Flexible in-plane photonic devices based on transferrable Si nanomembranes on polyimide film

The flexible electronics and photonics have attracted a lot of attentions in past decade because of their potentially wide applications. A general method to fabricate nanomembrane flexible device involves two steps. At first, a nanomembrane on top of a sacrificial layer is patterned. Then, the nanomembrane is freed by high selective etching of the sacrificial layer and then weakly bonds to the handle substrate by Vander Waals forces. Later on, the released devices are transferred to the target flexible substrates. Notable successes include paper-like display, flexible silicon integrated circuits, photonic crystal filter and sensor skins, and so on. However, the progress in flexible photonic device is still limited to surface-normal devices such as photonic crystal filter. This type of devices usually has a large area and/or same dimensions which makes the transfer much easier than in-plane photonic device. This paper reports the transfer of in-plane Silicon nanomembrane photonic devices on polyimide flexible film. Employing a slightly modified transfer process, passive optical components, such as optical waveguide and multimode multimode interferometer, are successfully transferred on to Kapton polyimide film.