Exploring Heterogeneous Integration of Thick Micro-Lens Array for Pluggable Photonics Packaging

Scalability of photonic systems-in-package assembly remains one of the critical areas that needs to be addressed in the era of artificial intelligence (AI). Traditional optical packaging involves individual fibre or micro-optics to photonic integrated circuit (PIC) assembly. This process can be labour-intensive and time consuming due to active alignment requirements. Micro-transfer printing (µTP) technology can solve the scalability challenge by enabling volume integration of photonic devices. Instead of tether approach used in traditional µTP for integrating non-native materials and thin components (≤ 4 µm) such as lasers, modulators and micro-LEDs that are limited to certain thicknesses usually up to 1-2µm, we used tether-less approach and successfully transfer printed thick microlens arrays (500-1000 µm) onto optical couplers on PIC with good alignment accuracy. To evaluate the optical compatibility of tether-less µTP approach, the optically pluggable packaging prototype was built, boasting high 1dB tolerance (up to ±20 µm in x and y directions) and low insertion loss (- 3.55 dB). Notably, the prototype achieves very good reproducibility in pluggable connections, with a variation of only - 0.05 dB. Additionally, the potential of tether-free µTP for enabling large-scale parallel integration of thick components in photonics packaging applications was explored. This research overcomes existing limitations in optical packaging through scalable solutions and sets the stage for future advancements in high-performance data communication systems.