Epsilon-near-zero surface waves enhance infrared vibrational spectroscopy

Thin film epsilon-near-zero (ENZ) supports guided modes analogous to surface plasmon modes in the infrared, where surface plasmons are difficult to excite. Leveraging these modes can enhance the signal of surface-enhanced infrared absorption (SIERA) sensors by a factor of three, enabling the detection of minute amounts of materials. However, material losses can significantly impact sensor performance. To address this issue, we establish a condition that limits the impact of losses while still preserving the advantage of ENZ-surface waves. Our findings may pave the way for the identification and exploration of particularly suitable materials for highly efficient photonic SIERA sensors.