Research

Our current research thrust is the fabrication and characterization of optical microstructures. We use azopolymer or photoresist films and laser interferometric lithography. Films are spin coated in our thin-film lab, and  characterized in our atomic force microscope (AFM) facilities. We are adding new capabilities for surface structure replication using nanoimprint lithography.  Read more about our projects and capabilities below.

Projects

  • Dot-matrix holography– A typical image can be written as a matrix of surface-relief microholograms. We fabricate a variety of dot-matrix holograms and are exploring multiplexing techniques for the control of color and the storage of multiple independent images to simulate motion.

 

 

  • Surface grating amplification and reconfiguration- Photomechanical azobenzene-polymer films respond to optical polarization, and can be used as optically reconfigurable surfaces. We exploit this to explore how sinusoidal surface gratings can be amplified, erased, and reconfigured via film-scanning and repeated exposure.

 

  • Supramolecular azobenzene-polymer materials– We collaborate with the TCNJ chemistry department on the development of supramolecular azobenzene-polymer films. Supramolecular materials rely on hydrogen bonding, resulting in a versatile and easily materials platform capable of surface relief gratings > 800 nm.

 

Capabilities

  • Laser interference lithography– We use 488 nm diode-pumped solid state (DPSS) lasers for laser interference lithography. For dot-matrix generation, the laser pattern remains fixed, while the film is scanned. We use Python to automate all aspects of exposure and film translation.

 

  • Structure replication– Our optical microstructures can be replicated using nanoimprint lithography.  We utilize PDMS-molding to fabricate high fidelity replicates of structures.

 

 

  • AFM– Optical microstructures are characterized primarily by atomic force microscopy (AFM). The TCNJ physics department houses a research-grade Bruker Dimension Edge AFM, which can measure film surface topography variations with sub-nanometer resolution.

 

  • Thin-film fabrication– We have a dedicated laboratory for thin-film fabrication. Solutions for photoresist and azobenzene-polymer films are prepared and deposited on a variety of substrates using spin-coating.  The lab contains a sputter coater for the deposition of metallic overcoats and for fabrication of reflective substrates.