We report on controlling the spontaneous emission (SE) rate of a molybdenum disulfide (MoS₂) monolayer coupled with a planar photonic crystal (PPC) nanocavity. Spatially resolved photoluminescence (PL) mapping shows strong variations of emission when the MoS₂ monolayer is on the PPC cavity, on the PPC lattice, on the air gap, and on the unpatterned gallium phosphide substrate. Polarization dependences of the cavity-coupled MoS₂ emission show a more than 5 times stronger extracted PL intensity than the un-coupled emission, which indicates an underlying cavity mode Purcell enhancement of the MoS₂ SE rate exceeding a factor of 70.

Diabetic retinopathy (DR) is a common complication of diabetes mellitus that disrupts the retinal microvasculature and is a leading cause of vision loss globally. Recently, optical coherence tomography angiography (OCTA) has been developed to image the retinal microvasculature, by generating 3-dimensional images based on the motion contrast of circulating blood cells. OCTA offers numerous benefits over traditional fluorescein angiography in visualizing the retinal vasculature in that it is non-invasive and safer; while its depth-resolved ability makes it possible to visualize the finer capillaries of the retinal capillary plexuses and choriocapillaris. High-quality OCTA images have also enabled the visualization of features associated with DR, including microaneurysms and neovascularization and the quantification of alterations in retinal capillary and choriocapillaris, thereby suggesting a promising role for OCTA as an objective technology for accurate DR classification. Of interest is the potential of OCTA to examine the effect of DR on individual retinal layers, and to detect DR even before it is clinically detectable on fundus examination. We will focus the review on the clinical applicability of OCTA derived quantitative metrics that appear to be clinically relevant to the diagnosis, classification, and management of patients with diabetes or DR. Future studies with longitudinal design of multiethnic multicenter populations, as well as the inclusion of pertinent systemic information that may affect vascular changes, will improve our understanding on the benefit of OCTA biomarkers in the detection and progression of DR.

Diabetic retinopathy (DR) is a common microvascular ocular complication of diabetes and is a leading cause of blindness in the working-age population.^1,2 The population with diabetes globally is estimated to reach 366 million in 2030, with 34.6% having DR and 7% having vision-threatening DR.^3,4

We demonstrate the controlled enhancement of photoresponsivity in a graphene photodetector by coupling to slow light modes in a long photonic crystal linear defect cavity. Near the Brillouin zone (BZ) boundary, spectral coupling of multiple cavity modes results in broad-band photocurrent enhancement from 1530 nm to 1540 nm. Away from the BZ boundary, individual cavity resonances enhance the photocurrent eight-fold in narrow resonant peaks. Optimization of the photocurrent via critical coupling of the incident field with the graphene-cavity system is discussed. The enhanced photocurrent demonstrates the feasibility of a wavelength-scale graphene photodetector for efficient photodetection with high spectral selectivity and broadband response.

Cardiac diseases are among the leading causes of morbidity and mortality globally. During the progression of heart disease, microstructural heterogeneity within myocardial tissue could lead to an increased risk of life-threatening cardiac diseases such as ventricular arrhythmias and heart failure.^1,2 Visualization of the features in the endomyocardial layer may shed light on the correlations between the microstructural and functional changes in the tissue, which are important for guiding diagnostic procedures and clinical treatment such as reverse remodeling therapy,³ radiofrequency ablation,⁴ and endomyocardial biopsy (EMB).^5,6 Particularly, despite the controversy of EMB, it is still the most frequently used method for surveillance of cardiac allograft rejection and for the diagnosis of unexplained ventricular dysfunction.⁶ The main reason is that most of the well-established medical imaging modalities (magnetic resonance imaging,⁷ echocardiography,⁸ and computed tomography⁹) do not have sufficient resolution to provide the cellular-level assessment of the myocardium that the biopsy can otherwise provide.⁵ Optical coherence tomography (OCT) is a high-speed, nondestructive imaging tool that is able to produce cross-sectional and three-dimensional (3-D) images with cellular/subcellular axial resolution within millimeter-scale penetration depth of biological samples and has been applied in a wide range of medical imaging applications.^10,11