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 MoS2 SE rate exceeding a factor of 70.The recent finding that a single atomic layer of transition metal dichalcogenides (TMDs) can exhibit a large, direct bandgap [1-4] opens the possibility of a new range of atomically thin materials for electronic and electro-optic devices.Monolayer molybdenum disulfide (MoS 2 ) has been used to fabricate field-effect transistors (FETs) with a carriermobility of 200 cm 2 V −1 s −1 and On/Off ratios exceeding 10 8 at room temperature, comparable to those obtained in graphene nanoribbon-based FETs [5]. Optical studies have shown that monolayer MoS 2 exhibits a photoluminescence (PL) quantum yield that is enhanced by a factor more than 10 4 compared with the bulk crystal [2,6]. However, the PL efficiency of monolayer MoS 2 is still very low at ∼ 10 −2 because the nonradiative recombination rate 1/τ nr far exceeds

We demonstrate a high-contrast electro-optic modulation of a photonic crystal nanocavity integrated with an electrically gated monolayer graphene. A high quality (Q) factor air-slot nanocavity design is employed for high overlap between the optical field and graphene sheet. Tuning of graphene's Fermi level up to 0.8 eV enables efficient control of its complex dielectric constant, which allows modulation of the cavity reflection in excess of 10 dB for a swing voltage of only 1.5 V. We also observe a controllable resonance wavelength shift close to 2 nm around a wavelength of 1570 nm and a Q factor modulation in excess of three. These observations allow cavity-enhanced measurements of the graphene complex dielectric constant under different chemical potentials, in agreement with a theoretical model of the graphene dielectric constant under gating. This graphene-based nanocavity modulation demonstrates the feasibility of high-contrast, low-power frequency-selective electro-optic nanocavity modulators in graphene-integrated silicon photonic chips.Graphene has intriguing optical properties and enables a range of promising optoelectronic devices [1][2][3][4][5][6][7][8][9]. To enhance the inherently weak light-matter interaction in this single atomic layer material, grahene has been coupled to optical waveguides and cavities [6,[10][11][12][13]. In the limit of wavelength-scale confinement, we recently demonstrated a dramatic enhancement of the light-matter interaction for graphene coupled to a planar photonic crystal (PPC) nanocavity, which reduced the cavity reflection by more than 20 dB [14]. Here, we employ this system to demonstrate a high contrast electro-optical modulation of the cavity reflection, in excess of 10 dB. The modulation is achieved by electrical gating of the graphene monolayer using an electrolyte, which, while slow, shows the fundamental capability arXiv:1211.0458v1 [physics.optics]

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.