Lasing by superradiance of laser-cooled ions

K. Hayasaka

F. G. Major

Gagik Yu. Kryuchkyan, B. Kneer

We propose a simple model of an ion-trap laser: A single two-level ion confined to a harmonic trap, subjected to resolved-sideband laser cooling in the presence of external noise, and coupled strongly to an optical cavity. The lasing of the cavity mode results from the quantized treatment of the ion's motion, and occurs when the cavity is tuned to frequencies of the vibrational sidebands located below the frequency of the cooling laser.

F. G. Major

Eyob Alebachew Sete, Anatoly A. Svidzinsky, Yuri V. Rostovtsev +4 more

It was shown some time ago that when the excitation of an ensemble of two-level atoms is swept in the direction of lasing, so that atoms are prepared in the excited state just as the radiation from previously excited atoms reaches them, the resulting laser amplifier is “highly anomalous” and yields superradiant emission without population inversion. We here show that transient gain in a three-level system has common features with Dicke superradiance and can yield strong extreme ultraviolet lasing in, for example, He atoms (at 58 nm) or He-like ions such asB3+(at 6.1 nm).

Christoph Hotter

A cold atomic gas with an inverted population on a transition coupled to a field mode of an optical resonator constitutes a generic model of a laser. For quasi-continuous operation, external pumping, trapping and cooling of the atoms is required to confine them in order to achieve enough gain inside the resonator. As inverted atoms are high-field seekers in blue detuned light fields, tuning the cavity mode to the blue side of the atomic gain transition allows for combining lasing with stimulated cavity cooling and dipole trapping of the atoms at the antinodes of the laser field. We study such a configuration using a semiclassical description of particle motion along the cavity axis. In extension of earlier work we include free space atomic and cavity decay as well as atomic dipole-dipole interactions and their corresponding forces. We show that for a proper choice of parameters even in the bad cavity limit the atoms can create a sufficiently strong field inside the resonator such that they are trapped and cooled via the superradiant lasing action with less than one photon on average inside the cavity.