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Photonic integrated circuits have seen a dramatic increase in complexity over the past decades. This development has been spurred by recent applications in datacenter communications and enabled by the availability of standardized mature technology platforms. Mechanical movement of wave-guiding structures at the micro-and nanoscale provides unique opportunities to further enhance functionality and to reduce power consumption in photonic integrated circuits. We here demonstrate integration of MEMS-enabled components in a simplified silicon photonics process based on IMEC's Standard iSiPP50G Silicon Photonics Platform and a custom release process.

We present a gas sensitive thin-film transistor (TFT) based on an amorphous Indium–Gallium–Zinc–Oxide (a-IGZO) semiconductor as the sensing layer, which is fabricated on a free-standing flexible polyimide foil. The photo-induced sensor response to NO2 gas at room temperature and the cross-sensitivity to humidity are investigated. We combine the advantages of a transistor based sensor with flexible electronics technology to demonstrate the first flexible a-IGZO based gas sensitive TFT. Since flexible plastic substrates prohibit the use of high operating temperatures, the charge generation is promoted with the help of UV-light absorption, which ultimately triggers the reversible chemical reaction with the trace gas. Furthermore, the device fabrication process flow can be directly implemented in standard TFT technology, allowing for the parallel integration of the sensor and analog or logical circuits.

Programmable photonic integrated circuits are emerging as an attractive platform for applications such as quantum information processing and artificial neural networks. However, current programmable circuits are limited in scalability by the lack of low-power and low-loss phase shifters in commercial foundries. Here, we demonstrate a compact phase shifter with low-power photonic MEMS (micro-electro-mechanical systems) actuation on a silicon photonics foundry platform (IMEC's iSiPP50G). The device attains (2.9π ± π) phase shift at 1550 nm, with an insertion loss of (0.33 + 0.15 − 0.10 ) dB, a V π of (10.7 + 2.2 − 1.4 ) V, and an L π of (17.2 + 8.8 − 4.3 ) µm. We also measured an actuation bandwidth f -3dB of 1.03 MHz in air. We believe that our demonstration of a low-loss and low-power photonic MEMS phase shifter implemented in silicon photonics foundry compatible technology lifts a main roadblock towards the scale-up of programmable photonic integrated circuits.

Directional couplers are extensively used in photonic integrated circuits as basic components for efficient on-chip photonic signal routing. Conventionally, directional couplers are fully encapsulated in the technology’s waveguide cladding material. In this Letter, we demonstrate a compact broadband directional coupler, fully suspended in air and exhibiting efficient power coupling in the cross state. The coupler is designed and built based on IMEC’s iSiPP50G standard platform, and hydrofluoric (HF) vapor-etching-based post-processing allows to release the freestanding component. A low insertion loss of 0.5 dB at λ = 1560 n m and a 1 dB bandwidth of 35 nm at λ = 1550 n m have been confirmed experimentally. With a small footprint of 20 µ m × 30 µ m and high mechanical stability, this directional coupler can serve as a basic building block for large-scale silicon photonic microelectromechanical systems (MEMS) circuits.