Stavrou Michalis, Zyla Gordon, Ladika Dimitra, Dumur Frederic, Farsari Maria, Gray David
Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Heraklion 70013, Greece.
Aix Marseille Univ, CNRS, ICR, UMR 7273, Marseille F-13397, France.
ACS Appl Opt Mater. 2024 Aug 5;2(8):1653-1666. doi: 10.1021/acsaom.4c00241. eCollection 2024 Aug 23.
The present work reports on the ultrafast nonlinear optical (NLO) properties of a series of D-π-Α and D-A push-pull carbazole-based dyes and establishes a correlation between these properties and their efficiency for potential photonic and optoelectronic applications such as multiphoton lithography (MPL). The ultrafast NLO properties of the studied dyes are determined by two distinct experimental techniques, -scan and pump-probe optical Kerr effect (OKE), employing 246 fs laser pulses at 515 nm. The results indicate that chemical functionalization of the carbazole moiety with various strong electron-donating and/or electron-withdrawing groups, such as benzene, styrene, 4-bromostyrene, nitrobenzene, trimethyl isocyanurate, methyl, and indane-1,3-dione, can result in a controlled and significant enhancement of the NLO absorptive and refractive responses. In the context of potential applications, the efficiency of carbazole-based organic materials as photoinitiators (PIs) for MPL applications is demonstrated. The fabricated woodpile microstructure using chemically functionalized carbazole as a PI demonstrates improvements in both feature size and MPL efficiency compared to that using unfunctionalized carbazole as a PI. This is attributed to the efficient charge transfer resulting from chemical functionalization, which leads to a substantial increase (approximately 1 order of magnitude) in the values of the imaginary part of the second-order hyperpolarizability (Imγ) and the two-photon absorption cross section (σ). The achieved feature size of 280 nm is comparable to that obtained with other widely used PIs in MPL applications. Additionally, owing to the strong NLO properties of the studied functionalized carbazole, they could also be promising candidates for further applications in photonics and optoelectronics.
本工作报道了一系列基于D-π-Α和D-A推挽咔唑的染料的超快非线性光学（NLO）性质，并建立了这些性质与其在多光子光刻（MPL）等潜在光子和光电子应用中的效率之间的相关性。所研究染料的超快NLO性质通过两种不同的实验技术——-扫描和泵浦-探测光学克尔效应（OKE）来确定，采用515 nm的246 fs激光脉冲。结果表明，咔唑部分用各种强供电子和/或吸电子基团进行化学功能化，如苯、苯乙烯、4-溴苯乙烯、硝基苯、三甲基异氰脲酸酯、甲基和茚满-1,3-二酮，可导致NLO吸收和折射响应的可控且显著增强。在潜在应用方面，展示了基于咔唑的有机材料作为MPL应用的光引发剂（PI）的效率。与使用未功能化咔唑作为PI相比，使用化学功能化咔唑作为PI制造的木堆微结构在特征尺寸和MPL效率方面都有改进。这归因于化学功能化导致的有效电荷转移，这导致二阶超极化率虚部（Imγ）和双光子吸收截面（σ）的值大幅增加（约1个数量级）。实现的280 nm特征尺寸与MPL应用中其他广泛使用的PI所获得的尺寸相当。此外，由于所研究的功能化咔唑具有很强的NLO性质，它们也可能是光子学和光电子学进一步应用的有前途的候选材料。
