Synergy between plasmonic nanocavities and random lasing modes: a tool to dequench plasmon quenched fluorophore emission.

Metal nanoparticles (NPs) can be employed to modify the emission level of a dye emitter by tailoring the spectral overlap of the optical gain and localized surface plasmon resonance (LSPR). In the case of plasmonic random lasers, tuning the spectral overlap by manipulating metal NPs changes the scattering properties of the system, which is crucial in random lasers (RLs). In order to overcome this drawback, the emitter gain spectrum across the LSPR is tuned by appropriately choosing various dye emitters.

Plasmonic Silver Nanoparticle-Mediated Enhanced Broadband Photoresponse of Few-Layer Phosphorene/Si Vertical Heterojunctions.

We report the superior broadband photodetection characteristics of few-layer phosphorene known as black phosphorus (BP) nanosheets integrated with silver nanoparticles (Ag NPs) using vertical heterojunctions on a Si platform. The exfoliation of BP nanosheets and preparation of an Ag NP:BP (Ag-BP) hybrid have been accomplished through environment-friendly and cost-effective chemical routes. The hybrid sample exhibits broadband light absorption with a strong plasmonic peak around ∼425 nm due to the localized surface plasmon resonance (LSPR) of Ag NPs of average size ∼6.

Superior Resonant Nanocavities Engineering on the Photonic Crystal-Coupled Emission Platform for the Detection of Femtomolar Iodide and Zeptomolar Cortisol.

Although luminescence spectroscopy has been a promising sensing technology with widespread applications in point-of-care diagnostics and chem-bio detection, it fundamentally suffers from low signal collection efficiency, considerable background noise, poor photostability, and intrinsic omnidirectional emission properties. In this regard, surface plasmon-coupled emission, a versatile plasmon-enhanced detection platform with >50% signal collection efficiency, high directionality, and polarization has previously been explored to amplify the limit of detection of desired analytes. However, high Ohmic loss in metal-dependent plasmonic platforms has remained an inevitable challenge.

Effect of structural evolution of ZnO/HfO nanocrystals on Eu/Eu emission in glass-ceramic waveguides for photonic applications.

Eu-doped 70SiO-23HfO-7ZnO (mol%) glass-ceramic waveguides have been fabricated by sol-gel method as a function of heat-treatment temperatures for on-chip blue-light emitting source applications. Structural evolution of spherical ZnO and spherical as well as rod-like HfO nanocrystalline structures have been observed with heat-treatments at different temperatures. Initially, in the as-prepared samples at 900 C, both, Eu as well as Eu ions are found to be present in the ternary matrix.

Optofluidic two-dimensional grating volume refractive index sensor.

We present an optofluidic reservoir with a two-dimensional grating for a lab-on-a-chip volume refractive index sensor. The observed diffraction pattern from the device resembles the analytically obtained fringe pattern. The change in the diffraction pattern has been monitored in the far-field for fluids with different refractive indices.

Eu-doped ZnO-HfO2 hybrid nanocrystal-embedded low-loss glass-ceramic waveguides.

We report on the sol-gel fabrication, using a dip-coating technique, of low-loss Eu-doped 70SiO2 -[Formula: see text] HfO2-xZnO (x = 2, 5, 7 and 10 mol%) ternary glass-ceramic planar waveguides. Transmission electron microscopy and grazing incident x-ray diffraction experiments confirm the controlled growth of hybrid nanocrystals with an average size of 3 nm-25 nm, composed of ZnO encapsulated by a thin layer of nanocrystalline HfO2, with an increase of ZnO concentration from x = 2 mol% to 10 mol%  in the SiO2-HfO2 composite matrix. The effect of crystallization on the local environment of Eu ions, doped in the ZnO-HfO2 hybrid nanocrystal-embedded glass-ceramic matrix, is studied using photoluminescence spectra, wherein an intense mixed-valence state (divalent as well as trivalent) emission of Eu ions is observed.

Mono- to few-layered graphene oxide embedded randomness assisted microcavity amplified spontaneous emission source.

The realization of optoelectronic devices using two-dimensional materials such as graphene and its intermediate product graphene oxide (GO) is extremely challenging owing to the zero band gap of the former. Here, a novel amplified spontaneous emission (ASE) system based on a GO-embedded all-dielectric one-dimensional photonic crystal (1DPhC) micro-resonator is presented. The mono- to few-layered GO sheet is inserted within a microcavity formed by two 5-bilayered SiO2/SnO2 Bragg reflectors.

Signatures of periodicity and randomness in the angular emission profile of a 2-D on-average periodic optofluidic random laser.

Angle-dependent emission from a dye infiltrated 2-D on-average periodic structured optofluidic random laser is studied. Distinct signatures of periodicity and randomness are observed in the angle-resolved emission spectra of the device. Emission patterns composed of concentric ellipses are observed on transverse excitation of the device, attributed to the in-plane diffraction of light by a 2-D square lattice.