Advanced Photonics Research最新文献

Orbital Angular Momentum

In article number 2400008, Edouard Hertz and co-workers show how ultrashort spatially structured beams can sculpt a sample of gas-phase molecules in three dimensions so as to produce a spatial pattern of aligned molecules whose shape and temporal evolution allow to restore the spatial light information on a time-delayed reading pulse. This property can be exploited to establish versatile optical processing of orbital angular momentum fields or to design new photonic devices.

Pulsed Laser Ablation

In article number 2300290, Bilal Gökce and co-workers present a cost-effective solution that enhances pulsed laser ablation in liquids (PLAL) productivity four-fold compared to single-beam PLAL. The cover art showcases the proposed multi-beam method, illustrating the nanoparticle production rate increase while maintaining nanoparticle quality. This breakthrough addresses the nanoparticle synthesis scalability challenge, paving the way for broader industrial applications.

The fabrication and characterization of an all polymers-based bulk heterojunction type organic photodiode having a narrowband response in the near-infrared spectral region with full width at half-maxima of 63 nm is reported. The active layer of the photodiode constitutes a 1:1 (by weight) blend of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PCE10) and poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diy1]-alt-5,5′-(2,2′-dithiophene)} (N2200) deposited using solution processing. The device exhibits a linear dynamic range of 35 dB, response speed of 893 kHz, and specific-detectivity of 10⁹ Jones at 808 nm excitation wavelength. The narrowband response is achieved using the charge collection narrowing mechanism in a 2.7 μm thick junction device.

Proper derivation of CH₃NH₃PbX₃ (MAPbX₃; where X = Cl⁻, Br⁻, I⁻) optical constants is a critical step toward the development of high-performance perovskite devices. To date, the optical dispersions at all wavelengths have been inconsistently characterized by under-approximating or omitting anomalous spectral features. Herein, a rigorous optical dispersion data analysis of single-crystal MAPbBr₃ involving variable-angle spectroscopic ellipsometry data appended with transmission intensity data is presented. This approach yields a more robust derivation of the refractive index and extinction coefficient for both anomalous (absorptance) and normal (no absorptance) optical dispersion regimes. Using the derived optical constants, illustrative modeled perovskite solar cell device designs are presented in relation to nonrealistic designs prepared using representative optical constants reported in the literature. In comparison, the derived optical constants enables the modeling of layer thicknesses to maximize absorption by the active layer (MAPbBr₃) and minimize parasitic optical absorptance by the nonactive layers at broad angles of incidence (≈0°–70°). This robust derivation of MAPbBr₃ optical constants is expected to impact the optical dispersion data analysis of all perovskite analogs and expedite targeted development of, for example, solar cell, light-emitting diode, photo- and X-ray/γ-ray detector, and laser system technologies.

This work presents the polarization-dependent behavior of the anapole state in stacked amorphous silicon (a-Si) nanodisks with elliptical geometries. Using SiO₂ as a spacer layer between the a-Si disks, the high index contrast between these materials can be used to significantly reduce the fabrication complexity of the system compared to traditional methods that require additional etching of the spacers. A novel way of continuous tuning of the electric dipole anapole excitation within elliptical stacked a-Si nanoresonators is demonstrated. By rotating the incident electric field's polarization angle, the anapole state can be selectively excited at two distinct wavelength positions separated by 80 nm. Experimental results show characteristic dips in the reflectance of the fabricated elliptical a-Si stacks with wavelength positions between 1135 and 1217 nm depending on the polarization angle of the incident field which is corroborated by FDTD simulations. Through simulating the internal electric field in the resonators and using multipole decomposition, it is shown that the reflectance dips are due to anapole excitation in the individual disks. The capability to excite anapoles at two distinct wavelengths in the same structure has promising implications for the development of tunable sensors, frequency converters, and quantum memory applications.

Broadband analog signal processors utilizing silicon photonics have demonstrated a significant impact in numerous application spaces, offering unprecedented bandwidths, dynamic range, and tunability. In the past decade, microwave photonic techniques have been applied to neuromorphic processing, resulting in the development of novel photonic neural network architectures. Neuromorphic photonic systems can enable machine learning capabilities at extreme bandwidths and speeds. Herein, low-quality factor microring resonators are implemented to demonstrate broadband optical weighting. In addition, silicon photonic neural network architectures are critically evaluated, simulated, and optimized from a radio-frequency performance perspective. This analysis highlights the linear front-end of the photonic neural network, the effects of linear and nonlinear loss within silicon waveguides, and the impact of electrical preamplification.

