Coherent four-wave mixing of light pulses

Erik Brekke, Laura Alderson

Nathaniel B. Phillips, Alexey Vyacheslavovich Gorshkov, Irina V. Novikova

We study the modification of a traditional electromagnetically induced transparency (EIT) stored-light technique that includes both EIT and four-wave mixing (FWM) in an ensemble of hot Rb atoms. The standard treatment of light storage involves the coherent and reversible mapping of one photonic mode onto a collective spin coherence. It has been shown that unwanted, competing processes such as four-wave mixing are enhanced by EIT and can significantly modify the signal optical pulse propagation. We present theoretical and experimental evidence to indicate that, while a Stokes field is indeed detected upon retrieval of the signal field, any information originally encoded in a seeded Stokes field is not independently preserved during the storage process. We present a simple model that describes the propagation dynamics of the fields and the impact of FWM on the spin wave.

Wei Cao, Erika R. Warrick, Ashley P. Fidler +2 more

Coherent narrow-band extreme-ultraviolet (EUV) light is generated by a near-resonant four-wave mixing (FWM) process between attosecond pulse trains and near-infrared pulses in neon gas. The near-resonant FWM process involves one vacuum-ultraviolet (VUV) photon and two near-infrared (NIR) photons and produces new higher-energy frequency components corresponding to the $ns/nd$ to ground-state $(2{s}^{2}2{p}^{6})$ transitions in the neon atom. The EUV emission exhibits small angular divergence (2 mrad) and monotonically increasing intensity over a pressure range of 0.5--16 Torr, suggesting phase matching in the production of the narrow-bandwidth coherent EUV light. In addition, time-resolved scans of the NIR nonlinear mixing process reveal the detection of a persistent, ultrafast bound electronic wave packet based on a coherent superposition initiated by the VUV pulse in the neon atoms. This FWM process using attosecond pulses offers a means for both efficient narrow-band EUV source generation and time-resolved investigations of ultrafast dynamics.

Pavel A Apanasevich, Anatoly A. Afanas'ev, V.V. Dritz +1 more

Andrei I. Maimistov, Yu. M. Sklyarov

Li Deng, M. G. Payne, W. R. Garrett

We present a time-dependent calculation for four-wave mixing using a combination of long, short, and time delayed laser pulses in the context of electromagnetically induced transparency. Two transform limited nanosecond lasers are used to create a highly coherent mixture of the ground state and an excited state via a two-photon process. Once the induced transparency is established, a laser with short pulse length is injected after a suitable delay to generate four-wave mixing. We show that the wave mixing process is phase matched for all detunings, and with appropriately selected atomic coherence and populations, near 100% photon flux conversion efficiency can be obtained, independent of the intensity of the short pulse laser. In addition, we show that for small detunings for the short pulse laser, the four-wave mixing field travels with the speed of light in vacuum and suffers no pulse distortion even though the medium is highly dispersive at the frequency of the generated wave. These advantages open a door for future applications of the scheme for highly efficient, very stable UV generation.