Large-Area Biocompatible Random Laser for Wearable Applications

Abstract

Recently, wearable sensor technology has drawn attention to many health-related appliances due to its varied existing optical, electrical, and mechanical applications. Similarly, we have designed a simple and cheap lift-off fabrication technique for the realization of large-area biocompatible random lasers to customize wearable sensors. A large-area random microcavity comprises a matrix element polymethyl methacrylate (PMMA) in which rhodamine B (RhB, which acts as a gain medium) and gold nanorods (Au NRs, which offer plasmonic feedback) are incorporated via a spin-coating technique. In regards to the respective random lasing device residing on a heterogenous film (area > 100 cm2), upon optical excitation, coherent random lasing with a narrow linewidth (~0.4 nm) at a low threshold (~23 μJ/cm2 per pulse) was successfully attained. Here, we maneuvered the mechanical flexibility of the device to modify the spacing between the feedback agents (Au NRs), which tuned the average wavelength from 612.6 to 624 nm under bending while being a recoverable process. Moreover, the flexible film can potentially be used on human skin such as the finger to serve as a motion and relative-humidity sensor. This work demonstrates a designable and simple method to fabricate a large-area biocompatible random laser for wearable sensing.

Random laser emission from dye-doped polymer films enhanced by SiC nanowires

“…The central lasing wavelength appears a significant blue shift from ∼655 nm to ∼641 nm with the SiC concentration increasing from 0.02 mg ml −1 to 4 mg ml −1 at the same excitation conditions and dye concentration, shown in figure 8. While the concentration increases, the distance among the SiC decreases obviously, which brings the decrease of the scattering mean free path, resulting in a blue shift of the emission wavelength [53][54][55]. Here, the wavelength is tuned to 14 nm by the scatterer concentration, which is beneficial for the modulation of random lasers.…”

Synthesis and Characterization of Silver-Gold Bimetallic Nanoparticles for Random Lasing

“…Besides that, the surface plasmon resonance frequency was able to be tuned to the desired spectral range by varying the thickness of the outer metal shell, the thickness and dielectric constant of the intermediate dielectric medium, the geometric shape, and the aspect ratio of the three-layered bimetallic nanoparticles [13]. Random lasing is greatly influenced by the overlapping of surface plasmon resonance of metallic nanoparticles and the emission spectrum of the dye medium [13,14]. This situation does not only increase the dye excitation and energy transfer, but also affect the dye emission, leading to local field enhancement [13][14][15].…”

“…Random lasing is greatly influenced by the overlapping of surface plasmon resonance of metallic nanoparticles and the emission spectrum of the dye medium [13,14]. This situation does not only increase the dye excitation and energy transfer, but also affect the dye emission, leading to local field enhancement [13][14][15]. Thus, overlapping of these elements can influence the properties of random lasing.…”

An all-optical tunable polymer WGM laser pumped by a laser diode

“…Polymer lasers, owing to their advantage of a large wavelength tuning range, 1 have become an important category of tunable laser sources over the whole visible spectrum, and have been applied in sensing [2][3][4][5] and full color laser displays. [6][7][8][9][10] The polymer materials possess the advantages of easy processing and low cost, which make them ideal gain media for lasers. In recent years, various geometries of polymer lasers have received signicant attention, such as Fabry-Perot structures, 11 distributed feedback structures, [12][13][14] photonic crystals, 15,16 and whispering-gallery-mode (WGM) cavities.…”