New possibilities of obtaining spectral holes narrower than natural line width

Wolfgang Zinth, Martin C. Nuss, W. Kaiser

William Smyth, S. Swain

We consider a single two-level atom driven by the output from a degenerate optical parametric oscillator. For squeezing bandwidths of the order of the natural atomic width and smaller, we report remarkable spectral profiles for the scattered light, including the existence of a narrow hole at line-centre. Under appropriate conditions, the spectrum may be both subnatural and narrower than the spectrum of the incident field, a phenomenon which does not depend upon strong coupling. To explain the role of the classical or non-classical nature of the driving field plays, we consider an alternative system which enables the atom to be driven by an arbitrary bandwidth light field with arbitrary two-photon correlations. Both numerical and analytic solutions are employed to provide physical insight. Surprisingly, spectral narrowing does not require squeezing: narrowed spectra appear for driving with a blackbody field. Then the atomic fluorescence can be expressed as the product of the atomic response with the incident spectrum. The resulting narrowing is maximized for incident bandwidths of the order of the natural width. However, the narrow hole at line-centre does require a non-classical driving field. For ideal squeezing, the fluorescence at line-centre vanishes. We test how robust the effects are to changes in experimentally pertinent factors such as the solid angle of coupling.

Eric S. Maniloff, Felix R. Graf, Hansruedi Gygax +4 more

Marcel Tschanz, Aleksander K. Rebane, Urs P. Wild

We demonstrate a new integrated narrow-band spectral filter which consists of a planar waveguide covered with a thin polymer film donated with molecules liable to persistent spectral hole-burning (SHB) at liquid helium temperature. We show that such a device performs as a miniature programmable narrow-band spectral filter with a transmission bandwidth less than 1 angstrom. In contrast to currently used techniques, the frequency resolution of a SHB filter is limited, in first place, by the width of the homogeneous zero-phonon lines of the chromophore molecules, and not by the geometrical dimensions of the device.

B. Luo, Jean‐Pierre Galaup

Photochemical spectral hole-burning (PSHB) has attracted particular attention in the past decade because of its potential for frequency domain optical storage. In order to apply PSHB to a practical optical memory, the material should have high burning temperature, high thermal stability, erasability and high frequency multiplexing. Two ways are possible to increase the storage density: one is to narrow the homogeneous line width, the other is to broaden the inhomogeneous line width. In previous works, the larger inhomogeneous line width (greater than 1,000 cm–1) has been reached in polymethylmethacrylate (PMMA) doped with two kinds of Zn-benzoporphyrin derivatives with roughly the same hole-burning efficiencies [1]. In this paper, the authors investigate systematically the optical properties of Zn-benzoporphyrin derivatives, their hole-burning mechanisms, thermal stability and electron-phonon coupling in cellulose acetate (CA) and in PMMA matrices. The choice of CA was motivated mainly by the fact this polymer allows to prepare samples with excellent optical quality.

W. Bennett, Veniamin P. Chebotayev, J. W. Knutson