Tunable GaN Photonic Crystal and Microdisk on PDMS Flexible Films

Flexible micro-/nanoscale photonics has shown great promise in a wide range of applications, especially those that cannot be addressed by traditional photonics based on rigid materials and structures. Flexible photonics are typically implemented by transferring compact optical devices made in high-quality crystalline semiconductors onto plastic substrates. However, success in developing flexible optical devices based on GaN micro-/nanostructures has been extremely limited. In this work, we target to overcome this bottleneck by forming GaN photonic crystals and microdisks on flexible PDMS films using a combination of nano-/microsphere lithography and laser lift-off techniques. The GaN–PDMS configurations not only endow the devices with mechanical flexibility but also enable optical tuning of the photonic bandgaps from stretchable photonic crystals and whispering-gallery-mode laser emission from bendable microdisks over a remarkably large range. Their optical properties of the devices are extensively studied through a range of spectroscopy techniques and simulations. The present demonstrations verify the feasibility of the proposed GaN–PDMS platform for forming compact flexible devices, which could pave the way toward emerging applications of flexible photonics technology.