Billat Adrien, Grassani Davide, Pfeiffer Martin H P, Kharitonov Svyatoslav, Kippenberg Tobias J, Brès Camille-Sophie
Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland, Photonic Systems Laboratory (PHOSL), STI-IEL, Station 11, CH-1015, Lausanne, Switzerland.
Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland, Laboratory of Photonics and Quantum Measurements (LPQM), SB-IPHYS, Station 3, CH-1015, Lausanne, Switzerland.
Nat Commun. 2017 Oct 18;8(1):1016. doi: 10.1038/s41467-017-01110-5.
Efficient second harmonic generation in integrated platforms is usually achieved by resonant structures, intermodal phase-matching or quasi-phase matching by periodically poling ferroelectric waveguides. However, in all these structures, it is impossible to reconfigure the phase-matching condition in an all-optical way. Here, we demonstrate that a Watt-level laser causes a periodic modification of the second-order susceptibility in a silicon nitride waveguide, allowing for quasi-phase-matching between the pump and second harmonic modes for arbitrary wavelengths inside the erbium band. The grating is long-term inscribed, and leads to a second harmonic generation enhancement of more than 30 dB. We estimate a χ on the order of 0.3 pm/V, with a maximum conversion efficiency of 0.05% W. We explain the observed phenomenon with the coherent photogalvanic effect model, which correctly agrees with the retrieved experimental parameters.
集成平台中的高效二次谐波产生通常通过谐振结构、模式间相位匹配或通过周期性极化铁电波导实现的准相位匹配来实现。然而，在所有这些结构中，不可能以全光方式重新配置相位匹配条件。在此，我们证明瓦级激光会导致氮化硅波导中二阶极化率的周期性变化，从而允许在铒波段内的任意波长下泵浦模式和二次谐波模式之间实现准相位匹配。该光栅是长期写入的，并导致二次谐波产生增强超过30 dB。我们估计χ约为0.3 pm/V，最大转换效率为0.05%/W。我们用相干光电流效应模型解释了观察到的现象，该模型与检索到的实验参数正确吻合。
