Ultracompact bottom-up photonic crystal lasers on silicon-on-insulator

Abstract Compact on-chip light sources lie at the heart of practical nanophotonic devices since chip-scale photonic circuits have been regarded as the next generation computing tools. In this work, we demonstrate room-temperature lasing in 7 × 7 InGaAs/InGaP core-shell nanopillar array photonic crystals with an ultracompact footprint of 2300 × 2300 nm2, which are monolithically grown on silicon-on-insulator substrates. A strong lateral confinement is achieved by a photonic band-edge mode, which is leading to a strong light-matter interaction in the 7 × 7 nanopillar array, and by choosing an appropriate thickness of a silicon-on-insulator layer the band-edge mode can be trapped vertically in the nanopillars. The nanopillar array band-edge lasers exhibit single-mode operation, where the mode frequency is sensitive to the diameter of the nanopillars. Our demonstration represents an important first step towards developing practical and monolithic III-V photonic components on a silicon platform

Direction-selective emission with small angular divergence from a subwavelength aperture using radiative waveguide modes

We investigate experimentally and theoretically the highly direction-selective emission with small angular divergence in a metal-dielectric-metal structure with a subwavelength metal aperture layer. The thicknesses of the dielectric layer and top metal layer play important roles in controlling the emission direction and angular divergence, respectively. Dispersion curve calculations based on the transfer matrix method indicate that the directional emission is mediated by radiative waveguide modes. We show that the directional emission in a metal-dielectric-metal structure is independent of the polarization of the incident light in contrast to plasmonic beaming structures, such as a subwavelength aperture surrounded by surface corrugations with a strong polarization dependence

Lasing in hybrid metal-Bragg nanocavities

We report room-temperature lasing from an optically pumped subwavelength-scale cylindrical InGaAsP pillar surrounded by circular Bragg reflectors on a metal substrate with a dielectric spacer layer. By taking advantage of wide in-plane photonic bandgaps and proper vertical antiresonances, three dielectric Bragg pairs produce a sufficient optical feedback capable of low threshold lasing from the fundamental TE011 mode. A large spontaneous emission coupling into the lasing mode is obtained from the cavity-enhanced Purcell effects and effective suppression of nonlasing modes

Radiation Response Prediction Model Based on Integrated Clinical and Genomic Data Analysis

PURPOSE: The value of the genomic profiling by targeted gene-sequencing on radiation therapy response prediction was evaluated through integrated analysis including clinical information. Radiation response prediction model was constructed based on the analyzed findings. MATERIALS AND METHODS: Patients who had the tumor sequenced using institutional cancer panel after informed consent and received radiotherapy for the measurable disease served as the target cohort. Patients with irradiated tumor locally controlled for more than 6 months after radiotherapy were defined as the durable local control (DLC) group, otherwise, non-durable local control (NDLC) group. Significant genomic factors and domain knowledge were used to develop the Bayesian Network model to predict radiotherapy response. RESULTS: Altogether, 88 patients were collected for analysis. Of those, 41 (43.6%) and 47 (54.4%) patients were classified as the NDLC and DLC group, respectively. Somatic mutations of NOTCH2 and BCL were enriched in the NDLC group, whereas, mutations of CHEK2, MSH2, and NOTCH1 were more frequently found in the DLC group. Altered DNA repair pathway was associated with better local failure-free survival (hazard ratio, 0.40; 95% confidence interval, 0.19 to 0.86; p=0.014). Smoking somatic signature was found more frequently in the DLC group. Area under the receiver operating characteristic curve of the Bayesian network model predicting probability of 6-month local control was 0.83. CONCLUSION: Durable radiation response was associated with alterations of DNA repair pathway and smoking somatic signature. Bayesian network model could provide helpful insights for high precision radiotherapy. However, these findings should be verified in prospective cohort for further individualization.Y

Stress-activated miR-204 governs senescent phenotypes of chondrocytes to promote osteoarthritis development

A progressive loss of cartilage matrix leads to the development of osteoarthritis (OA). Matrix homeostasis is disturbed in OA cartilage as the result of reduced production of cartilage-specific matrix and increased secretion of catabolic mediators by chondrocytes. Chondrocyte senescence is a crucial cellular event contributing to such imbalance in matrix metabolism during OA development. Here, we identify miR-204 as a markedly up-regulated microRNA in OA cartilage. miR-204 is induced by transcription factors GATA4 and NF-kappa B in response to senescence signals. Up-regulated miR-204 simultaneously targets multiple components of the sulfated proteoglycan (PG) biosynthesis pathway, effectively shutting down PG anabolism. Ectopic expression of miR-204 in joints triggers spontaneous cartilage loss and OA development, whereas miR-204 inhibition ameliorates experimental OA, with concomitant recovery of PG synthesis and suppression of inflammatory senescence-associated secretory phenotype (SASP) factors in cartilage. Collectively, we unravel a stress-activated senescence pathway that underlies disrupted matrix homeostasis in OA cartilage