Kachiraju Satya R, Nekrashevich Ivan, Ahmad Imtiaz, Farooq Hira, Chang Long, Kim Sangsik, Kim Myoung-Hwan
Department of Physics and Astronomy, Texas Tech University, Lubbock, TX 79409, USA.
Department of Physics and Astronomy, The University of Texas Rio Grande Valley, Brownsville, TX 78520, USA.
Nanophotonics. 2022 Sep 12;11(20):4489-4498. doi: 10.1515/nanoph-2022-0339. eCollection 2022 Sep.
Resonant optical cavities are essential components in mid-infrared applications. However, typical film-type cavities require multilayer stacks with a micron-thick spacer due to mid-infrared wavelengths, and their performance is limited by narrow frequency tunability and angular sensitivity. We propose and experimentally demonstrate the subwavelength-scale (≈ /150) resonant nanocavity arrays that enhance the absorption spectrum of the device in the mid-infrared (10-12 microns) via excitation of coupled surface plasmon-phonon polaritons. The proposed metal-insulator-polar dielectric (gold-silicon-silicon carbide) structure supports a guided mode of the coupled surface polaritons in the lateral direction while vertically confining the mid-infrared wave within the 80 nm thick dielectric spacer. In particular, the subwavelength-scale (≈ /10) gratings are imposed to form Fabry-Pérot cavity arrays displaying angle-insensitive and frequency-tunable absorption of up to 80% of the optical power in the mid-infrared. Our work should benefit diverse mid-infrared applications and novel designs of polariton-based photonic devices.
共振光学腔是中红外应用中的关键组件。然而，由于中红外波长的原因，典型的薄膜型腔需要带有微米级厚间隔层的多层堆叠结构，并且其性能受到窄频率可调性和角度敏感性的限制。我们提出并通过实验证明了亚波长尺度（≈λ/150）的共振纳米腔阵列，该阵列通过耦合表面等离子体 - 声子极化激元的激发来增强器件在中红外（10 - 12微米）波段的吸收光谱。所提出的金属 - 绝缘体 - 极性电介质（金 - 硅 - 碳化硅）结构在横向支持耦合表面极化激元的导模，同时在垂直方向上将中红外波限制在80纳米厚的电介质间隔层内。特别地，施加亚波长尺度（≈λ/10）的光栅以形成法布里 - 珀罗腔阵列，该阵列在中红外波段显示出对角度不敏感且频率可调的吸收，吸收的光功率高达80%。我们的工作应会惠及多种中红外应用以及基于极化激元的光子器件的新颖设计。
