Low-threshold parametric Raman generation of high-order Raman components in crystals

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

“…It can be explained by a dispersion effect which is stronger in long media. And one more reason is a parametric coupling effect decreasing the oscillation threshold for higher order Stokes components in short crystals because the interaction length becomes lower than a coherence length of four-wave mixing of SRS components [30]. It is confirmed by generation of not only Stokes but also anti-Stokes ( − and 2 − ) short-shifted SRS components in SrWO4 (Figure 4).…”

“…Similarly, short-shifted second Stokes (ν 1 + 2ν 2 ) generation can be explained not only by cascade SRS but also by four-wave mixing process of parametric coupling of one photon from the (ν 1 ) long-shifted Stokes component with two photons from the first (ν 1 + ν 2 ) short-shifted Stokes component and one photon from the second (ν 1 + 2ν 2 ) Stokes component. For example, for SrMoO 4 , using known Sellmeier equation [91], we can calculate wave mismatch of four-wave mixing generation of the (ν 1 + 2ν 2 )-shifted Stokes component at 1256 nm (Table 3) by the formula [30]…”

Low-threshold collinear parametric Raman comb generation in calcite under 532 and 1064 nm picosecond laser pumping

“…Recently in [4] the theoretical model of transient collinear parametric Raman generation of many Raman components in BaWO 4 and SrWO 4 crystals during dispersive FWM mismatch was developed, tested and showed agreement between the calculations and the experimental results. Using this model in [5] the conditions of low-threshold collinear wide frequency parametric Raman comb generation in crystals were theoretically studied.…”

“…In the case of collinear Stokes-anti-Stokes parametric coupling, due to the dispersion of the refractive index of the medium, a wave mismatch can be expressed as [4] πλ πν Figure 3 shows the spectra of the axially generated Raman components under the 532 nm excitation. At a crystal length of 5.3 mm (within the optimal range) the 2nd anti-Stokes up to the 4th Stokes components were observed under a pumping energy of 450 μJ, as shown in figure 3(a), but in the case of a non-optimal crystal length of 33 mm only Stokes (from the 1st to the 4th) components even for twice as high (1000 μJ) a pump energy were generated, as shown in figure 3(b).…”

Multi-wavelength picosecond BaWO4Raman laser with long and short Raman shifts and 12-fold pulse shortening down to 3 ps at 1227 nm

“…BaWO 4 also has a high optical damage threshold and good mechanical and thermal properties. This crystal can be used not only for the quasi-steady-state (nanosecond) regime of SRS [11][12][13], but also for effective transient (picosecond) Raman conversion [14][15][16]. SRS generation in an a-cut BaWO 4 crystal can be realized not only with a long Raman shift of ν 1 = 925 cm −1 but also with a short Raman shift of ν 2 = 332 cm −1 if the pump radiation is polarized along the crystal optical axis (E c).…”