Superfluidity of coherent light in self-focusing nonlinear waveguides

Ze Cheng

Ze Cheng

We study the thermodynamic properties of coherent photons in self-focusing nonlinear waveguides. The equation of the superfluid state of photons has been derived. There is a transition temperature [Formula: see text], above which the photon gas is in the coherent state, but below which the photon gas is in the superfluid state. At [Formula: see text], the photon system undergoes a first-order phase transition from the coherent to the superfluid state. To determine the fugacity [Formula: see text] and the transition temperature [Formula: see text] of the photon gas, we numerically solve the equation of the superfluid state of photons. The fugacity [Formula: see text] is a monotonically decreasing function of temperature [Formula: see text] and light intensity [Formula: see text]. The transition temperature [Formula: see text] is a monotonically decreasing function of light intensity [Formula: see text].

Omar Boughdad

John E. Bjorkholm, P. W. E. Smith, W. Tomlinson +3 more

We experimentally demonstrate a fundamentally new type of intrinsic optical bistability that requires no resonant optical cavity. Operation is based on mutual self-focusing of counterpropagating laser beams in a nonlinear medium. We propose and experimentally demonstrate a fundamentally new type of optical bistability. 1 The operation of this new class of devices is based on self-focusing of light; the feedback required for bistability is provided by an apertured retroreflector. These devices exhibit intrinsic bistability (the feedback is optical) and are related to nonlinear waveguide devices proposed earlier. 2 Self-focusing occurs when a light beam having a nonuniform spatial profile (such as a Gaussian laser beam) and sufficient intensity propagates through a nonlinear medium having an intensity-dependent index of refraction. 3 Previously proposed devices that exhibited

Lene Vestergaard Hau

V G Kukushkin

The problem of transformation of the parameters of a Gaussian light beam in a nonlinear medium with a complex susceptibility is solved. The parabolic approximation for the wave equation is employed. The results obtained can be used in the design of resonators and waveguides with nonlinear components. A study is made of the influence of the complex part of a nonlinear susceptibility of a substance on the threshold conditions for the self-focusing in the case of resonant absorption in a two-level system. It is shown that in this case it is possible to expect self-focusing of radiation on the low-frequency side of an absorption line.