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 1×6 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.