Chen Baoqin, Hong Lihong, Hu Chenyang, Li Zhiyuan
School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510641, China.
Guangdong Jingqi Laser Technology Corporation Limited, Songshanhu, Dongguan 523808, China.
Research (Wash D C). 2021 Mar 23;2021:1539730. doi: 10.34133/2021/1539730. eCollection 2021.
White laser with balanced performance of broad bandwidth, high average and peak power, large pulse energy, high spatial and temporal coherence, controllable spectrum profile, and overall chroma are highly desirable in various fields of modern science. Here, for the first time, we report an innovative scheme of harnessing the synergic action of both the second-order nonlinearity (2-NL) and the third-order nonlinearity (3-NL) in a single chirped periodically poled lithium niobate (CPPLN) nonlinear photonic crystal driven by a high-peak-power near-infrared (NIR) (central wavelength1400 nm, energy100 J per pulse) femtosecond pump laser to produce visible to near infrared (vis-NIR, 400-900 nm) supercontinuum white laser. The CPPLN involves a series of reciprocal-lattice bands that can be exploited to support quasiphase matching for simultaneous broadband second- and third-harmonic generations (SHG and THG) with considerable conversion efficiency. Due to the remarkable 3-NL which is due to the high energy density of the pump, SHG and THG laser pulses will induce significant spectral broadening in them and eventually generate bright vis-NIR white laser with high conversion efficiency up to 30%. Moreover, the spectral profile and overall chroma of output white laser can be widely modulated by adjusting the pump laser intensity, wavelength, and polarization. Our work indicates that one can deeply engineer the synergic and collective action of 2-NL and 3-NL in nonlinear crystals to accomplish high peak power, ultrabroadband vis-NIR white laser and hopefully realize the even greater but much more challenging dream of ultraviolet-visible-infrared full-spectrum laser.
具有宽带宽、高平均功率和峰值功率、大脉冲能量、高空间和时间相干性、可控光谱轮廓以及整体色度等平衡性能的白色激光在现代科学的各个领域都非常受欢迎。在此，我们首次报道了一种创新方案，利用单个啁啾周期极化铌酸锂（CPPLN）非线性光子晶体中二阶非线性（2-NL）和三阶非线性（3-NL）的协同作用，由高峰值功率近红外（NIR）（中心波长1400 nm，每脉冲能量100 J）飞秒泵浦激光驱动，产生可见到近红外（vis-NIR，400 - 900 nm）超连续谱白色激光。CPPLN包含一系列倒易晶格带，可用于支持准相位匹配，以实现具有相当转换效率的同时宽带二次和三次谐波产生（SHG和THG）。由于泵浦的高能量密度导致显著的3-NL，SHG和THG激光脉冲将在其中引起显著的光谱展宽，并最终产生转换效率高达30%的明亮vis-NIR白色激光。此外，通过调节泵浦激光强度、波长和偏振，可以广泛调制输出白色激光的光谱轮廓和整体色度。我们的工作表明，人们可以深入设计非线性晶体中2-NL和3-NL的协同和集体作用，以实现高峰值功率、超宽带vis-NIR白色激光，并有望实现更宏大但更具挑战性的紫外-可见-红外全光谱激光的梦想。
