Optical waveguides made from periodically poled materials provide high confinement of light and enable the generation of new wavelengths via quasi-phase-matching, making them a key platform for nonlinear optics and photonics. However, such devices are not typically employed for high-harmonic generation. Here, using 200-fs, 10-nJ-level pulses of 4100-nm light at 1 MHz, we generate high harmonics up to the 13th harmonic (315 nm) in a chirped, periodically poled lithium niobate waveguide. Total conversion efficiencies into the visible–ultraviolet region are as high as 10%. We find that the output spectrum depends on the waveguide poling period, indicating that quasi-phase-matching plays a significant role. In the future, such periodically poled waveguides may enable compact sources of ultrashort pulses at high repetition rates and provide new methods of probing the electronic structure of solid-state materials.

中文翻译：

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周期性极化波导中的高谐波产生

由周期性极化的材料制成的光波导提供了较高的光限制，并通过准相位匹配能够产生新的波长，从而使其成为非线性光学和光子学的关键平台。但是，这种设备通常不用于高谐波产生。在这里，使用200 fs，10 nJ级别的1100 MHz的4100 nm光脉冲，我们会在，形，周期性极化的铌酸锂波导中产生高达13次谐波（315 nm）的高谐波。可见-紫外线区域的总转换效率高达10％。我们发现输出频谱取决于波导极化周期，这表明准相位匹配起着重要的作用。将来，