Advancing lithium niobate on silicon nitride platform in the visible and the near infrared (NIR), LOLIPOP project

Silicon nitride (SiN) photonic integrated circuits offer low propagation loss, wide optical transparency [1-3], and excellent scalability, but their limited intrinsic electro-optic, nonlinear, and optoelectronic functionality restricts their use in broadband active photonic systems. The LOLIPOP project addresses these limitations through hybrid integration of lithium niobate on insulator (LNOI) thin films and semiconductor devices onto TriPleX SiN circuits, enabling ultra-wideband photonic integrated circuits operating from 400 nm to 1600 nm. The platform combines micro-transfer printing of thin-film LNOI for electro-optic modulation and nonlinear processing [4-7], flip-chip bonding of GaAs external-cavity laser gain elements, and precision edge coupling between heterogeneous photonic chips. Broadband, high-speed Germanium (Ge) photodiodes integrated within the SiN platform provide optical detection across all wavelength regimes of interest [8-9]. The capabilities of the hybrid platform are demonstrated through representative subsystems including laser Doppler vibrometry, LiDAR, neuromorphic photonic processors, and squeezed-state generation for continuous-variable quantum applications. This paper presents the integration architecture, key design considerations, and fabrication and packaging challenges, establishing a scalable hybrid SiN platform for advanced broadband photonic systems