We consider two-photon bound states which may be excited in a planar waveguide filled with a self-focusing Kerr material. These bound states are the quantum analogs of the classical light bullets which form under the combined effects of self-focusing, diffraction, self-phase-modulation, and anomalous group-velocity dispersion. A variational approach is used to establish a threshold condition on the strength of the nonlinearity for the existence of the bound state, and a gedanken experiment is proposed to outline the principles for creation and detection of this quasiparticle.

• Received 13 July 1992

DOI:https://doi.org/10.1103/PhysRevA.47.3330