Study on picosecond collinear eight Stokes Raman laser generation

Stimulated Raman Scattering in Alkali-Earth Tungstate and Molybdate Crystals at Both Stretching and Bending Raman Modes under Synchronous Picosecond Pumping with Multiple Pulse Shortening Down to 1 ps

“…The individual pump pulses can be shorter than τ c and even ultra-short realizing transient SRS in a cavity. Such systems are synchronously pumped Raman lasers [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82]. If we use a train of ultra-short pulses with the pulse train duration of t p at the individual pulse duration of τ p , the extracavity synchronously pumped SRS oscillation threshold will be defined by expression (12) where τ p should be replaced with t p and p = 1 for both ring and linear cavities (at τ p < τ c we have gain only in the forward direction) but the SRS gain G (and its threshold value G th in expression (12)) is defined by τ p as before by expression (8).…”

860 fs GdVO4 Raman laser at 1228 nm pumped by 36 ps, 1063 nm laser

“…Generation in Raman laser was obtained by synchronization of the pump pulse repetition rate with the Raman laser cavity round-trip time [1][2][3][4][5][6][7][8][9][10][11]. The case of perfect synchronization corresponded to the lowest Stokes generation threshold and the highest Stokes radiation output energy.…”

“…Stimulated Raman scattering (SRS) as an important trend in nonlinear optics is directed to solve challenges in laser physics associated with not only frequency conversion into new spectral ranges, but also improvement of laser radiation characteristics especially temporal self-compression and output power increase. Today, we can observe progress in the physics of crystalline Raman lasers in efficient nonlinear frequency conversion in the transient regime for generation of ultra-short pulses of Stokes radiation with picosecond duration and shorter [1][2][3][4][5][6][7][8][9][10][11]. For a long time, realization of femtosecond Raman generation in crystals was an unsolved scientific problem as the Raman gain strongly decreases with decreasing pump laser pulse duration to values shorter than the dephasing time of optical phonons, which is of the order of a picosecond for most of the crystals.…”

“…Using this effect, the strongest shortening of the first Stokes pulse down to 1 ps (it is also close to the inverse width of the Raman line) has been achieved in a LiIO 3 crystal [18]. In recent years, this method was tested on many Raman-active crystals such as CVD-diamond [1,[4][5][6]8], KGd(WO 4 ) 2 [2], BaWO 4 [9,10], and SrMoO 4 [11]. It is necessary to note that, when cascade Stokes generation occurred in the synchronously-pumped extracavity Raman laser, the strongest Stokes pulse shortening was observed for high-order Stokes components [1,[9][10][11] because of activation of the additional 'intracavity' mechanism of Raman pulse shortening.…”

Synchronously-pumped, all-solid-state, picosecond Raman laser at 1169 and 1222 nm on single and combined Raman modes in a Ca3(VO4)2 crystal with 30-times pulse shortening down to 1.2 ps

“…Development of crystalline Raman lasers generating ultrashort pulses simultaneously at several wavelengths in the infrared region is interesting for many applications in science and technology, medicine and biology, for example, two-color multiphoton imaging of living tissue [1]. Method of synchronous pumping of crystalline Raman lasers allowed to obtain efficient ultra-fast SRS generation in the cases of picosecond and even femtosecond pumping in spite of a low Raman gain at the transient regime of SRS [1][2][3][4][5][6][7]. It also opens new possibilities to expand a number of usable Raman-active crystals and a number of its Raman modes having relatively low Raman gain due to strong broadening of Raman lines in spontaneous Raman spectrum.…”