An experimental study of saturable absorbers for ruby lasers

Passive Q-switching and mode-locking for the generation of nanosecond to femtosecond pulses

“…The relaxation from level 4 to level 3 is generally very short (T<, x ->0). Saturable absorbers [1][2][3][4][5][6][7][8][9] are characterized by a A >a ex ( Fig. 2a and b).…”

“…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 .…”

Incoherent “Slow and Fast Light”

“…Sometimes, the nonlinearity of this kind arises in optical systems All the aforesaid actually refers to well-known effects of nonlinear optics (or, better to say, of nonlinear physics). In particular, the effect of the light pulse delay in a saturable absorber is known for more that 40 years [3], and the media with intensity nonlinearity are widely used starting from 60s in passive systems of Q-switching and mode-locking [4,5]. In the end of the 20th century, however, the above effects of retarded response of a saturable absorber have been rediscovered [6,7] and, without mentioning the known mechanism of their origination, were ascribed to the light-induced changes in the group velocity of light in saturable absorbers.…”

Saturable absorbers with concentration-dependent absorption recovery time

“…42.65, 42.70, 42.20 The bleaching of absorbing media by intense light pulses is a general phenomenon. The only requirement for reduction of absorption with increasing light signal is that the ground-state absorption cross-section is larger than the excited-state absorption cross-section [1][2][3][4][5]. For laser pulse durations At L short compared to the absorption recovery time z A the bleaching behavior is determined by the input pulse energy density e [6].…”

“…For laser pulse durations long compared to the absorption recovery time the light transmission is intensity dependent. At a pulse intensity of h = hv L /(T L T A , the saturation intensity, the groundstate population is reduced to approximately half its initial value [1][2][3][4][5][6]. The application of saturable absorbers as modelocking dyes requires absorption recovery times short compared to the resonator round-trip time.…”