Mirrorless parametric oscillation in an atomic Raman process

Abstract

We investigate experimentally and theoretically the onset of parametric oscillation in a single-pass atomic Raman scattering process without the optical feedback. We find that this Raman oscillation effect is due to the coherent buildup of the atomic spin waves, and therefore the threshold of the Raman pump power for the onset of the oscillation depends on the decoherence time of the atomic spin waves and the Raman coupling constant but is not sensitive to the loss of the Stokes field, unlike the effect of amplified spontaneous emission. A simple theory of atomic Raman process fits the experimental results very well. The long decoherence time of the atomic spin waves in the atomic Raman process leads to a threshold power as low as a few hundred microwatts.

Quantum memories: emerging applications and recent advances

“…In the limit where – for example in far-off-resonant Raman protocols [ 106 , 113 , 129 ] – the Raman coupling strength for FWM becomes comparable to that of the memory and hence FWM can be a significant source of noise. In these systems other methods, such as polarization selection rules [ 149 ], phase-matching in a dispersive medium [ 99 ], or non-colinear geometry [ 150 ], can be used to minimize the detrimental effects of FWM.…”

Coupling of four-wave mixing and Raman scattering by ground-state atomic coherence

“…In particular, it may be used in different regimes, starting from the single-photon and single-excitation spontaneous regime as in the DLCZ protocol [3,4], through the linear gain regime [20,21] and even in the nonlinear gain-saturation regime [22][23][24]. In the two latter cases, macroscopic ground-state coherence is generated [25]. The generated coherence and the number of scattered photons will be highly random but correlated.…”

Mirrorless optical parametric oscillator inside an all-optical waveguide

“…Along with the experimental demonstration of MOPO in thermal atomic vapor for the case of non-degenerate FWM [16], there has been many theoretical studies on the generated photon pairs [17][18][19][20][21]. The phenomenon has also been reported for Raman process in hot atomic vapor [22].…”