Highly efficient diode-pumped alkali-vapor amplification with near-extreme-limit gain.

We report high-efficiency optical amplification with near-extreme-limit gain from a diode-pumped Cs vapor cell. We used wavelength-division multiplexing to couple 852 nm pump and 895 nm seed lasers to achieve nearly overlapping spatial modes in the Cs vapor cell. We investigated the amplification factor as a function of the focal length of the lens focusing on the combined pump and seed signals and determined the optimal focal length under our experimental conditions.

Photon-pair generation from a chip-scale Cs atomic vapor cell.

The realization of a narrowband photonic quantum source based on an atomic device is considered essential in the practical development of photonic quantum information science and technology. In this study, we present the first step toward the development of a photon-pair source based on a microfabricated Cs atomic vapor cell. Time-correlated photon pairs from the millimeter-scale Cs vapor cell are emitted via the spontaneous four-wave mixing process of the cascade-type 6S-6P-8S transition of Cs.

Stimulated four-wave mixing in the cascade-type atomic system of a warm Cs atomic ensemble.

We investigate stimulated four-wave mixing (FWM) in the 6S-6P-8S open transition of a warm Cs atomic ensemble. Despite the absence of the two-photon cycling transition, we measure high-contrast FWM signals in the 6P-8S transition between the upper excited states according to the frequency detuning and powers of the coupling and driving lasers. The FWM light generation in the upper excited states is interpreted as the FWM phenomena induced by the driving laser of the 6S-6P transition from the cascade-type two-photon coherent atomic ensemble with the coupling and pump lasers.