Zhang Yuxia, Yu Haohai, Zhang Huaijin, Xu Xiaodong, Xu Jun, Wang Jiyang
Opt Express. 2016 Mar 7;24(5):5514-5522. doi: 10.1364/OE.24.005514.
A light beam with a helical phase is associated with an optical vortex and carries optical orbital angular momentum. Mode-locked optical vortex pulses impart orbital angular momentum to photons in short pulses and have attractive applications. However, due to the conflict between mature mode-locking and the generation of optical vortices, directly generated mode-locked optical vortex short pulses seem to be unavailable, thus constraining the development and applications of optical vortex short pulses. Laguerre-Gaussian (LG) modes are eigenfunctions for a laser cavity. Besides carrying optical orbital angular momentum, LG beams also have self-healing and quasi-nondiffracting properties. Here, we report the realization of a self-mode-locked LG lasers with tunable orbital angular momentum. By coupling between the thermal and optical fields, the orbital angular momentum was found to be staged. These results verify the possibility of direct mode-locking of optical vortices, and may open the way for several applications of short pulses. Moreover, mode-locked pulses with high-repetition rates also have particularly attractive applications such as optical frequency comb spectroscopy, high capacity optical networks, spectroscopy of metallic nanoparticles, arbitrary waveform generation, etc..
具有螺旋相位的光束与光学涡旋相关联，并携带光学轨道角动量。锁模光学涡旋脉冲在短脉冲中赋予光子轨道角动量，具有吸引人的应用。然而，由于成熟的锁模技术与光学涡旋的产生之间存在冲突，直接产生锁模光学涡旋短脉冲似乎是不可行的，从而限制了光学涡旋短脉冲的发展和应用。拉盖尔 - 高斯（LG）模式是激光腔的本征函数。除了携带光学轨道角动量外，LG光束还具有自愈合和准无衍射特性。在此，我们报告了实现具有可调轨道角动量的自锁模LG激光器。通过热场和光场之间的耦合，发现轨道角动量是分级的。这些结果验证了光学涡旋直接锁模的可能性，并可能为短脉冲的多种应用开辟道路。此外，具有高重复率的锁模脉冲还具有特别吸引人的应用，如光学频率梳光谱学、高容量光网络、金属纳米颗粒光谱学、任意波形产生等。
