ACS Photonics最新文献

We have developed an integrated dual-band photonic filter (PF) utilizing equivalent chirped four-phase-shifted sidewall-sampled Bragg gratings (4PS-SBG) on a silicon-on-insulator platform. Using the reconstruction equivalent-chirp technique, we designed linearly chirped 4PS Bragg gratings with two π-phase shifts (π-PSs) positioned at 1/3 and 2/3 of the grating cavity, introducing two passbands in the + first order channel. Leveraging the significant thermo-optic effect of silicon, dual-band tuning is achieved through integrated microheaters (MHs) on the chip surface. By varying the injection currents from 0 to 85 mA into the MHs, the device demonstrates continuous and wide-range optical frequency division performance, with the frequency interval between the two passbands adjustable from 52.1 to 439.5 GHz. Four notable frequency division setups at 100, 200, 300, and 400 GHz were demonstrated using a 100 GHz, 1535 nm semiconductor passive mode-locked laser as the light source.

Advancements in three-dimensional (3D) photolithography are crucial for enhancing the performance of devices in applications ranging from energy storage and sensors to microrobotics. Proximity-field nanopatterning (PnP), which utilizes light-shaping phase masks, has emerged as a promising method to boost productivity. This study presents a swift and effective strategy for the design of phase masks tailored to the PnP process. Conventional design methodologies, grounded in basic optical theories, have been constrained by the simplicity and limited contrast of the resulting nanopatterns. Our approach, which merges the use of a frequency-domain electromagnetic solver─termed the convergent Born series─with gradient-based optimization and GPU acceleration, successfully addresses these shortcomings. The proposed solver outperforms CPU-intensive commercial FDTD software in our 2D test case by approximately 30 times, and its computational advantage increases in 3D simulations. This approach facilitates the creation of complex, high-contrast nanostructures within practical timeframes. We validate our method’s effectiveness by engineering phase masks to produce distinct hologram patterns, such as single and double helices, thereby underscoring its utility for pioneering nanophotonic devices. Our findings propel the PnP process forward, ushering in novel avenues for the creation of sophisticated 3D nanostructures with superior optical and mechanical features.

Photodynamic therapy and photothermal therapy have emerged as indispensable modalities to treat diseases. However, their efficacy is hindered by the substantial light scattering within tissues, preventing light transmission effectively to targeted lesion sites. Various existing devices aimed at mitigating light scattering typically exhibit invasiveness and complexity. In this work, we propose an approach that utilizes a portable acoustic holographic optical waveguide device to mitigate light scattering by manipulating the refractive index within tissues. This manipulation allows in situ modulation of scattered light, thereby promoting the concentration of photon energy. We demonstrated that the device can mitigate light scattering in a medium through simulation and optical imaging experiments. Second, we demonstrated in both photothermal and photodynamic experiments that the device can enhance the rate of temperature rise in the medium and the rate of singlet oxygen (¹O₂) generation, respectively. It is foreseeable that this versatility in overcoming light scattering can augment the outcomes of phototherapy, offering a noninvasive, portable, and robust method.

Plasmonic random lasers involve the interaction of emitters and metallic scatterers in extremely small mode volumes, which give rise to interesting nonlinear optical phenomena in random nanocavities. Here, we present an anomalous lasing behavior in a plasmonic random laser composed of vertically standing ZnO nanorods decorated with Au nanoislands and infiltrated with a dye-doped polymer matrix. The coupling of random laser modes to plasmonic nanocavities with high absorption losses results in unusual lasing behavior. At higher pump fluences, the nonlinear optical behavior of the Au nanoislands induces a second kink in the threshold characteristics. Various statistical tools have been employed to analyze the intensity fluctuations of the random laser modes, validating this unique lasing behavior.

The field of optoelectronics has witnessed a surge of interest in hybrid structures that combine colloidal quantum dots (QDs) and two-dimensional (2D) materials. These structures are expected to offer a synergistic blend of high responsivity and rapid response times. However, the potential of QD-based photodetectors has been consistently undermined by the limited carrier mobility in QD films, which arises from the inherent disordered QD and ligand packing produced through conventional fabrication methods. It introduces a pioneering approach to address this limitation: the successful growth and lossless transfer of a micrometer-scale mesocrystalline, oriented packed CsPbBr₃ QD superlattice (SL) onto 2D WS₂. The effective coupling within these SLs endows them with quasi-2D material characteristics and, when integrated with the intrinsic 2D properties of WS₂, results in a photodetector with exceptional performance. Under 405 nm illumination, it demonstrates a remarkable responsivity of 91.24 A/W, a specific detectivity of 1.15 × 10¹¹ Jones, and swift response times of 160 μs/380 μs. These performance metrics exceed those of disordered CsPbBr₃ QDs/WS₂ photodetector prepared by spin-coating, underscoring the superior optoelectronic properties of the SL/WS₂ hybrid structure. This breakthrough not only contributes to the design of high-performance photodetectors but also facilitates transformative progress in the field of optoelectronic technologies.