In the MORPHIC project we have developed silicon photonic MEMS technology for large-scale programmable photonic integrated circuits (PIC) that can be configured in software for different applications. PICs are chips to manipulate light, and today they are used for fibre-optic communications, sensors, spectroscopy and quantum optics. Silicon photonics is a unique PIC technology that leverages the fabrication technologies for CMOS electronics, allowing very compact waveguides and complex circuits.
Developing a new PIC is costly: it takes a year for design, fabrication and test, similar as in electronics. However, in electronics, programmable chips like FPGAs can be purchased off the shelf, providing easy access to the technology.
MORPHIC wants to enable the same model for photonics, creating an optical equivalent of the FPGA. Such a programmable PIC consists of many tunable elements connected by a dense mesh of waveguides, in which the routing of light is controlled electronically. The photonic chip thus requires electronic drivers and the software algorithms to implement a useful function.
As the light passes through many tunable building blocks, these must be efficient, compact and have low power consumption. That is why MORPHIC has extended silicon photonics with micro-mechanical tuning elements (MEMS) consisting of suspended waveguides that can be moved by applying a voltage, affecting the phase delay or the coupling between waveguides. These MEMS consume very little power and, with mechanical latching, can even maintain their state without external power. To protect the exposed MEMS from the environment, we have developed a wafer-scale hermetic sealing procedure for the MEMS.
To enable large-scale circuits, MORPHIC has developed an interposer packaging technology to connect thousands of tunable elements to their driver electronics, specifically developed for the high actuation voltage needed by the MEMS devices. These are wrapped in a software framework that helps the designer to visualize, configure, simulate and test the programmable photonic circuits.
The MORPHIC project targeted three applications to demonstrate its capabilities: optical switches for fiber-optic communication, optical processing of signals for 5G communication, and beamforming for free-space light communication and LiDAR. MORPHIC implemented demonstrator circuits for each application, and also a generic programmable PIC that can be configured for these three applications, testing the viability of this photonic equivalent of the FPGA. These demonstrators are currently under assembly and test.
MORPHIC brings together the full supply chain for programmable PICs, from the silicon photonics and MEMS processing to the packaging schemes, electronics and programming tools, to establish a new way of working with generic PICs that can be customized in software. This lowers the threshold for trying new PIC concepts and can reduce the time for first prototypes from months to weeks.
