“…At the same time, semiconductor polymers are fascinating materials for studying nonlinear optical effects such as two-photon absorption (2PA). Organic materials for 2PA are interesting for applications in 3D micro-fabrication and micromachining [ 7 , 8 , 9 , 10 ], 3D data storage [ 11 , 12 ], optical power limiting [ 13 , 14 ], two-photon induced photopolymerization [ 15 ], two-photon pumped laser [ 16 ], and so on. The key feature for such applications is the quadratic dependence of the 2PA process on the excitation irradiance, which provides spatial confinement of excitation [ 17 ].…”