Optical Pumping

Thomas R. Carver

Kambiz Abedi, H. Taleb

In this paper, optimal design of a pumping scheme for achieving the best gain and phase response in quntum--dot semiconductor optical ampliers is investigated.For the rst time, the dynamic response of the quntum-dot semiconductor optical amplier is evaluated under three dierent pumping schemes, known as optical pumping, electrical pumping, and electro-optical pumping.Simulation results show that the shortest gain recovery time in quntum-dot semiconductor optical ampliers can be achieved under the electrical pumping scheme.However, under the optical pumping and electro-optical pumping schemes, the quntum-dot semiconductor optical amplier represents a shorter phase recovery compared to the electrical pumping scheme.We found that a sub-nanosecond phase recovery in the quntum-dot semiconductor optical amplier can be achieved under the OP and electro--optical pumping schemes, which can never be achieved under the electrical pumping, because of the slow carrier dynamics of the carrier reservoir.Also, it was found that the gain recovery process in an optically pumped quntum-dot semiconductor optical amplier can be signicantly accelerated at cryogenic temperatures.This result demonstrates the superiorities of the optical pumping scheme over the electrical pumping and electro-optical pumping schemes at low temperatures, where both the gain and phase recovery times of an optically pumped quantum-dot semiconductor optical amplier are drastically decreased.

Junmin Wang, Qiangbing Liang, Jing Gao +3 more

Two schemes of Doppler-free high-resolution velocity-selective optical-pumping atomic spectroscopy, named single-resonance optical pumping (SROP) and double-resonance optical pumping (DROP), are performed and characterized with room-temperature cesium vapor cells. Due to velocity-selective optical pumping from one hyperfine fold of ground state to another via one-photon excitation in SROP or cascade two-photon excitation in DROP and decay processes thereafter, the atomic population variation of one hyperfine fold of ground state is indicated by SROP and DROP spectra by using of the transmission of the probe laser which is usually frequency locked to a cycling hyperfine transition. As a result, SROP and DROP spectra often have flat background and higher signal-to-noise ratio. Therefore, SROP and DROP spectra are very useful for measurement of the dressed-state splitting of ground state with an alkali atomic vapor cell, precise measurement of hyperfine splitting of alkali atomic excited states, frequency references for laser frequency stabilization, two-color MOT, and so on.

Claude N. Cohen-Tannoudji, Alfred Kastler

Bien Chann, Earl Babcock, L. W. Anderson +1 more

Circularly polarized light propagating at an angle to the external magnetic field does not optically pump atoms to full transparency under conditions common to spin-exchange optical pumping experiments. This causes excess absorption of the pumping light that can significantly reduce the efficiency of the optical pumping process even for angles of a few degrees.

Robert A. Bernheim, Ernst K. Franke