Nonlocality and Bose Einstein condensation of light
In arXiv:1406.6250, Marcello Calvanese Strinati and Claudio Conti consider a microcavity made by a graded-index (GRIN) glass, doped by dye molecules, placed within two planar mirrors and study Bose-Einstein condensation (BEC) of photons. The presence of the mirrors leads to an effective photon mass, and the index grading provides an effective trapping frequency; the photon gas becomes formally equivalent to a two dimensional Bose gas trapped in an isotropic harmonic potential. The inclusion of nonlinear effects provides an effective interaction between photons.Thermal lensing effects and the resulting nonlocal nonlinearity are considered, and quantitatively compared with the reported experimental data (courtesy of Jan Klaers and Martin Weitz)
Last Updated (Thursday, 26 June 2014 20:11)
Nonlinear Optomechanical Pressure and Graphene
The mechanical effect of light has been the subject of the investigations of many scientists for more than three centuries but many questions are still open. In a recent manuscript (arXiv.org:1403.1948, Physical Review A 89, 033934, Editors' Suggestion), C. Conti and Robert W. Boyd predict that high energy ultrashort laser pulses may mechanically attract an object.
The effect is due to the fact that the velocity of a photon depends on the laser intensity. Because of the momentum conservation, also the velocity of an optically pushed object depends on the light intensity; hence the mechanical action of light can be all-optically controlled. This may be denoted to as the Nonlinear Balazs Block problem.
By using this nonlinear optical effect it may be possible to design experiments in which objects are attracted or accelerated by short pulses by an amount determined by pulse energy, temporal duration and spectral content. This nonlinear mechanical action is due to a property common to any sufficiently transparent material, the optical Kerr effect, that is, an intensity dependent refractive index. Conti and Boyd consider the specific case of a thin membrane of graphene, which has a very pronounced optical Kerr effect, and predict that is may be deformed as an optical sail by light. This may have a variety of applications for laser propulsion, and for laser controlled shaping of surfaces.
The authors report a theoretical analysis, which is validated by first principles simulations of the 3D+1 nonlinear Maxwell equations by using High Performance Computing (HPC) facilities within the CINECA-ISCRA initiative.
Last Updated (Thursday, 20 March 2014 06:55)