Photon-Gated Spectral Hole-Burning in a Polymer Doped with a Mixture of Several Zn-Benzoporphyrin Derivatives

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.