Raman Scattering And Stimulated Light Emission From Nanosized Silicon Crystals

В. С. Горелик, Anna D. Kudryavtseva, Nicolaii V. Tcherniega

Karl Grob

Lucia Florescu, Xiang Zhang

We study the stimulated Raman scattering (SRS) of light from an atomic system embedded in a photonic crystal and coherently pumped by a laser field. In our study, the electromagnetic field is treated classically and the atomic system is described quantum mechanically. Considering a decomposition of the pump and Stokes fields into the Bloch modes of the photonic crystals and using a multiscale analysis, we derive the Maxwell-Bloch equations for SRS in photonic crystals. These equations contain effective parameters that characterize the SRS gain, the nonlinear atomic response to the electromagnetic field, and the group velocity and that can be calculated in terms of the Bloch modes of the unperturbed photonic crystal. We show that if the pump laser frequency is tuned near a photonic band edge and the atomic system is carefully chosen such that the Stokes mode matches another photonic band edge, low-threshold, enhanced Raman amplification is possible. Possible physical realizations of SRS in photonic crystals are also discussed.

V. A. Zubov, M. M. Sushchinskiǐ, I. K. Shuvalov

В. С. Горелик, Anatoliy M. Negriyko, V. A. Orlovich +5 more

Stimulated Raman Scattering in globular photonic crystals and globular photonic glasses at different diameters of globules (250 – 400 nm) with embedded molecular liquids is studied under excitation by nanosecond or picoseconds laser pulses. Substantial decrease of Stimulated Raman Scattering threshold was observed. Such phenomenon was explained as the result of laser radiation field increase in globular photonic structures due to photonic density of states enhancement near the edges of photonic stop bands of photonic crystals and due to Mie resonance or whispering gallery modes effect revealing in photonic glasses. Stimulated Raman Scattering threshold lowering as a result of light capture in globular photonic crystals and photonic glasses opens the way to new efficient laser sources created on the base of composite globular photonic structures. Experimental data on spectra of Stimulated Raman Scattering in light and heavy waters are presented. As sources of exciting light the powerful ultra short solid state laser pulses with 532.0 nm wavelength and giant pulses of Ruby laser (694.3 nm) have been used. Several Stokes and anti-Stokes satellites were observed. Libration modes have been excited and resulted in some additional Raman bands at low frequency region and also as combining tones.

S. G. Pavlov, Nils Dessmann, Britta Redlich +6 more

We report on an optically pumped laser where photons are simultaneously generated by population inversion and by stimulated Raman scattering in the same active medium, namely crystalline silicon doped by bismuth (Si∶Bi).The medium utilizes three electronic levels: ground state [j1i: 1sðA 1 Þ in Si∶Bi], upper [j3i: 2p Æ ] and lower [j2i: 1sðEÞ] laser levels.The j1i ↔ j3i and j2i ↔ j3i transitions are optically allowed and the j1i ↔ j2i transition is Raman active.Lasing based on population inversion occurs between the states j3i and j2i, while Raman scattering benefits from the Raman-active transition.At high pump power the inversion-based stimulated emission j3i → j2i disappears, because electronic scattering from j1i to j2i via a virtual state dominates and the electrons are excited into j2i rather than into j3i.Starting as population inversion-based lasing, it ends as stimulated Raman scattering.Our model shows that such a competition occurs on the timescale of the 10-ps-long pump pulse.