PhD Public Defense
Fiber to Chip Fusion Splicing for Low Loss Optical Coupling
Supervised by Jaime Cardenas
Wednesday, March 1, 2023
10 a.m.11 a.m.
202 Humanities Center - Conference Room D
Integrated photonic devices are poised to enter high volume markets such as data communications, optical phased arrays, and telecommunications; however, permanently attaching an optical fiber to a photonic chip with high optical efficiency and low cost still remains a challenge [1–4].
During the past few decades, the basic building blocks of silicon photonic devices have been demonstrated: modulators, detectors, switches, filters, and lasers. One of the remaining challenges is to develop a packaging method to permanently attach optical fibers to photonic chips with high optical efficiency and high speed, while maintaining compatibility with CMOS processing without introducing changes to the fabrication process or consuming a significant area on the chip.
Multiple methods have been demonstrated to increase the coupling efficiency between an optical fiber and a chip while simultaneously decreasing packaging costs and increasing throughput for high volume manufacturing. However, current coupling methods are lossy, bandwidth limited or involve complex fabrication steps. [1, 5–47]
We present a low-cost, robust, and low-loss packaging technique of permanent optical edge coupling between a fiber and multiple fiber to a chip using fusion splicing that is scalable for high-volume manufacturing and has a larger alignment tolerance. We fusion splice a cleaved optical fiber and/or optical fiber array to an oxide mode converter  at the edge of the chip. The oxide mode converter helps in improving the losses and acts as an interface for fiber attachment. The oxide mode converters are fabricated using photo-lithography and are isolated from the silicon substrate to prevent op- tical loss to the substrate. We characterize the losses along the chip and the fiber for the c-band wavelength and attach single fibers, multiple fibers, as well as, specialty fibers to the photonic device.
We envision that this method can be fully automated to enable highly efficient fiber to chip coupling in high volume applications. This will help pave a path to low-loss, low-cost optical packaging of integrated photonic devices.