We propose and demonstrate a direct integration of a wavelength-scale III−V nanolaser onto a silicon-on-insulator (SOI) waveguide. By employing high-precision microtransfer printing techniques, with an optimally designed photonic crystal nanolaser structure, we experimentally achieved a coupling efficiency of 83% between the InGaAsP nanobeam laser and the SOI waveguide. Our III−V nanobeam laser is designed as an asymmetric one-dimensional photonic crystal cavity, which allows unidirectional coupling to the combined III−V nanobeam waveguide with high efficiency. Through the compact vertical coupler in the region where the III−V and SOI waveguides overlap at the optimal length of 3.2 μm, 88% of the light from the printed III−V nanolaser can theoretically be coupled to a vertically integrated SOI waveguide.

Global pollution from toxic metal waste has resulted in increased research on toxic metal adsorption. A cellulose acetate–polyurethane (CA–PU) film adsorbent was successfully prepared in this research. The cellulose acetate–polyurethane film adsorbent was prepared with a polycondensation reaction between cellulose acetate and methylene diphenyl diisocyanate. The CA–PU bond formation was confirmed by functional group analysis obtained from Fourier transform infrared (FTIR) spectroscopy. The obtained film was characterized for improved tensile and thermal properties with the addition of methylene diphenyl diisocyanate (MDI). The adsorption ability of the obtained film was evaluated with laser-induced breakdown spectroscopy (LIBS). The best film adsorbent from the LIBS was selected and studied for adsorption isotherm. The FTIR analysis confirmed the formation of the CA–PU bond from the polycondensation between cellulose acetate and the methylene diphenyl diisocyanate. The result showed that the addition of methylene diphenyl diisocyanate (MDI) resulted in the urethane network’s growth. The characterization result showed an improvement in the morphology, thermal stability, and tensile strength of the film. The LIBS studies showed improvement in the adsorption of Pb2+ with CA–PU compared with the neat CA. The isotherm studies revealed that Pb2+ adsorption by cellulose acetate–polyurethane film adsorbent was heterogeneously dependent on the Freundlich isotherm model (R2 = 0.97044). Overall, the polycondensation method proposed by this study enhanced the Pb2+ removal, and was comparable to those reported in previous studies.

Ultralow threshold nanolasers have been sought after as power efficient light sources in photonic integrated circuits. Here a single-cell nanobeam laser with a nanoisland quantum well is proposed and demonstrated. Continuous operation at 1.5 μm is achieved at room temperature with an ultralow lasing threshold of 210 nW in absorbed power. The size of the active medium is reduced to 0.7 × 0.25 × 0.02 μm3 by removing the absorptive quantum well region surrounding the central cavity. Relatively thick (420 nm) InP slabs are employed to improve the thermal and mechanical characteristics. The nanoisland-based structures will provide a new platform to engineer fundamental light–matter interactions by controlling the size and the location of the nanoemitters, allowing the realization of highly efficient nanophotonic devices.

The use of polymeric material in heavy metal removal from wastewater is trending. Heavy metal removal from wastewater of the industrial process is of utmost importance in green/sustainable manufacturing. Production of absorbent materials from a natural source for industrial wastewater has been on the increase. In this research, polyurethane foam (PUF), an adsorbent used by industries to adsorb heavy metal from wastewater, was prepared from a renewable source. Castor oil-based polyurethane foam (COPUF) was produced and modified for improved adsorption performance using fillers, analyzed with laser-induced breakdown spectroscopy (LIBS). The fillers (zeolite, bentonite, and activated carbon) were added to the COPUF matrix allowing the modification on its surface morphology and charge. The materials were characterized using Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and thermal gravimetry analysis (TGA), while their adsorption performance was studied by comparing the LIBS spectra. The bentonite-modified COPUF (B/COPUF) gave the highest value of the normalized Pb I (405.7 nm) line intensity (2.3), followed by zeolite-modified COPUF (Z/COPUF) (1.9), and activated carbon-modified COPUF (AC/COPUF) (0.2), which indicates the adsorption performance of Pb2+ on the respective materials. The heavy metal ions’ adsorption on the B/COPUF dominantly resulted from the electrostatic attraction. This study demonstrated the potential use of B/COPUF in adsorption and LIBS quantitative analysis of aqueous heavy metal ions.