Collaboration to Scale Up Silicon Photonics Testing for Lidar

CompoundTek Pte Ltd., a foundry service provider in silicon photonics solutions, will collaborate with lidar solutions provider Voyant Photonics to establish a high-volume silicon photonics (SiPh) wafer test for lidar. The test is to be specifically designed for automotive applications, as well as other fast-growing applications such as robotics and drones.

Wafer-level testing enables faster yield feedback for lidar developers to capture potential excursion while in the fab, as opposed to later stages of development. It also minimizes cost of yield dropout in the later stages of the packaging process.

“The explosive growth of incorporating lidar in many applications requires us to test our SiPh chips in both timely and cost-efficient ways. A test platform that offers repeatable and reliable SiPh wafer level electro-optical testing is critical to achieve this goal,” said Lawrence Tzuang, Voyant’s principal engineer.

Voyant announced in December that it raised $15.4 million in Series A funding and made its developer kits available to select customers on its waiting list.

The integration of optical and electrical components together on a single chip creates challenges in wafer-level testing of SiPh devices. Large volumes of optical, electrical, and electro-optical device-performance data are required through various stages of the product development life cycles. Stringent wafer testing for defects in applications using lidar is necessary as the consequences of test escapes can be hazardous and detrimental to life and property.

CompoundTek announced the collaboration with Voyant two days after reporting it demonstrated a hybrid O+C+L band wavelength tunable laser module. The demonstrated laser engines operated simultaneously in the three wavebands at a wavelength tuning range of 175 nm across the bands, which span 1260 to 1625 nm in combination, and with an output power and side-mode suppression ratio as high as 40 mW and 50 dB, respectively.

The advantage of the laser, CompoundTek said, is in its ability to reduce the complexity of optical systems. A single wavelength-tunable laser can replace an array of single-wavelength lasers. This can also help to reduce inventory cost. Distributed feedback (DFB) laser arrays and microelectromechanical systems (MEMS) vertical cavity surface-emitting lasers (VCSEL) have demonstrated wavelength-tuning functionality. DFB arrays are limited by their coupler loss, however, and MEMS VCSELs can suffer mechanical instability.

Certain external cavity lasers have also indicated wide operating wavelength range. However, the application-space of the laser class is limited by bulk and higher vulnerability to environmental vibrations.

The demonstration occurred during a test that CompoundTek ran with a company currently operating in stealth mode.