排序方式: 共有19条查询结果,搜索用时 31 毫秒
1.
We report a simple Nd:YAG laser that emits radially polarized beam with helical wavefront. The laser cavity consists of a piece of laser crystal and a plane output coupler, and there is no additional polarization component inside it. The pump light is converted into annular profile through de-focal coupling into a multi-mode fiber. For the continuous-wave(CW) operation, the laser emits radially polarized vortex beam, and it is observed that the helical wavefront of the laser beam is switched from right handedness to left handedness when the output coupler is tilted slightly. For the Q-switched operation under the insertion of a Cr4t:YAG saturable absorber inside the cavity, we obtain radially polarized outputs with left-handedness helical wavefront. By tilting the laser crystal slightly, the laser output switches to azimuthal polarization at pump power larger than 4.5 W and left-handedness helical wavefront of laser beam is preserved. 相似文献
2.
We report on a radially polarized and passively Q-switched Nd:YAG/Cr4+:YAG laser.The bulk Nd:YAG crystal is bonded with two undoped YAG crystal end caps to weaken the thermal lens e?ect and thus,enhance the extraction of stored energy in the bulk gain material.In the absence of active water cooling,the average laser power reaches 383 mW with 33% slope efficiency,and the laser pulse achieves 1.457-W peak power,18.9-ns duration,and 13.9-kHz repetition rate with 97.6% polarization purity. 相似文献
3.
4.
光折变全息记录和二波耦合过程都是动力学光栅过程 ,二光束的干涉光强通过激发电子而产生感应相位栅与此相位栅通过光波耦合改变光束的相对强度的这两个过程同时发生 .以干涉光强调制度为主要变量 ,对于联立的带传输方程和耦合波方程 ,求得了适用于任意的干涉光强调制度下的解析解 ,其中考虑了电子的扩散、漂移、光生伏打效应 ,并且以不同的光激发效率作为初始条件 .此解比原来的不考虑光束耦合的全息记录或不考虑非线性响应的光束耦合更精确 .计算表明 ,对比于线性近似下的典型二波耦合 ,动态光栅的调制度在晶体内的空间变化更为缓慢 . 相似文献
5.
6.
以Fe:LiNbO3晶体为例,考虑了电子载流子热激发(强烈地依靠于温度),通过对以扩散和光伏特效应为主导输运机制的带输运议程和耦合波方程进行数值求解,分析了热固定过程初始光强入射比和固定温度对光栅空间电荷场的影响,指出记录固定过程中内电场极值的出现为源于质子电场对施主光栅电场的部分补偿,质子光栅电荷场可以导致晶体中记录光束之间能量耦合方向的变化,得出了理论上的加热固定时间。 相似文献
7.
8.
9.
A method on amplitude-weighted array technology is proposed based on an analytical formula in which the radiation amplitudes of array elements are evaluated analytically by a random symmetrical far-field radiation pattern. Using this formula, any desired spatial radiation pattern in the far field could be built by applying the analytical solutions of radiation amplitudes of array elements. To check the validity of this formula as well as the proposed technique, an annular intensity distribution as target far-field pattern is designed, and the respective radiation amplitude of array elements are determined by solving the formula analytically. The available far-field pattern is calculated by applying these solutions and then compared with the target far-field pattern. The theoretical results show the capabilities of the analytical derivation as well as the proposed techniaue in formin~ specific radiation Patterns. 相似文献
10.
We demonstrate an end-pumped,c-cut Nd:YVO4 laser that emitted first-order Laguerre-Gaussian(LG01) beam by adjusting the position of focused pump beam relative to laser crystal.The pumping light reached the laser crystal has circular and solid intensity profile.The laser is compact and stable,and the obtained LG01 beam power reaches 202 mW with ~25% slope efficiency. 相似文献