Wavelength tunable surface plasmon resonance-enhanced optical transmission through a chirped diffraction grating

Area of Science:

• Plasmonics
• Nanophotonics
• Materials Science

Background:

• Surface plasmon-enhanced optical transmission (SEOT) offers unique light-matter interaction possibilities.
• Chirped gratings with spatially varying pitch and amplitude can control optical responses.
• Developing novel substrates for tunable plasmonic devices is crucial for advanced optical applications.

Purpose of the Study:

• To construct and test a chirped diffraction grating as a substrate for SEOT.
• To investigate the relationship between grating topology and plasmonic optical response.
• To explore the potential of this surface as an information-rich optical sensor.

Main Methods:

• Fabrication of a chirped grating via plasma oxidation and nonuniform buckling of a polymer sheet.
• Replication of the polymer surface onto a gold film.
• Characterization using optical diffraction, atomic force microscopy (AFM), and normal incidence optical transmission.
• Analysis of the effect of a dielectric (silicon oxide) coating on the optical response.

Main Results:

• The gold-coated grating exhibited narrow, enhanced transmission peaks across the visible spectrum.
• Transmission peak location and magnitude varied spatially, correlating with surface plasmon excitation conditions.
• Dielectric coating induced wavelength shifts in transmission peaks, dependent on film thickness and local grating structure.
• A direct correlation was observed between grating topology and optical transmission characteristics.

Conclusions:

• The chirped diffraction grating effectively supports surface plasmon-enhanced optical transmission.
• The grating's spatially varying structure allows for tunable optical responses and serves as an information-rich sensor.
• Control over local grating topology enables fine-tuning of the sensor's properties for specific applications.