When a high-intensity laser beam passes through a transparent and homogeneous optical medium, the induced light scattering may manifest the properties of stimulated radiation characterized by threshold requirement, high directionality, and high brightness. This is the stimulated scattering of intense coherent light. Discoveries and studies of various types of stimulated scattering effects have provided a much deeper and more comprehensive understanding of interactions between the intense coherent light and matter. On the other hand, devices based on stimulated Raman scattering, stimulated Brillouin scattering, and stimulated spin-flip Raman scattering can be employed as highly efficient tunable frequency shifters of coherent light. Stimulated Kerr scattering can be used to generate a super-broadband coherent light and to investigate the molecular anisotropy of liquids. In addition, the recently developed stimulated Rayleigh–Bragg scattering and stimulated Mie scattering can significantly reduce the threshold requirement, and provide a highly efficient no-frequency-shift optical phase conjugation wave.
We theoretically investigate a scheme in which stimulated Raman scattering (SRS) can be suppressed by coherently controlling the coupling between molecular states. In conventional SRS, two laser beams at different frequencies interact resonantly with molecular vibration to induce a gain and a loss for the two beams, respectively. In our scheme, a third beam is introduced to couple the vibrational state to another coupling state. As a result, SRS is suppressed in a way analogous to electromagnetically induced transparency. We calculated the SRS signal analytically by the density matrix approach, and investigated the feasibility of this scheme for real molecular imaging. In SRS microscopy, a donut-shaped coupling laser can be used to suppress the SRS signal from the rim part of the focal spot, leading to super-resolution. Based on our numerical studies, the lateral resolution starts to be enhanced when the coupling laser intensity exceeds 0.1TW/cm2 at picosecond pulse duration.