Mangal Nivesh, Snyder Bradley, Van Campenhout Joris, Van Steenberge Geert, Missinne Jeroen
Opt Express. 2021 Mar 1;29(5):7601-7615. doi: 10.1364/OE.412353.
To increase the manufacturing throughput and lower the cost of silicon photonics packaging, an alignment tolerant approach is required to simplify the process of fiber-to-chip coupling. Here, we demonstrate an alignment-tolerant expanded beam backside coupling interface (in the O-band) for silicon photonics by monolithically integrating microlenses on the backside of the chip. After expanding the diffracted optical beam from a TE-mode grating through the bulk silicon substrate, the beam is collimated with the aid of microlenses resulting in an increased coupling tolerance to lateral and longitudinal misalignment. With an expanded beam diameter of 32 μm, a ±7 μm lateral and a ±0.6 angular fiber-to-microlens 1-dB alignment tolerance is demonstrated at the wavelength of 1310 nm. Also, a large 300 μm longitudinal alignment tolerance with a 0.2 dB drop in coupling efficiency is obtained when the collimated beam from the microlens is coupled into a thermally expanded core single-mode fiber.
为了提高硅光子学封装的制造产量并降低成本，需要一种容忍对准误差的方法来简化光纤与芯片耦合的过程。在此，我们通过在芯片背面单片集成微透镜，展示了一种用于硅光子学的（在O波段）容忍对准误差的扩束背面耦合接口。从TE模式光栅衍射出的光束穿过体硅衬底后扩展，借助微透镜使光束准直，从而提高了对横向和纵向对准误差的耦合容忍度。在1310 nm波长下，扩束光束直径为32μm时，光纤与微透镜的横向对准容忍度为±7μm，角度对准容忍度为±0.6°，1 dB带宽内耦合效率保持稳定。此外，当微透镜准直后的光束耦合到热膨胀芯单模光纤中时，纵向对准容忍度高达300μm，耦合效率下降0.2 dB。
