Recent advances in ultrafast fiber laser: science & applications

Due to benefits including strong heat dissipation, high energy conversion efficiency, low production costs, and outstanding beam quality, the fiber oscillator has advanced quickly since its conception. As an ideal ultrashort pulse source, femtosecond fiber lasers can now generate few-cycle pulses with output peak power exceeding the megawatt level and repetition rates up to gigahertz levels, thus serving as a key driver for scientific and technological advances in ultrafast science, precision metrology, advanced manufacturing, and other fields. Over the past five years, numerous breakthrough research progresses have emerged in this field, ranging from saturable absorbers with high damage thresholds capable of supporting femtosecond pulse generation, to novel high-repetition-rate passive mode-locking schemes with repetition rates exceeding 20 GHz, and to the design of high-power fiber laser systems delivering average output power of over 100 watts. All these achievements demonstrate the vibrant technological trends in this area. Furthermore, with the development of artificial intelligence, its integration with fiber lasers has become increasingly evident. Applications such as intelligent mode-locking, soliton shape customization, and inverse design of key devices have attracted significant attention. This review systematically summarizes recent progress in femtosecond fiber oscillators, covering core mechanisms, advanced applications, and cutting-edge scientific research. It elaborates on the background, core value, and technical bottlenecks, focuses on core pulse generation technologies, explores applications in AI regulation, microscopy, optical comb construction, and trace gas detection, summarizes basic research, and outlines future trends. Following a "technical foundation-cutting-edge applications-scientific research-future trends" framework, this review comprehensively presents the development panorama, providing a systematic reference for related fields.