Optimization of time-domain storage density in the presence of excitation-induced spectral diffusion

We present a technique to reduce the loss of storage capacity in time-domain optical memory in the presence of excitation-induced spectral diffusion. We applied this technique to a Eu(3+):Y(2) SiO(5)-based memory that utilizes frequency chirp for recording-retrieval and successfully stored 860 bits of data in a 40-MHz data channel. In comparison with the conventional chirp method under identical experimental conditions, the present technique offers an increase of a factor of ~2 in storage capacity with no measurable loss of signal fidelity. The results are interpreted in terms of the phase error accumulated during dephasing-rephasing and spectral diffusion on excited-state relaxation.