Micro-cavity laser of dye moleceles loaded in AIPO₄-5 crystals

Micro-cavity laser has attracted extensive attentions due to its potential applications in high-speed integrated opto-electronic device and system. In micro-cavity, spontaneous emission process is enhanced or prohibited, and lasing can occur without a visible threshold. In the past, micro-cavity was realized with semiconductors such as microdisks or vertical cavity surface emitting lasers, with organic dyes embedded in planar resonators as Langmuir-Blodgett films or in spheres, and with gain medium in photonic crystals. In this article, we report a new type of micro-cavity laser based on organic dye molecules incorporated in the channels of AlPO₄-5 single crystals by physical diffusion method. The optical measurements reveal that the dipole transition moment of the enclosed organic dye molecules is highly oriented in the channels. Due to size confinement of the AlPO₄-5 channels, there is a structure deformation of the dye molecules, which leads to a large blue shift in the absorption spectra for the dye/A1PO₄-5 crystal. The micro-sized hexagonal AlPO₄-5 single crystal serves as a good natural micro-cavity for the lasing action of the adsorbed dye molecules. The micro-cavity mode of the lasing action is demonstrated

Rice paddy soils are a quantitatively important carbon store according to a global synthesis

Rice paddies account for similar to 9% or the world's cropland area and are characterized by environmental conditions promoting soil organic carbon storage, methane emissions and to a lesser extent nitrous oxide emissions. Here, we synthesize data from 612 sites across 51 countries to estimate global carbon stocks in paddy soils and determine the main factors affecting paddy soil carbon storage. Paddy soils (0-100 cm) contain 18 Pg carbon worldwide. Paddy soil carbon stocks decrease with increasing mean annual temperature and soil pH, whereas mean annual precipitation and clay content had minor impacts. Meta-analysis shows that paddy soil carbon stocks can be increased through several management practices. However, greenhouse gas mitigation through paddy soil carbon storage is generally outweighed by increases in methane and nitrous oxide emissions. Our results emphasize the key role of paddies in the global carbon cycle, and the importance of paddy management in minimizing anthropogenic greenhouse gas emissions