Organic thin-film lasers have the promising feature of being able to arbitrarily oscillate a wide range of wavelengths from the visible region to the infrared region, which is difficult to achieve with inorganic lasers. It is expected to be applied.

　In order to oscillate an organic molecule by laser, it is necessary to supply energy to the organic molecule from the outside to form a high-density excited state organic molecule.The method of forming an excited state using light such as ultraviolet rays as external energy (this method) is called photoexcitation, and the method of forming an excited state using current as external energy is called current excitation.

　The photoexcited organic thin film laser of this study is composed of an organic laser active layer and an optical resonator containing a structure called "DFB structure".In the conventional device structure, the absorption of laser light by organic molecules, thermal deterioration and light loss in the organic laser active layer are large, and the continuous oscillation time of the organic thin film laser is greatly limited.

　In this study, we used organic laser molecules in the active laser layer to reduce the absorption of laser light, and removed the factors that hinder the oscillation of the organic thin film laser.In addition, heat dissipation measures are taken on the lower substrate of the organic thin film laser element to suppress thermal deterioration.Furthermore, the optical loss was suppressed by using the optimized DFB structure as the optical resonator structure.By tackling these issues, it is said that it succeeded in the world's longest continuous laser oscillation reaching 30 milliseconds.

Paper information:[Science Advances] Toward continuous-wave operation of organic semiconductor lasers