Molecular emission in a high-density resonance medium

Yu. A. Vdovin

David A. Micha, Zhigang Yi

Jordi Martorell, N. M. Lawandy

We observed the change in fluorescence lifetime from a molecular dye embedded in a colloidal suspension of polystyrene spheres when the mean separation between spheres remains less than the wavelength of emission. At high densities of colloidal particles the spontaneous emission is inhibited, while as the density of colloidal particles is lowered the spontaneous emission is enhanced. This phenomenon is interpreted in terms of coherent interference from the electric field radiated by the molecular dipole and the reradiated field from the dielectric spheres.

A. V. Pakhomov, Mikhail V. Arkhipov, Nikolay N. Rosanov +1 more

We theoretically demonstrate the possibility to produce unipolar pulses of varying temporal profile in an extended layer of a resonant medium with the nonlinear coupling to the driving electric field. The proposed approach relies on the coherent control of the low-frequency medium oscillations by a sequence of ultrashort excitation pulses as well as the collective emission of multiple resonant centers along an optically thick medium layer. In particular, we show that creating an inhomogeneous spatial profile of the density of resonant centers allows obtaining unipolar pulses of adjustable waveform, such as rectangular or triangular ones. Such optical response could be realized in Raman-active media, e.g., in molecular crystals with well-resolved vibrational terahertz resonances.

Sergei N Bagayev, V. S. Egorov, Igor B. Mekhov +4 more

Experimental and numerical investigation of single-beam and pump-probe interaction with a resonantly absorbing dense extended medium under strong and weak field-matter coupling is presented. Significant probe beam amplification and conical emission were observed. Under relatively weak pumping and high medium density, when the condition of strong coupling between field and resonant matter is fulfilled, the probe amplification spectrum has a form of spectral doublet. Stronger pumping leads to the appearance of a single peak of the probe beam amplification at the transition frequency. The greater probe intensity results in an asymmetrical transmission spectrum with amplification at the blue wing of the absorption line and attenuation at the red one. Under high medium density, a broadband of amplification appears. The theoretical model is based on the solution of the Maxwell-Bloch equations for a two-level system. Different types of probe transmission spectra obtained are attributed to complex dynamics of a coherent medium response to broadband polychromatic radiation of a multimode dye laser.

A. Jabeoński