Femtosecond laser writing is a powerful technique that allows rapid and cost‐effective fabrication of photonic integrated circuits with unique 3D geometries. In particular, the possibility to reconfigure such devices by thermo‐optic phase shifters represents a paramount feature, exploited to produce adaptive and programmable circuits. However, the scalability is strongly limited by the flaws of current thermal phase shifters, which require hundreds of milliwatts to operate and exhibit large thermal crosstalk. In this work, thermally‐insulating 3D microstructures are exploited to decrease the power needed to induce a 2π phase shift down to 37 mW and to reduce the crosstalk to a few percent. Further improvement is demonstrated when operating in vacuum, with sub‐milliwatt power dissipation and negligible crosstalk. These results pave the way toward the demonstration of complex programmable integrated photonic circuits fabricated by femtosecond laser writing, thus opening exciting perspectives in integrated quantum photonics.

中文翻译：

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飞秒激光微加工制造的集成光子电路中的低功率可重构性和降低的串扰

飞秒激光写入是一项强大的技术，可以快速且经济高效地制造具有独特3D几何形状的光子集成电路。特别是，通过热光移相器重新配置此类设备的可能性是最重要的功能，可用于生产自适应和可编程电路。但是，可扩展性受到当前热移相器的缺陷的严重限制，该缺陷需要数百毫瓦才能工作并表现出较大的热串扰。在这项工作中，利用隔热的3D微结构来降低将2π相移降低到37 mW所需的功率，并将串扰降低到几个百分点。在真空中运行时，具有小于数毫瓦的功耗和可忽略不计的串扰，显示出了进一步的改进。