Gouy Phase Shift of Self-focused q-Gaussian Laser Beams in Thermal Quantum Plasma and its Manifestation with the Berry Phase
N. Gupta
Gouy phase shift of q-Gaussian laser beams interacting nonlinearly with thermal quantum plasmas (TQP) with axially increasing density has been investigated theoretically. The Gouy phase shift also known as phase anomaly occurs at a fundamental level from position momentum uncertainty. A laser beam with finite cross-section and with some spatial amplitude structure behaves as if it is passing through a narrow slit resulting in spread in its transverse momentum. This transverse momentum spread then modifies the axial phase of the laser beam. Following variational theory, nonlinear partial differential equation for the field of laser beam has been reduced to a set of coupled differential equations for the evolution of beam width and axial phase of the laser beam. The equations so obtained have been solved numerically to see the effect of laser and plasma parameters on the evolution of beam envelope. Manifestation of Gouy phase shift with Berry’s phase also has been discussed in detail.
Keywords: Laser beam, q-Gaussian, Gouy phase shift, Berry phase, density ramp, thermal quantum plasma (TSP)