We precisely measure the time-energy correlation of broadband, spontaneously generated four waves mixing, and demonstrate surprising intensity dependent splitting of the correlation in both time and frequency and coupling effects between the domains.
We measure the time-energy correlation of broadband, spontaneously generated four wave mixing (FWM), and demonstrate novel time-frequency coupling effects; specifically, we observe a power-dependent splitting of the correlation in both energy and time. By pumping a photonic crystal fiber with narrowband picosecond pulses we generate FWM in a unique regime, where broadband (>100nm), sidebands are generated that are incoherent, yet time-energy correlated. Although the observed time-energy correlation in FWM is conceptually similar to parametric down conversion, its unique dependence on pump intensity due to self and cross phase modulation effects, yields spectral and temporal structure in the correlations. While these effects are minute compared to the time duration and bandwidth of the FWM sidebands, they are well observed using sum frequency generation as a precise, ultrafast, wide-bandwidth correlation detector.
We measure the time-energy correlation of broadband, spontaneously seeded four-wave mixing (FWM), and demonstrate time-frequency coupling effects; specifically, we observe a power-dependent splitting of the correlation in both energy and time. By pumping a photonic crystal fiber with narrowband picosecond pulses we generate FWM in a unique regime, where broadband (>100 nm) sidebands are generated that are incoherent, yet time-energy correlated. Although the observed time-energy correlation in FWM is conceptually similar to parametric down-conversion, its unique dependence on pump intensity due to self- and cross-phase-modulation effects yields spectral and temporal structure in the correlations. While these effects are minute compared to the time duration and bandwidth of the FWM sidebands, they are well observed using sum-frequency generation as a precise, ultrafast, wide-bandwidth correlation detector.
Abstract Induced photon correlations are directly demonstrated by exploring two coupled nonlinear processes in an integrated device. Using orthogonally polarized modes within an integrated microring cavity, phase matching of two different nonlinear four‐wave mixing processes is achieved simultaneously, wherein both processes share one target frequency mode, while their other frequency modes differ. The overlap of these modes leads to the coupling of both nonlinear processes, producing photon correlations. The nature of this process is confirmed by means of time‐ and power‐dependent photon correlation measurements. These findings are relevant to the fundamental understanding of spontaneous parametric effects as well as single‐photon‐induced processes, and their effect on optical quantum state generation and control.
We have studied theoretically a phase-conjugate ultrafast modulation spectroscopy (PCUMS) in a Doppler-broadened system. The pump beams consist of two frequency components which drive two different transitions. It is found that the four-wave-mixing (FWM) signal exhibits damping oscillation as the relative time delay between two pump beams is varied, from which the energy-level splitting can be deduced. We have considered the cases that pump beams have either narrow band or broadband linewidth and found that for both cases a Doppler-free precision in the measurement of the energy-level splitting can be achieved. The advantage of PCUMS is that the energy-level splitting between states can be widely separated. Finally, the relationship between PCUMS and other Doppler-free techniques in frequency and time domains has also been discussed.