Large nonlinear phase shifts were generated with femtosecond pulses at 1560 nm through cascaded quadratic interactions in periodically poled MgO-doped LiNbO<sub>3</sub> . The off-diagonal component of the nonlinear coefficient was utilized for simultaneous quasi phase matching and group-velocity matching. The effective nonlinear refractive index was varied from -2.9×10<sup>-14</sup> to +3.3×10<sup>-14</sup>cm <sup>2</sup>/W by tuning the phase-mismatch conditions.
© 2003 Optical Society of America
(160.3730) Materials : Lithium niobate
(190.2620) Nonlinear optics : Harmonic generation and mixing
(190.5940) Nonlinear optics : Self-action effects
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
Satoshi Ashihara, Tsutomu Shimura, Kazuo Kuroda, Nan Ei Yu, Sunao Kurimura, Kenji Kitamura, Jung Hoon Ro, Myoungsik Cha, and Takunori Taira, "Group-velocity-matched cascaded quadratic nonlinearities of femtosecond pulses in periodically poled MgO:LiNbO3," Opt. Lett. 28, 1442-1444 (2003)