Atomic Processing of Optically Carried RF Signals

Abstract

Rare earth ions embedded in crystals are natural high-quality-factor resonators that can be used for processing optically-carried broadband radio-frequency signals. This chapter focuses on the radio-frequency spectrum analysis function and describes different architectures that are designed to reach tens of gigahertz instantaneous bandwidth with submegahertz resolution. Various approaches are considered. The active material may act as a spectral buffer memory. Instead one may store a processing function inside the crystal. The latter may then operate either as a frequency-to-angle converter or a frequency-to-time transformer. All those architectures have been explored experimentally. To meet the specific requirements of these processors, frequency agile lasers have been developed. These keynote devices are described in detail.

Narrow inhomogeneous and homogeneous optical linewidths in a rare earth doped transparent ceramic

“…This has been used recently in the field of quantum memories 12 to demonstrate storage of entangled photons 13,14 , entanglement of crystals 15 , and high efficiency quantum storage 16 . The narrow spectral holes that can be burned into rare earth absorption lines have also enabled continuous analysis of optically carried radio frequency signals 17 , ultrasound optical tomography 18 or laser frequency stabilization 19,20 . Ceramic materials could be an alternative to single crystals in these applications, offering unique possibilities for flexible shaping and composition, but only if the rare earth linewidths, especially the homogeneous linewidth, are sufficiently narrow.…”

Dephasing mechanisms of optical transitions in rare-earth-doped transparent ceramics

“…Their possible applications include radio frequency spectral analysis [3], laser stabilization [4], enhanced ultrasound tomography [5], signal processing, and quantum memory devices [1,6]. In all of these, a key element is the fact that trivalent rare-earth ions possess extremely narrow optical homogeneous linewidths [7,8].…”

Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

“…1 Due to these properties, such materials are of great interest for application in quantum information processing (QIP) [2][3][4][5] and spectral filtering. The latter includes radio frequency signal analysis, 6,7 highly stable laser-locking, 8,9 and ultrasound optical tomography (UOT). 10,11 Recently, rare-earth doped transparent ceramics have been suggested as an alternative class of materials for these applications, 12 as for lasers 13 and scintillators.…”