In recent decades, quantum information technologies have attracted significant attention and experienced rapid development due to their ultrafast processing speeds and high level of information security. A significant trend in this field of study involves the ongoing pursuit of integrating and miniaturizing quantum devices. Metasurfaces, which are artificially designed planar nanostructure arrays with versatile wavefront shaping capabilities, present a promising platform for the development of integrated photonic quantum devices by effectively controlling quantum light in multiple degrees of freedom. In this review, recent advances in the field of quantum photonics facilitated by metasurfaces, encompassing quantum light sources, manipulation and measurement of quantum states, and the intriguing functionalities of quantum metasurfaces, are summarized. Additionally, potential future directions for the advancement of quantum metasurfaces are discussed.

In the efforts to generate a less toxic X-Ray bioimaging contrast agent, a fully organic, radioluminescent nanoparticle system that emits in the near-infrared (NIR) region when excited with an X-Ray source is synthesized using a two-step process. First, red-emitting nanoparticles are fabricated by the emulsion copolymerization of styrene and propargyl acrylate with anthracene, naphthalimide, and rhodamine B methyl methacrylate derivatives. Subsequently, the nanoparticles are modified with silicon phthalocyanine and indocyanine green derivatives via a copper(I)-catalyzed azide/alkyne cycloaddition “click” reaction. By coupling an organic scintillator with four Förster resonance energy transfer-pairing dyes, X-Ray-induced, multiple, sequential energy transfer is exploited to convert ionizing radiation from an X-Ray source into NIR light, which is optimal for biomedical imaging. Proof-of-concept imaging studies show that the X-Ray-induced indocyanine green fluorescence from the particulate system can be visualized through porcine tissue. Additionally, toxicity studies in human embryonic kidney cells indicate that the particles are nontoxic and applicable in vivo.

Ultrafast fiber lasers (UFLs) have become an attractive alternative to solid-state lasers (SSL) due to their excellent beam quality, compactness, environmental stability, and easy thermal management. In the last decade, a significant research effort is spent to identify UFL architectures providing pulse energy, duration, and peak power comparable to those of complex and expensive, Ti:sapphire laser systems and semiconductor saturable absorber mirrors mode-locked, Yb-doped SSL. Lately, Mamyshev oscillators (MOs), relying on offset spectral filtering combined with nonlinear spectral broadening by self-phase modulation, emerge as a promising solution and are rapidly becoming the state of the art for high energy/peak power UFLs based on large-mode-area (LMA) fibers. The focus of this work is the first demonstration of starting of the mode-locking regime in an LMA MO with an affordable passively Q-switched microchip laser. This solution was previously demonstrated only in low-power MO based on single-mode fibers, which are intrinsically easier to seed, if compared to high-gain LMA UFLs, because of the lower amplified spontaneous emission noise floor. This starting technique in an easy-to-implement ring LMA MO at 1 μm is tested. The oscillator provides ≈50 nJ pulses at 12 MHz repetition rate with a minimum pulse duration of ≈50 fs after compression, resulting in MW peak power.

A nanophotonic passively Q-switched lasing element in the near infrared is proposed and theoretically investigated. It consists of a silicon-rich nitride disk resonator enhanced with the contemporary $��{�\text{MoS}�}_2�/�{�\text{WSe}�}_2�$ hetero-bilayer and a graphene monolayer to provide gain and saturable absorption, respectively. The two-dimensional materials are placed on top of the disk resonator and are separated by a spacer of hexagonal boron nitride. $��{�\text{MoS}�}_2�/�{�\text{WSe}�}_2�$ emits at 1128 nm due to the radiative recombination of interlayer excitons after being optically pumped at 740 nm. Optical pumping is conducted in a guided-wave manner aiming at achieving a high overall efficiency by critically coupling to a cavity mode near the pump transition. The response of the proposed pulsed laser is assessed by utilizing a coupled-mode theory framework fed with linear finite-element method simulations, rigorously derived from the Maxwell–Bloch equations. Following a meticulous design process and exploiting the guided pumping scheme, an ultralow lasing threshold of just $��24�.�2��$μW is obtained. Overall, the Q-switched laser delivers pulsed light inside an integrated bus waveguide with mW peak power, ps duration, and GHz repetition rates requiring sub-mW continuous wave pumping. These properties are highly promising for communication applications and highlight the potential of two