Enhanced stimulated raman scattering of solvent due to anharmonic energy transfer from resonance raman solute molecules

Enhancement of stimulated Raman scattering of a weak vibration mode in tetrahydrofuran through the energy-transfer resonance of lycopene

A method of energy-transfer resonance of lycopene used to enhance stimulated Raman scattering (SRS) of a weak vibration C-O mode in tetrahydrofuran (THF) was developed in this study. Only C-H SRS was observed in pure THF at high energies. When lycopene was added, the C-O SRS located at 915 cm-1 of the weak vibration mode in THF was observed. The maximum SRS enhancement of the C-O mode was achieved when the concentration was 3.72 × 10-6 mol/L because of the resonance enhancement of the solute, which transferred the excess vibrational energy to the solvent. Moreover, the pulse width compression phenomenon of the C-H vibration in the presence of C-O SRS was obtained.

Temperature dependence of stimulated Raman scattering from a VYO4 crystal

The microstructural, electrical, and optical properties of crystals are critical to laser device performance, and the temperature-dependence effect of crystals has gained a great deal of attention in research. The linewidth, stimulated Raman scattering (SRS) shift, and intensity of the characteristic peak at 890 cm^-1 of YVO₄ crystal have been investigated between 148 and 448 K. As the crystal temperature increases, the bond length increases and the crystal force constant decreases, and the phonon softening process arises in the crystal at high temperature. The temperature effect on Raman shift and full width at half maximum is explained in detail in terms of the phonon anharmonic effect. The temperature dependence of SRS can be well demonstrated by an empirical equation. This work can provide new insights into the further understanding of lattice anharmonicity and contribute to the discovery of new optoelectronic materials.

Efficient frequency conversion and the crossing-pump effect of stimulated Raman scattering in an aqueous sodium sulfate solution

The cascaded stimulated Raman scattering (SRS) of an aqueous sodium sulfate solution was investigated as well as the generation of the crossing-pump effect. With the introduction of dual sample cells, the first-order Stokes of the O-H stretching vibrational mode was able to act as the pump light to excite the Stokes of the S-O stretching vibrational mode, and a new Raman peak was obtained at 4423 cm^-1. The dual sample cell device not only lowered the SRS threshold, but also enhanced the four-wave mixing (FWM) process. Compared to the input laser of 7 ns/pulse, the first-order Stokes of O-H was compressed to a pulse width of 413 ps after passing through the dual sample cells. The SRS of aqueous sodium sulfate solution covered an ultrabroad wavelength ranging from 441 nm to 720 nm (a Raman shift ranging from -3859 cm^-1 to 4923 cm^-1). The cone-shaped launch ring of the FWM process was also recorded. This work provides a reference for the establishment of laser frequency conversion devices using an aqueous sodium sulfate solution as the Raman medium.

Advances in stimulated Raman scattering imaging for tissues and animals

Stimulated Raman scattering (SRS) microscopy has emerged in the last decade as a powerful optical imaging technology with high chemical selectivity, speed, and subcellular resolution. Since the invention of SRS microscopy, it has been extensively employed in life science to study composition, structure, metabolism, development, and disease in biological systems. Applications of SRS in research and the clinic have generated new insights in many fields including neurobiology, tumor biology, developmental biology, metabolomics, pharmacokinetics, and more. Herein we review the advances and applications of SRS microscopy imaging in tissues and animals, as well as envision future applications and development of SRS imaging in life science and medicine.