Laser-Induced Forward Transfer of Micro spacers for Alignment Correction in PIC Modules

Laser-induced Forward Transfer (LIFT) is an additive manufacturing technique that uses ultra-short laser pulses to transfer material from a donor (carrier) to a receiver. The transfer dynamics can be adjusted depending on the application with micrometer or better resolution which makes it suitable for modifying, repairing, and prototyping micro-devices. In some photonic chip applications, it is necessary to place a small chip into a prefabricated groove on a larger chip, with a required alignment accuracy of approximately 100 nm. Due to limitations in the manufacturing process, or inconsistencies in the height of chips from different suppliers, it is difficult to achieve the requirement in the vertical direction. Therefore, in this project, we attempted to use the LIFT method to locally place prefabricated micro-spacers to compensate for height errors. In this paper, we describe spacer fabrication, LIFT parameter optimization, and preliminary transfer results.