Temporal and spectral hybrid interference from phase transition of Eu3+/Pr3+: YPO4 and evolution of amplifier and multiplexer

Highlights: • The temporal and spectral oscillation originating from the interference among the FL and SPFWM signals. • The frequency of oscillation is directly proportional to the interference. • The self Rabi-oscillation is robust and prominent with resonant excitation when compared with off-resonant excitation. • The interference oscillation observed in Pr³⁺: YPO₄ is significantly higher than Eu³⁺: YPO₄. We study the temporal and spectral oscillation originated from the interference between the fluorescence (FL) and spontaneous parametric four-wave mixing (SP-FWM) signals. The FL and SP-FWM are generated from different phases of Eu³⁺ or Pr³⁺ doped YPO₄ under the nonlinear SP-FWM process. We discuss and compare the spectral interfering oscillations and self-Rabi oscillations controlled via multiple phase transitions (hexagonal-phase and mixed-phase) of Eu³⁺: YPO₄ and Pr³⁺: YPO₄. The coexistence mechanism of interference and self-oscillations in time domain is also investigated. Further, we discuss the cross-Rabi oscillation in correlated light beams, which evolves from FL signal (having Sinc profile) to SP-FWM (having Cosine profile) in the hybrid signal regime. Based on these results, we have realized wavelength division multiplexing, and temporal amplifier with the temporal interference being controlled by the gate position, and frequency detuning. Our experimental results provide a technique to achieve higher channel equalization ratio about 85%.