Influence of Processes of Photobleaching on Spectral Characteristics of Organic Nonlinear Optical Co-crystal 26DAP4N Topics: Molecular Photophysics and Spectroscopy; Nonlinear Optics and Photonics; Optical Materials and Devices In Proceedings of the 7th International Conference on Photonics, Optics and Laser Technology PHOTOPTICS - Volume 1, 220-224, 2019 , Prague, Czech Republic