Abstract. The passive and hybrid Q-switching and mode-locking of solid-state lasers, dye lasers, semiconductor lasers and gas lasers is reviewed. The dynamics of saturable absorbers and reverse saturable absorbers is illustrated. The nanosecond pulse generation by passive and hybrid Q-switching of low-gain active media is described. The picosecond and femtosecond pulse generation by passive and hybrid mode-locking in low-gain and highgain active media is analysed. The performance data of passively and hybridly mode-locked cw femtosecond dye lasers are collected. The pulse shortening of ultra-fast pulses with saturable absorbers in intra-cavity and extra-cavity configurations is discussed.
PACS: 42.55The photonic switching of lasers provides an important technique to generate short light pulses in the nanosecond to femtosecond time regime. The photons generated in the laser modify the transmission of the switching elements and cause the formation of short pulses. Saturable absorbers serve as intensity or energy dependent coupling elements in most cases. But occasionally intensity and energy-dependent refractive index changes have been applied. Nanosecond light pulses are generated in passively Q-switched lasers. The passive mode-locking of laser leads to the generation of nanosecond, picosecond or femtosecond pulse trains. The actual pulse durations depend on the spectroscopic data of the active media and of the passive elements.The nonlinear response of absorbers to light radiation is introduced in the next section [1][2][3][4][5][6][7][8][9]. The passive, and the hybrid Q-switching are discussed in . The passive, and the hybrid modelocking are described in Sect. 3. A distinction is made between the mode-locking of low-gain and high-gain active media [35 45]. The simultaneous Qswitching and mode-locking is discussed shortly in Sect. 4. A final section is devoted to the intra-cavity and extra-cavity pulse shortening with saturable absorbers [46][47][48][49][50].
