还是相当不错的。
比如这个合作的文章:
Tunable Wavelength Conversion of ps-Pulses Exploiting Cascaded Sum- and Difference Frequency Generation in a PPLN-Fiber Ring Laser, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 18, NO. 20, OCTOBER 15, 2006
http://ieeexplore.ieee.org/iel5/68/35975/01704878.pdf?tp=&isnumber=&arnumber=1704878