A Superradiant Amplifier

Fritz Haake, M. I. Kolohov, Claude Fabre +2 more

Gyu Ug Kim, Sang Soo Lee, Jae Won HAHN

A superradiant and amplified spontaneous transition pulse is obtained from an iodine photodissociation laser amplifier which uses i-C3F7I as an active molecule and is pumped with a flashlamp (full width at half maximum=3 μs). We have observed a sharp leading pulse of superradiance whose rise time is less than 50 ns, and the amplified spontaneous emission follows the superradiance during the pumping flash. By measuring the population inversion density in the active medium of the amplifier, we have obtained the threshold condition for the superradiance to take place. Also, the buildup time and peak intensity of the pulse are measured as a function of the flashlamp input energy. By placing a reflecting mirror at a varying distance (from 173 to 673 cm) behind the amplifier, we have found a periodic intensity fluctuation in the superradiance; the period (Δt) depends linearly on the distance (d), i.e., Δt=2d/c, where c is the light velocity.

A. I. Makarov, A. K. Potemkin

An investigation was made of the energy, spectral, angular, and temporal characteristics of superradiance emitted by a multistage neodymium glass amplifier with a gain of ~107. Superradiance was found to affect significantly the operation of the amplifier only when the gain reached ~107– 108.

Akhil Deswal, Navdeep Arya, Kinjalk Lochan +1 more

We identify low-acceleration conditions under which the Unruh effect manifests as an early superradiant burst in a collection of excited atoms. The resulting amplified Unruh signal is resolved from the inertial signal both in time and intensity. We demonstrate theoretically that these conditions are realized inside a subresonant cavity that highly suppresses the response of an inertial atom, while allowing significant response from an accelerated atom as, owing to the acceleration-induced spectral broadening, it can still couple to the available field modes. The setup thus selectively amplifies the modified field fluctuations underlying the Unruh effect into an early superradiant burst. In comparison, the field fluctuations perceived inertially would cause a superradiant burst much later. In this way, we simultaneously address the extreme acceleration requirement, the weak Unruh signal, and the dominance of the inertial signal, all within a single experimental arrangement.