fabrication of silver-silicon gratings for surface plasmon excitation using nanosecond laser interference lithography

We introduce a new two-step method to fabricate silver-silicon gratings that can excite surface plasmons efficiently. the grating structure was firstly created on a flat silicon substrate by single-pulse nanosecond laser interference lithography. next, a silver layer of 50 nm was evaporated on the silicon substrate. with proper laser energy, a silver-silicon grating with a period of 1120 nm and depth of 18 nm was successfully fabricated. this grating can produce high-quality surface plasmon resonance (spr) peaks at various incident angles. moreover, a spr sensor was experimentally demonstrated based on the silver-silicon grating, which had high sensitivity of 961.5 nm/riu and figure of merit of 60. our method is an efficient way to fabricate periodically nanostructured metals at high speed and low cost.