Scientists Develop Innovative Process for Plasmonic Nanogap Array Production

A research team led by Dr. Stefan Strauf, who serves as the Director of the NanoPhotonics Laboratory (NPL) at Stevens Institute of Technology, has developed a new method based on holographic lithography (HL) process for producing plasmonic nanogap arrays, which are evenly placed metallic nanostructures.

The novel method enhances the production of plasmonic nanogap arrays, while concurrently decreasing expenditure and setup. Existing nanogap array production methods are time-consuming and expensive and have low output.

Plasmonic nanogap arrays have small air gaps between them. By generating strongly controlled electrically fields using optical illumination, these small air gaps enable researchers to utilize the arrays in numerous applications, including ultra-sensitive sensing and photonic circuit miniaturization. Such sensors could be utilized in high-resolution microscopy or are useful in determining the presence of certain chemicals or proteins at single molecule level. Nanophotonic circuits, which can transfer large quantities of data, are critical in future-generation computing power.

HL, an optical method that produces periodic patterns using interference patterns of laser beams, was earlier utilized for the formation of sub wavelength features. The research team upgraded the HL process by coupling the compound lattice concept and four-beam interference to produce tunable twin motive patterns into a polymer template, yielding metallic nanostructures with air gaps as low as 7 nm, which is 70 folds lesser than the blue laser light wavelengths used to create the features.

The researchers scaled up the usage of HL method to form gaps with yields equivalent to that of painstaking serial production methods such as focused ion beam milling or electron beam lithography. Their method is not only easier and economical but does not need a clean room. At present, the unique method attains 90% consistency in the array pattern. It realizes the rapid and economical production of large-scale superior-quality arrays.