P. Di Trapani et al., Observation of optical vortices and J(0) Bessel-like beams in quantum-noise parametric amplification, PHYS REV L, 81(23), 1998, pp. 5133-5136
We show that optical vortices and J(0) Bessel-like beams can be generated v
ia traveling-wave linear parametric amplification of the quantum noise, in
the absence of external seeding or resonator feedback. The shot-to-shot flu
ctuations in the topological charge of the amplified signal are driven by t
he quantum-noise seed. [S0031-9007(98)07767-9].