设计了一种包含圆柱形纳米线、空气间隙和半圆顶金属脊结构的低阈值纳米激光器.通过有限元法对激光器的模式特性、品质因数以及增益阈值进行数值计算，并研究了这些特性因子随结构几何参数(空气间隙、金属脊宽度和纳米线半径)的变化情况.结果表明，通过对参数进行调整，激光器的性能得到了显著优化.在最优参数下，增益阈值可达0.47 μm-1，传输损耗仅为0.018.本文设计的纳米激光器能够实现低阈值的亚波长激射和低损耗传输，在生物医学、光通信等领域有广泛的应用前景，可为小型化和集成化的纳米设备提供技术支持.

A low threshold nanolaser that contains nanowires, air gap and semicircular-top metal nanoridge structure was proposed.Through the finite element method to model characteristics and the quality of the laser gain factor and threshold for numerical calculation, the characteristic factor was studied with the geometric parameters (air gap, metal ridge width and nanowire radius) change. The results show that the property of the laser is optimized by adjusting the parameters. Under the optimal parameters, the gain threshold can reach 0.47 μm-1 and the transmission loss is only about 0.018. This shows that the nanolaser structure can achieve low threshold sub wavelength lasing and low loss transmission. It has a wide application prospect in the fields of biomedicine, optical communication etc. It provides technical support for miniaturization and integration of nano devices.