Researchers at the Cockrell School of Engineering have created the first silicon nanomembrane based flexible photonic crystal cavity. This new form of silicon photonic devices is believed to have numerous applications in wearable devices and biomedical instruments.

Developing flexible single crystal silicon electronics and photonics is a modern instance of the archetypal human-versus-nature conflict. The enthusiasm of this effort is stimulated by a natural quandary: the well-established integrated electronics and photonics are manufactured on silicon based substrates, which are rigid; on the contrary, all organisms are soft and curvilinear.

This seemingly intrinsic incompatibility is resolved by the discovery that nanomembranes with thickness less than a few hundred nanometers can have flexural rigidities more than fifteen orders of magnitude smaller than those of bulk wafers (>200mm) of the same materials. A hybrid platform which enjoys both the high performance of inorganic materials and the flexibility of organic materials is believed to have a vast range of unprecedented applications which could not be implemented by either inorganic or organic platforms alone.

However, it is very challenging to transfer photonic devices onto flexible substrates. Ray T. Chen, professor in the school’s Department of Electrical and Computer Engineering, and his team, developed a new method and demonstrated a flexible photonic crystal cavity which can be bent to a curvature of 5 mm radius without sacrificing the performance. The work was published in the journal ACS Nano.

Supported by the MURI Center for Silicon Nanomembranes, sponsored by the AFOSR, Grant No. FA9550-08-1-0394.