Recent advancements in photonic-electronic integration push towards denser multichannel fiber to silicon photonic chip coupling solutions. However, current packaging schemes based on suitably polished fiber arrays do not provide sufficient scalability. Alternatively, lithographically-patterned fused silica glass interposers have been proposed, allowing for the integration of fanout waveguides between a dense array of on-chip silicon waveguides and a cleaved fiber ribbon. In this paper, we propose the use of femtosecond laser inscription for the fabrication of the fused silica glass interposer, allowing for a monolithic integration of waveguides and V-grooves for fiber alignment. The waveguides obtained by Femtosecond Laser Direct Writing (FLDW) have a propagation loss of 0.88 dB/cm at 1550 nm. The mode-field diameter is 12.8 $\pm$ 0.4 $\mu$ m, allowing for a coupling loss of 1.24 $\pm$ 0.32 dB when coupling to a standard single mode optical fiber, passively aligned to the fused silica waveguide by insertion in a V-groove created by Femtosecond Laser Irradiation followed by Chemical Etching (FLICE). The average surface roughness of the etched waveguide facet is 160 $\pm$ 5 nm. Scattering loss when coupling to fiber is reduced by use of an index-matching adhesive for fiber fixation. A polished out-of-plane coupling mirror at an angle of 41.5 $^{\circ }$ injects the light into standard grating couplers, providing a quasi-planar fiber-to-chip package. The excess loss of the proposed solution is limited to 2 dB per interface, including mirror, waveguide and fiber coupling losses.

中文翻译：

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激光写入玻璃中介层，用于光纤耦合到硅光子集成电路

光电子集成的最新进展推动了更密集的多通道光纤到硅光子芯片耦合解决方案的发展。然而，基于适当抛光的纤维阵列的当前包装方案不能提供足够的可扩展性。可替代地，已经提出了光刻图案化的熔融石英玻璃插入物，其允许在密集的片上硅波导阵列和分裂的光纤带之间集成扇出波导。在本文中，我们建议使用飞秒激光铭文来制造熔融石英玻璃中介层，以实现波导和V形槽的单片集成以进行光纤对准。通过飞秒激光直接写入（FLDW）获得的波导在1550 nm处的传播损耗为0.88 dB / cm。模场直径为12.8$ \ pm $ 0.4 $ \ mu $ m，耦合损耗为1.24 $ \ pm $当耦合到标准单模光纤时为0.32 dB，通过插入飞秒激光辐照和化学蚀刻（FLICE）产生的V形槽，被动地对准熔融石英波导。蚀刻的波导小平面的平均表面粗糙度为160$ \ pm $5纳米 通过使用折射率匹配粘合剂固定光纤，可以减少与光纤耦合时的散射损失。抛光的平面外耦合镜，角度为41.5 $ ^ {\ circ} $将光注入标准光栅耦合器，提供准平面的光纤到芯片封装。提出的解决方案的额外损耗限制为每个接口2 dB，包括反射镜，波导和光纤耦合损耗。