In this article we describe a cost-effective approach for hybrid laser integration, in which vertical cavity surface emitting lasers (VCSELs) are passively-aligned and flip-chip bonded to a Si photonic integrated circuit (PIC), with a tilt-angle optimized for optical-insertion into standard grating-couplers. A tilt-angle of 10° is achieved by controlling the reflow of the solder ball deposition used for the electrical-contacting and mechanical-bonding of the VCSEL to the PIC. After flip-chip integration, the VCSEL-to-PIC insertion loss is -11.8 dB, indicating an excess coupling penalty of -5.9 dB, compared to Fibre-to-PIC coupling. Finite difference time domain simulations indicate that the penalty arises from the relatively poor match between the VCSEL mode and the grating-coupler.

Optical neuron stimulation arrays are important for both in-vitro biology and retinal prosthetic biomedical applications. Hence, in this work, we present an 8100 pixel high radiance photonic stimulator. The chip module vertically combines custom made gallium nitride μ LEDs with a CMOS application specific integrated circuit. This is designed with active pixels to ensure random access and to allow continuous illumination of all required pixels. The μLEDs have been assembled on the chip using a solder ball flip-chip bonding technique which has allowed for reliable and repeatable manufacture. We have evaluated the performance of the matrix by measuring the different factors including the static, dynamic power consumption, the illumination, and the current consumption by each LED. We show that the power consumption is within a range suitable for portable use. Finally, the thermal behavior of the matrix is monitored and the matrix proved to be thermally stable.

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Integrated photonics is a promising route toward high-performance next-generation ICT and sensing devices. Although fiber-packaging is perhaps the most widely discussed obstacle to low-cost photonic devices, electronic-photonic integration and thermal-stabilization are also significant design considerations that need to be properly managed. Using a state-of-the-art Si-photonic optical-network-unit as a worked example, we illustrate some key challenges and solutions in the field of photonicpackaging. Specifically, we describe a novel solder-reflow bonding process for the face-to-face three-dimensional (3-D) integration of photonic and electronic integrated circuits, discuss current and future multichannel fiber-alignment techniques, and investigate the coefficient-of-performance of the thermo-electric cooler that stabilizes the temperature of the photonic components. The challenge of photonic-packaging is to simultaneously satisfy these electrical, optical, and thermal design requirements on small-footprint devices, while establishing a route to scalable commercial implementation.