Tuning the plasmon resonance of a nano-mouth array

We have developed a method to fabricate a silver nano-mouth array via a cost-effective inverted hemispherical colloidal lithography method. It shows that the nano-mouth supports a strong localized surface plasmonresonance,which results in anextraordinary opticaltransmission peak. When the nano-moutharray is transferred on to a polydimethylsiloxane (PDMS) substrate, we show that the localized surface plasmon resonance can be tuned via the swelling and recovery of the PDMS in ethyl acetate solvent. The resonant peak can be tuned with a relative bandwidth of over 10%. We also demonstrate the refractive index sensitivity of the nano-mouth array at a wavelength of 1300 nm. This structure might be useful for optical microfluidic devices and sensors