| AVS 63rd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Monday Sessions |
| Session NS-MoM |
| Session: | Nanopatterning and Nanofabrication + 3D |
| Presenter: | Steven Kooi, Massachusetts Institute of Technology |
| Correspondent: | Click to Email |
A combination of two-photon (2PL), holographic and direct write lithography, in positive and negative tone photoresists as well as photopatternable hydrogel materials, is used to produce nano and microscale structures for photonic, phononic and mechanical applications. The lithographic processes are described as well as the conversion of the 3D structures into higher index of refraction materials (Si, Ge and metals) for photonic applications and engineered modulus materials for phononic and mechanical applications by atomic layer deposition, chemical vapor deposition, chemical etching and ion etching techniques. Standard piezo stage scanning two-photon lithography is used to produce 3D structures as well as an upgraded design that incorporates galvo-scanning mirrors that greatly increase the writing speed and area.
The conversion of polymeric structures to higher index materials allows us to access more interesting and measurable optical properties in the visible wavelength range. Optical measurements include reflectivity to characterize optical bandgaps and to evaluate structural uniformity and quality. In addition, near field scanning optical microscopy (NSOM) techniques are used to follow light propagation through engineered photonic structures. These results are compared to theoretical predictions of optical properties and are used to evaluate not only the defect density in the printed structures, but also the quality of the multi-step conversion process. The 3D structures are also characterized by serial focused ion beam (FIB) milling and imaging.
Phononic and mechanical 3D structures are also produced by the same lithographic techniques. These materials are tested by light scattering techniques to evaluate phononic properties as well as static and dynamic mechanical measurements to investigate size and structure dependent mechanical properties. 2PL is also used to produce periodic structures that are used in laser-induced shock wave imaging experiments. These experiments are designed to study the influence of the periodic structures on the propagation and/or mitigation of shock waves.