Time- and frequency-domain hybrid optical memory: 16-kbit data storage in Eu^3+:Y_2SiO_5

Abstract
We propose and demonstrate a novel type of frequency-selective optical memory that writes and reads the data in both the time domain and the frequency domain. Temporal 16-bit data were stored by accumulated-photon-echo bit-by-bit storage at 103 frequency addresses within the inhomogeneous line of the 7F05D0 transition of Eu3+:Y2SiO5, which yields a total memory capacity of 1.6 kbits in a single spot of 240-μm diameter. The keys to the success of this experiment are this material’s long dephasing time and lack of spectral diffusion.