Second harmonic generation of ultrashort pulses in refractive-index-linear-modulating nonlinear crystals

Broadband and efficient second harmonic generation in LiNbO3-LiTaO3 composite ridge waveguides at telecom-band

“…Meanwhile, broad frequency conversion bandwidth is also highly desirable in many applications such as ultrafast optical signal processing, frequency tunable lasers, and optical telecommunications. [10][11][12] However, due to the groupvelocity mismatching between interaction waves, acceptance bandwidth of highly efficient PPLN frequency conversion process is generally narrow, typically ∼50 GHz (∼0.4 nm), [13] which limits its applications in ultra-shortpulse compression, [14] frequency tunable lasers [15] and optical telecommunications. [16] Several approaches have been demonstrated to broaden the acceptance bandwidth of SHG, including aperiodic domain inverted gratings [17,18] and chirping periodically poled crystals.…”