Application of Spectral Hole-Burning in Combination with Holographic Recording Techniques

Several spectroscopic techniques make use of the nonlinear properties of solids in order to obtain high spectral resolution. