Janonis Vytautas, Cernescu Adrian, Prystawko Pawel, Januškevičius Regimantas, Indrišiūnas Simonas, Kašalynas Irmantas
Terahertz Photonics Laboratory, Center for Physical Sciences and Technology (FTMC), 10257 Vilnius, Lithuania.
Attocube Systems AG, 85540 Haar, Germany.
Materials (Basel). 2025 Jun 17;18(12):2849. doi: 10.3390/ma18122849.
Near-field imaging of the hybrid surface plasmon-phonon polaritons on the n-GaN semiconductor was performed using a scattering scanning near-field optical microscope at the selected frequencies of 920 cm and 570 cm. The experimental measurements and numerical modeling data were in good agreement, revealing the large propagation distances on the n-GaN semiconductor and other insights which could be obtained by analyzing the dispersion characteristics of hybrid polaritons. In particular, the decay lengths of polaritons at the excitation frequency of 920 cm were measured to be up to 25 and 30 µm in experiment and theory, respectively. In the case of excitation at the frequency of 570 cm, the surface plasmon-phonon polaritons' decay distances were 25 µm and 105 µm, respectively, noting the limitations of the near-field optical microscope setups used. Dispersion characteristics of the resonant frequency and the damping rate of hybrid polaritons were numerically modeled and compared with the analytical calculations, validating the need for further experiment improvements. The launch conditions for the near-field observation of extraordinary coherence of the surface plasmon-phonon polaritons were also discussed.
利用散射扫描近场光学显微镜，在920厘米和570厘米的选定频率下，对n型氮化镓半导体上的混合表面等离子体激元 - 声子极化激元进行了近场成像。实验测量结果与数值模拟数据吻合良好，揭示了n型氮化镓半导体上混合极化激元的大传播距离以及通过分析混合极化激元的色散特性可获得的其他见解。特别是，在920厘米激发频率下，极化激元的衰减长度在实验和理论中分别测量为高达25微米和30微米。在570厘米频率激发的情况下，表面等离子体激元 - 声子极化激元的衰减距离分别为25微米和105微米，同时指出了所使用的近场光学显微镜设置的局限性。对混合极化激元的共振频率和阻尼率的色散特性进行了数值模拟，并与解析计算进行了比较，验证了进一步改进实验的必要性。还讨论了表面等离子体激元 - 声子极化激元异常相干近场观测的发射条件。
