Photoacoustic microscopy (PAM) operating within the 1.7-μm absorption window holds great promise for the quantitative imaging of lipids in various biologi

Photoacoustic microscopy (PAM) operating within the 1.7-μm absorption window holds great promise for the quantitative imaging of lipids in various biological tissues. Despite its potential, the effectiveness of lipid-based PAM has been limited by the performance of existing nanosecond laser sources at this wavelength. In this work, we introduce a 1725-nm hybrid optical parametric oscillator emitter (HOPE) characterized by a narrow bandwidth of 1.4 nm, an optical signal-to-noise ratio (OSNR) of approximately 34 dB, and a high spectral energy density of up to 480 nJ/nm. This advanced laser source significantly enhances the sensitivity of photoacoustic imaging, allowing for the detailed visualization of intrahepatic lipid distributions with an impressive maximal contrast ratio of 23.6:1. Additionally, through segmentation-based analysis of PAM images, we were able to determine steatosis levels that align with clinical assessments, thereby demonstrating the potential of our system for high-contrast, label-free lipid quantification. Our findings suggest that the proposed 1725-nm HOPE source could be a powerful tool for biomedical research and clinical diagnostics, offering a substantial improvement over current technologies in the accurate and non-invasive assessment of lipid accumulation in tissues.show less

Chronic diabetic wounds, a common and severe complication of diabetes, are characterized by their inability to heal due to impaired blood and oxygen suppl

Chronic diabetic wounds, a common and severe complication of diabetes, are characterized by their inability to heal due to impaired blood and oxygen supply. In addition to glycemic control, various clinical treatments such as wound dressings, hyperbaric oxygen therapy, and phototherapy have been employed to manage these wounds. Low-level light therapy has emerged as an effective, noninvasive, and painless therapeutic approach for wound management. However, the bulkiness of traditional light sources and the need for frequent clinic visits have limited its widespread adoption. We have developed a wearable, flexible light-emitting bandage with cyanobacterial impregnation (LEB@Cyan). The bioactive bandage is designed to provide sustained oxygen generation and robust photobiomodulation, promoting keratinocyte migration, fibroblast proliferation, and angiogenesis. This addresses the hypoxic conditions and enhances bioenergetic supply to accelerate the healing process of diabetic wounds. In detail, the wound area of diabetic rats treated with LEB@Cyan showed significant reductions of 74.76% and 96.32% compared with that of LEB-treated diabetic rats and untreated diabetic rats, respectively. Such self-oxygenated wearable light-emitting fabric holds great promise for future clinical and commercial applications, potentially revolutionizing the management of chronic diabetic wounds.show less

Metasurface modeling, designs, and applications using computational approaches are by now well established as an essential pillar in photonics, physics, a

Metasurface modeling, designs, and applications using computational approaches are by now well established as an essential pillar in photonics, physics, and materials science. The past years have witnessed tremendous advances in methodologies and technologies to unearth the intricate light–matter interaction and promote adaptive metadevices. They have pushed the studies of metasurfaces from early passive, reconfigurable modalities to the next generation of intelligent metasurfaces. In this review, we elaborate general architecture for intelligent metasurfaces, constructed by the algorithm layer, tunable metasurface layer, and application layer. We first discuss a variety of deep learning models, ranging from the fundamental neural networks inspired by computer science to sophisticated algorithms embedded with physical specialty, highlighting their potential in the forward prediction, inverse design, and spectral correlation of metasurfaces. We then discuss adaptive metadevices in the main applications of invisibility cloaks, smart vision, intelligent sensing, and wireless communication. Finally, we pinpoint current challenges and future perspectives to embrace the coming era of intelligent metasurfaces.show less

Electric field poling of electro-optic polymer (EOP) in hybrid waveguides is highly challenging due to the discontinuity in electric field distribution, w

Electric field poling of electro-optic polymer (EOP) in hybrid waveguides is highly challenging due to the discontinuity in electric field distribution, which leads to a low Pockels electro-optic (EO) coefficient or dielectric breakdown. We propose the segmented poling technique in Si3N4/EOP hybrid waveguides to address this challenge. Dipolar chromophores near an electrode interface first align with a weak poling electric field, and then a strong field is applied for the chromophore alignment near the waveguide interface. This technique effectively avoids dielectric breakdown, and the tuning efficiency of the EO Mach–Zender interferometer (MZI) filters is improved from 31.7 pm/V to higher than 50 pm/V, with a highest Pockels coefficient of 114 pm/V.show less