG) sensor. In our sensing method, the Vernier effect, resulting from the superposition of the interferogram created by the interference of the three-arm MZI's middle arm with the sensing and reference arms, is utilized to improve the system's sensitivity. The OCMI-based three-arm-MZI's simultaneous interrogation of the sensing fiber Bragg grating (FBG) and the reference FBG offers a perfect solution to cross-sensitivity issues, such as those encountered with other systems. Temperature variations and strain levels influence sensors utilizing optical cascading for the Vernier effect. An experimental study of strain sensing using the OCMI-three-arm-MZI based FBG sensor shows it to be 175 times more sensitive than the two-arm interferometer-based FBG sensor. There was a marked reduction in temperature sensitivity, plummeting from 371858 kHz per degree Celsius to a much lower 1455 kHz per degree Celsius. The sensor's notable strengths, including its high resolution, high sensitivity, and minimal cross-sensitivity, underscore its potential for precise health monitoring in demanding environments.
Guided modes within coupled waveguides constructed from negative-index materials, devoid of gain or loss, are subject to our analysis. Our research reveals that non-Hermitian phenomena and structural geometry factors jointly determine the existence of guided modes. The non-Hermitian effect, fundamentally distinct from parity-time (P T) symmetry, finds an explanation within a basic coupled-mode theory utilizing anti-P T symmetry. A review of the implications of exceptional points and slow-light effects is offered. Loss-free negative-index materials hold considerable potential, as highlighted by this work, for advancing the study of non-Hermitian optics.
Mid-IR optical parametric chirped pulse amplifiers (OPCPA) are explored regarding dispersion management to generate high-energy few-cycle pulses beyond the 4-meter mark. The scope of feasible higher-order phase control is circumscribed by the pulse shapers operative within this spectral region. To achieve the generation of high-energy pulses at 12 meters, we propose alternative mid-infrared pulse-shaping strategies, utilizing a germanium prism pair and a sapphire prism Martinez compressor, powered by the signal and idler pulses from a mid-wave infrared optical parametric chirped pulse amplification system. PCR Reagents We additionally examine the maximal achievable bulk compression in silicon and germanium for high-energy pulses exceeding a millijoule.
A foveated approach to local super-resolution imaging is presented, using a super-oscillation optical field. Initially, the integral equation ensuing from the foveated modulation device's diffraction process is formulated, the objective function and constraints are defined, and the amplitude modulation device's structural parameters are subsequently optimized using a genetic algorithm. Secondly, the data, having been resolved, were subsequently imported into the software to facilitate point diffusion function analysis. Through a study of various ring band amplitude types, we observed the 8-ring 0-1 amplitude type to possess the highest super-resolution performance. Based on the simulation, the fundamental experimental apparatus is constructed, and the parameters of the super-oscillatory device are loaded into the spatial light modulator optimized for amplitude modulation. This allows the foveated, locally super-resolved imaging system based on super-oscillation to achieve high-contrast imaging across the entire field of view and super-resolution imaging within the focused region. thermal disinfection This method ultimately enables a 125-times super-resolution magnification in the foveated region, providing super-resolution imaging of the local area without altering the resolution of other fields. The experimental results demonstrate the system's feasibility and effectiveness.
This study experimentally validates a four-mode polarization/mode-insensitive 3-dB coupler design, centered around an adiabatic coupler. The first two transverse electric (TE) modes and the first two transverse magnetic (TM) modes are accommodated by the proposed design. Within the 70nm optical range (from 1500nm to 1570nm), the coupler's performance is demonstrated by a maximum insertion loss of 0.7dB, a crosstalk maximum of -157dB and a maximum power imbalance of 0.9dB.