Wang Hsuan-Sen, Su Shih-Po, Huang Yi-Hsuan, Tu Li-Wei, Wadekar Paritosh V, Wang Hsiang-Chen, Lee Chao-Kuei
Department of Photonics, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan.
Department of Physics, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan.
Discov Nano. 2025 Aug 6;20(1):129. doi: 10.1186/s11671-025-04321-8.
2H and 1T/1T' molybdenum disulfide (MoS) are typical phases that can be found in crystalline and thin film materials. In this work, by controlling the atmosphere during thin film chemical vapor deposition, 2H or 1T/1T' phase MoS are grown separately. Additionally, by employing the Z-scan technique, the phase-dependent optical nonlinearity of MoS is observed and investigated. The 2H phase-dominated few-layered MoS shows clear reversed saturable absorption with a peak intensity reaching [Formula: see text] 3.78 GW/cm, indicating extra higher-order nonlinear absorption. In contrast with the 2H phase, dominant single photon absorption is observed in the 1T/1T' phase MoS. In addition, the nonlinear refractive index (n) of the two phases is characterized, exhibiting values of 1.82 × 10 cm/W (1T/1T' phase) and - 4.82 × 10 cm/W (2H phase). This is the first time that the phase-dependent optical nonlinearity of MoS has been distinguished. Meanwhile, the proposed methodology not only provides information on the differences between the phases but also serves as a guide for determining suitable phases in specific applications.
二硫化钼（MoS）的2H相和1T/1T'相是在晶体和薄膜材料中可以找到的典型相。在这项工作中，通过在薄膜化学气相沉积过程中控制气氛，分别生长出2H相或1T/1T'相的MoS。此外，通过采用Z扫描技术，对MoS的相依赖光学非线性进行了观察和研究。以2H相为主的少层MoS表现出明显的反饱和吸收，峰值强度达到3.78 GW/cm，表明存在额外的高阶非线性吸收。与2H相相比，在1T/1T'相的MoS中观察到主导的单光子吸收。此外，还对这两个相的非线性折射率（n）进行了表征，1T/1T'相的值为1.82×10 cm/W，2H相的值为-4.82×10 cm/W。这是首次区分出MoS的相依赖光学非线性。同时，所提出的方法不仅提供了关于各相之间差异的信息，还为在特定应用中确定合适的相提供了指导。
