Transfer and characterization of silicon nanomembrane-based photonic devices on flexible polyimide substrate

In this paper, we report the transfer and characterization of in-plane silicon nanomembrane based photonic devices on a Kapton polyimide flexible substrate. Compared with electronic devices and surface normal optical devices, in-plane photonic devices have stringent requirements on transfer precision because any shift in the position or breakage can affect the performance of devices. Therefore, a supporting layer consisting of a photoresist is exploited to protect the device during the transfer process. A modified stamp-assisted transfer technique is employed in order to transfer nanomembrane devices onto the flexible film and the transfer of large aspect ratio (up to 4000) waveguides and 1x6 multimode interference (MMI) couplers on a flexible Kapton substrate is demonstrated. A two-step cleaving method is developed in order to prepare the facets of the transferred waveguides and in-plane light coupling into a 60μm wide, 8mm long flexible waveguide from a lensed fiber is demonstrated. This demonstration opens limitless possibilities for a whole new area of high performance flexible photonic components using silicon nanomembrane technology.