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This study examines the lasing performance of optically pumped wurtzite‐phase InP nanowire (NW) photonic crystal surface‐emitting lasers (PCSELs) with the goal of optimizing the cavity design for low‐threshold lasing. By varying the photonic crystal lattice constant and NW diameter, this study systematically investigates the threshold power and the threshold gain. Using finite‐difference time‐domain simulations and gain spectra modeling, this study finds that the lowest pump threshold occurs when the cavity resonance energy is slightly above the spontaneous emission maximum energy due to high differential gain. Furthermore, PCSEL structures with an apothem‐to‐pitch ratio of ≈0.15 are advantageous because they provide increased confinement factors, resulting in the lowest lasing threshold and high laser output. This study paves the path toward low‐threshold NW PCSEL designs for photonic integrated circuits. 

Permeable sediments, which make up almost half of the continental shelf worldwide, are potential sources of the important greenhouse gas N2O from coastal regions. Yet, the extent to which interactions between these sediments and anthropogenic pollution produce N2O is still unknown. Here we use laboratory experiments and modeling to explore the factors controlling N2O production at a eutrophic site in a temperate shallow marine embayment (Port Phillip Bay, Australia). Our results show that denitrification is the main source of N2O production within permeable sediments, but the extent to which N2O is actually released is determined by the rate of seawater exchange with the sediment bed (which governs solute residence time within the bed). In wave‐dominated coastal areas, shallower water with more intense waves (wave height >> 1 m) release the most N2O, with up to 0.5% of dissolved inorganic nitrogen pumped into biologically active eutrophic sediment being released as N2O. Our results suggest rates of N2O production in coastal permeable sediments are generally low compared to other environments.