Yu Nan Ei, Ro Jung Hoon, Cha Myoungsik, Kurimura Sunao, Taira Takunori
Opt Lett. 2002 Jun 15;27(12):1046-8. doi: 10.1364/ol.27.001046.
A novel scheme for broadband second-harmonic generation was developed with type I quasi phase matching by use of an off-digital nonlinear optical coefficient d(31) . This was achieved by matching of the group velocities of the second harmonic and the fundamental, while the phase velocities were quasi phase matched. The desired group-velocity dispersion could be obtained with LiNbO(3) doped with 5 mol. % of MgO. Efficient second-harmonic generation with a bandwidth of 52 nm was obtained for the fundamental wavelength centered at 1566 nm in MgO-doped periodically poled LiNbO(3) , compared with a bandwidth of 1.3 nm for the conventional scheme using d(33) . Efficient frequency doubling of an ultrafast pulse is expected without group-velocity walk-off or pulse distortion.
利用非数字非线性光学系数d(31)，通过I型准相位匹配开发了一种用于宽带二次谐波产生的新颖方案。这是通过匹配二次谐波和基波的群速度来实现的，而相速度则是准相位匹配的。掺杂5摩尔%氧化镁的铌酸锂（LiNbO₃）可以获得所需的群速度色散。对于以1566 nm为中心波长的基波，在掺杂氧化镁的周期性极化铌酸锂中获得了带宽为52 nm的高效二次谐波产生，相比之下，使用d(33)的传统方案带宽为1.3 nm。预计超快脉冲能够实现高效倍频，且不存在群速度走离或脉冲失真。
