Detection of a new SRS‐promoting phonon mode and cross‐cascaded χ⁽³⁾‐nonlinear lasing in single crystals of calcite (trigonal CaCO₃)

Abstract

For calcite (CaCO3), one of the pioneer crystals in nonlinear optics, new results of stimulated Raman scattering (SRS) spectroscopy are presented. Among them are the discovery of a new SRS‐promoting vibration mode with ωSRS2 ≈︁ 282 cm‐1 and its participation, together with the main SRS mode ωSRS1 ≈︁ 1086.5 cm‐1, in cross‐cascaded (χ(3) ↔ χ(3)) nonlinear‐lasing generation, as well as the observation of efficient self‐upconversion via cascaded parametric four‐wave processes of one‐micron Stokes and anti‐Stokes χ(3)‐lasing into the UV‐region of third harmonic generation. The investigations show that calcite is able to generate a χ(3)‐lasing comb of more than two octaves bandwidth. The article also gives a brief review on the discovery and study of the SRS‐effect in natural crystals (minerals), which have expanded our ability to study the photon‐phonon nonlinear‐laser interactions in crystalline materials. A short summary of information about χ(3)‐lasing properties of the triangular planar structure units in SRS‐active crystals is included.

Cerussite, PbCO3 – a new Stimulated Raman Scattering (SRS)‐active crystal with high‐order Stokes and anti‐Stokes lasing

“…For the excitation of single pass (cavity‐free) Raman‐induced Stokes and anti‐Stokes χ (3) ‐lasing of cerussite single crystals in the visible, near‐ and mid‐IR range, we used a SRS‐setup based on a home‐made Xe‐flashlamp pumped picosecond Nd 3+ :Y 3 Al 5 O 12 laser. Details of the setup and the methods of measurements are described in several recent publications (see, e.g., ). The used pump laser can emit at two fundamental wavelengths, λ f1 = 1.06415μm with pulse duration τ f1 ≈ 80 ps, or λ f2 = 0.53207 μm with τ f2 ≈ 60 ps.…”

Phosgenite, Pb2CO3Cl2 – a novel SRS‐active crystal

“…A common structural feature of the carbonates specified above is a coplanar, sheet-like arrangement of the isolated triangular [CO 3 ] groups, which alternate with sheets of M II cations in the crystal structures. The vibration modes of the [CO 3 ] groups, particularly the totally symmetric breathing mode A 1g , but also one additional (E g ) mode in calcite [2], respectively two further modes (B 1g and B 2g ) in aragonite [9], are the SRSpromoting vibration modes in these crystals. Here, the question arises, whether a carbonate crystal structure with a very different arrangement of [CO 3 2 Crystallography Crystals of Pb 2 CO 3 Cl 2 , known also as mineral phosgenite, can be found occasionally as fine specimen in nature.…”

“…The development of stimulated Raman scattering (SRS) spectroscopy of χ (2) -and χ (3) -active crystals in the last decade offered new insight into the various manifestations of nonlinear laser photon-phonon interactions and their relation to structural features. Particularly, the so far accumulated experimental data indicate, that high SRS efficiency frequently occurs in crystals with isolated structural units, such as [SO 4 ], [VO 4 ], [MoO 4 ], [NO 3 ] or [CO 3 ], which usually show SRS-activity of the totally symmetric vibration mode.…”

“…b) Measurement accuracy ± 0.0003 μm. was observed at room temperature using an experimental set-up as described in detail in several earlier studies of SRS-active carbonates, see [1,2] for calcite, CaCO 3 , [9] for aragonite, CaCO 3 , and [10] for cerussite, PbCO 3 , with slight modifications of the registration part of the set-up, see Fig. 3.…”

“…In recent investigations of stimulated Raman scattering and Raman induced four-wave mixing (RFWM) processes in crystals of the carbonate family, namely calcite (trigonal CaCO 3 ) [1,2] (but see also earlier work [3][4][5][6][7][8]), aragonite (orthorhombic CaCO 3 ) [9] and cerussite (PbCO 3 ) [10], these crystals turned out to offer several attractive manifestations of nonlinear laser interactions, such as broadband frequency comb generation, cascaded and cross-cascaded χ (3) ↔ χ (3) interactions or self-upconversion via parametric four-wave processes. In all these investigations natural crystals had been used due to the substantial experimental difficulties to grow large high quality single crystals of these compounds.…”