Self-sweeping Yb-doped fiber laser generating ultra long single-frequency pulses

In this work, a self-sweeping Yb-doped fiber laser generating quasi-CW radiation is demonstrated. The laser is based on a ring configuration allowing to form running and standing waves in separate sections of the cavity. The laser generates a sequence of single-frequency (linewidth of ~0.7 MHz) ultra long (~1 ms) rectangular pulses. The laser frequency changes from pulse to pulse by one inter-mode spacing (~10 MHz). The laser signal intensity is quasi-CW signal accompanied by regular bursts generating during frequency change, and the intensity never drops to zero. The features can be useful for long term averaging when measuring weak signals.