Controlling nonlinear optical effects in a multimode fiber amplifier via wavefront shaping

• Applicant: Dr.-Ing. Stefan Rothe
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Measurement Systems
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541375063

Light transmission through fiber amplifiers with high average power and good beam quality is crucial for applications in telecommunications and laser material processing. While these two criteria can be easily satisfied individually, it is difficult to meet them simultaneously. Power limitations in fiber amplifiers due to nonlinear and thermal origins are usually mitigated by larger core diameters. However, this inevitably initiates the propagation of additional modes, resulting in a speckled output beam with reduction in beam quality. In this project, wavefront shaping is employed to a highly multimode fiber amplifier through which both performance indicators, namely good beam quality and high average power, are met at the same time. That implies the first-time investigation of wavefront shaping under highly nonlinear gain saturation. For this configuration, the limit of the wavefront shaping approach shall be determined, that is how much the power threshold of continuous waves in a multimode fiber amplifier can be raised suppressing the onset of nonlinear effects while maintaining good beam quality.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professorin Dr. Hui Cao