Optofluidic random laser

An active disordered medium able to lase is called a random laser (RL). We demonstrate random lasing due to inherent disorder in a dye circulated structured microfluidic channel. We consistently observe RL modes which are varied by changing the pumping conditions. Potential applications for on-chip sources and sensors are discussed.Comment: 3 pages, 4 figure

Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporating new doped materials in order to realize active optical fibers for constructing lasers and amplifiers

Sol–gel-derived glass-ceramic photorefractive films for photonic structures

Glass photonics are widespread, from everyday objects around us to high-tech specialized devices. Among different technologies, sol–gel synthesis allows for nanoscale materials engineering by exploiting its unique structures, such as transparent glass-ceramics, to tailor optical and electromagnetic properties and to boost photon-management yield. Here, we briefly discuss the state of the technology and show that the choice of the sol–gel as a synthesis method brings the advantage of process versatility regarding materials composition and ease of implementation. In this context, we present tin-dioxide–silica (SnO2–SiO2) glass-ceramic waveguides activated by europium ions (Eu3+). The focus is on the photorefractive properties of this system because its photoluminescence properties have already been discussed in the papers presented in the bibliography. The main findings include the high photosensitivity of sol–gel 25SnO2:75SiO2 glass-ceramic waveguides; the ultraviolet (UV)-induced refractive index change (∆n ~ −1.6 × 10−3), the easy fabrication process, and the low propagation losses (0.5 ± 0.2 dB/cm), that make this glass-ceramic an interesting photonic material for smart optical applications

High-quality-factor dye-doped polymeric microdiscs fabricated by soft imprint lithography

We present a study on the photophysical properties of pyrromethene 570-doped polymethyl methacrylate (PMMA) thin films with varying dye concentrations. The emission and absorption spectra are analyzed to identify the optimum dye concentration in the polymer matrix for efficient light emission. The refractive index and the gain coefficient of pyrromethene 570-doped PMMA thin film was estimated by ellipsometry technique and variable stripe length method, respectively. The fabrication of high optical quality microdiscs is demonstrated by soft imprint lithography technique. Further, the lasing characteristics of the whispering gallery mode (WGM) microdisc resonator are evaluated. The high power density built within these microdisc resonator due to the WGM, combined with the high fluorescence quantum yield of pyrromethene 570 dye in PMMA matrix, gives rise to the lasing threshold pump fluence of $$\sim$$ 37.5 mJ/cm$$^2$$ under nanosecond pulsed excitation. WGMs with a quality factor of $$2.89 \times 10^4$$ were recorded indicating the high morphological and optical quality of the fabricated microdisc

Single-Molecule Cholesterol Sensing by Integrating Silver Nanowire Propagating Plasmons and Graphene Oxide π‑Plasmons on a Photonic Crystal-Coupled Emission Platform

The escalating concern about ohmic losses in metal-dependent plasmonics demands more effective material fabrication for the development of biosensing frameworks. The omnidirectionality and low signal collection efficiency of a conventional fluorescence-based detection platform make it challenging to realize better sensitivity for real-time point-of-care diagnostics. In an attempt to address these demands, recently a photonic crystal-coupled emission (PCCE) platform has been demonstrated to outperform the well-established surface plasmon-coupled emission platform for biophysicochemical sensing applications. The effects of the different numbers of bilayers (BLs) of a one-dimensional photonic crystal (1DPhC) on the electric field intensity of Bloch surface waves and internal optical modes (IOMs) are extensively studied in this work to improve the performance of the PCCE platform rationally. Specifically, the 1DPhC with 10 BLs presented 55-fold PCCE enhancements because of the strong field confinement by the IOMs and small losses. In addition, the critical role of nanoengineering graphene oxide π-plasmon and silver nanowires on the PCCE platform has been explored to yield an unprecedented >1300-fold increase in fluorescence intensity. The amplified PCCE enhancements obtained with the first experimental evidence of the synergism among dielectric plasmons (1DPhC), graphene oxide plasmons, and metal plasmons (from silver nanowires) have been utilized to sense cholesterol at the single-molecule limit of detection. The photoplasmonic sensor presented here exhibits potential utility in academia and industry and provides a perspective for combining materials at nanoregimes for the desired applications