Coherent optical data processing

K. Terry Stalker

Philip Hemmer, M. S. Shahriar, M. K. Kim +2 more

We experimentally demonstrate time-domain storage and retrieval of amplitude- and phase-encoded optical data, using Raman coherent population trapping, despite the loss of information about absolute optical phases that occurs as a result of the dissipative nature of the process. In this Raman optical storage process homogeneous decay of the optical coherence does not prevent interference between time-separated fields, thus relaxing the requirement for long-lived optical coherences.

S. H. Lee

Miao Zhu, C. Michael Jefferson, Wm. Randall Babbitt

When a sequence of temporally modulated optical waveforms illuminate an inhomogeneously broadened absorbing medium, the resultant optical coherent transient output signal's represents the cross-correlation or convolution of the input temporal waveforms.1 The projected performance characteristics of coherent transient processors include data rates greater than 10 GHz, time-bandwidth products far in excess of 10,000, and the ability to fully process both amplitude and phase modulated waveforms.1,2 Previously it was assumed that the input data stream and pattern stream must both be shorter than the absorbing transition's homogeneous dephasing time and must both be reentered in order to process longer or multiple data streams.1 It has recently been proposed that patterns could be permanently stored in an inhomogeneously broadened solid and that input data streams of indefinite length could be continuously processed in real time without the need to reenter the input pattern.3,4 In this paper, we present a proof of concept demonstration of an optical coherent transient continuous correlator.

B. V. K. Vijaya Kumar

Mads Tønnes, F. Schüller, Etienne Cantin +4 more

Abstract Aiming at delivering a highly available service, the French national optical fiber link network is run mostly unmanned and automatically, with the help of a global supervision. However, at a year scale, missing data are seemingly unavoidable. Here, we present a first study of the uncertainty of coherent fiber links with missing data. We present the tools to assess statistical properties for processes which are not strictly stationary, and a simulation of optical fiber links depending only on a handful of parameters. We show how missing data affects the phase-coherent optical fiber links, and how to mitigate the issue with a fill-in procedure that preserves the statistical properties. We apply the method for a 5 years-long data set of a 1410 km long fiber link. Second, we apply the method to the case of optical clock comparisons, where the downtimes of the optical clocks degrade the coherence of the links. We show that our methodology of processing the missing data is robust and converges to consistent mean values, even with very low uptimes. We present an offset and uncertainty contribution from the French fiber network of 2.4 (9.0) × 10−20, that is an improvement by a factor 5 as compared to a processing without taking the effect of missing data into account.