A dissipative soliton resonance (DSR) pulse is a special output pulse from a mode-locked fiber laser. The pulse duration increases linearly with the increase of the pump power. At the same time, the peak power of the pulse is clamped, which means the pulse energy increases linearly. With the development of mode-locking technologies and rare-earth element doping technologies, DSR fiber lasers have been developed rapidly. As we all know that in the past few decades, various pulse shaping mechanisms have been successively proposed to improve the pulse energy from a fiber laser. Soliton is the first to be proposed and the pulse can maintain its shape when propagating in a laser cavity. However, the output pulse has a low pulse energy and is easy to break. Subsequently, a dispersion-managed soliton is proposed and by controlling the dispersion map in the cavity, one can get a pulse with a higher energy. Further, the self-similar and gain-guided soliton has been reported, and the dissipative solitons operating in the normal dispersion region have been subsequently observed experimentally. On this basis, the dissipative soliton resonance pulse has been confirmed by theoretical prediction and experimental observation. The research on DSR pulses is of great significance because the DSP pulse possess the potential to achieve a larger pulse energy. The properties of DSR fiber lasers under various laser cavity structures and various mode-locking methods have been investigated, and the DSR pulses with different center wavelengths have been realized. In addition, the research on the evolution characteristics of a DSR pulse in a cavity has also attracted lots of attention in recent years. Some anti-DSR phenomena including period doubling (PD) and pulse shrinkage are observed and explored. These studies can help us better understand the developing characteristics of DSR pulses, and find a way to further improve the pulse energy.
We first introduce the research background of DSR pulses, then illustrate the pulse generation mechanism and the corresponding characteristics. The DSR fiber lasers under different mode-locking mechanisms are summarized. Finally, the state-of-the-art research status and potential applications are comprehensively illustrated. This paper discusses and compares the output characteristics, advantages, and disadvantages of different mode-locked DSR fiber lasers. The performance of the existing DSR fiber lasers is discussed and analyzed, and the anti-DSR phenomena and the influence of the spectral filtering on the DSR pulses are also discussed. Under ideal conditions in time domain, the DSR pulse duration is linearly proportional to the gain. In other words, the DSR pulse is broadened in the increase process of gain, and so does the corresponding pulse energy. However, some phenomena that contradict theoretical predictions have been experimentally observed. The first is PD, a classical property of a nonlinear system. The DSR pulses are theoretically immune to the appearance of PD as the DSR pulses have clamped peak powers with the increase of pump power, while PD is a nonlinear threshold effect. However, the PD phenomenon has been experimentally observed and numerically demonstrated. In addition to the periodic bifurcation of a single pulse, the periodic bifurcation under the double-pulse and multi-pulse states has also been observed. The study of the periodic bifurcation state can help us to understand the DSR pulse more comprehensively and to avoid this nonlinear effect for efficiently boosting the pulse energy further. Pulse shrinkage is another anti-DSR phenomenon. As the gain continues to increase, the DSR pulse is not broadened but narrowed. In the simulation, by constructing a filter whose center wavelength varies with the effective gain, one can obtain the shrinkage phenomenon similar to the experimental results. In addition, by adjusting the parameters, we further observe DSR pulse shrinkage in the PD state. The exploration of this phenomenon is helpful for us to understand the hindrance in the energy increase process of a DSR pulse.
DSR pulses have a broad application prospect in the fields of laser processing and laser medical treatment, and also have a great potential in obtaining high energies. Whether different mode-locking methods and intra-cavity structures are used or doped fibers at different wavelength ranges are adopted, researches on DSR pulses have always been in pursuit of higher and higher pulse energies. By exploring the DSR properties, one can comprehensively understand how to control the filtering effect in the cavity to obtain a higher pulse energy. The investigation on the anti-DSR phenomena can help us to understand the physical mechanism for the interruption of the continuous increase of pulse energy, and can further guide us to avoid this phenomenon, which in turn helps us to further improve the achievable pulse energy. In addition, finding new types of DSR pulses, such as considering DSR pulses operating in a multi-mode state, and exploring the generation and characteristics of a multi-mode DSR, are also conducive to further improve the pulse energy.
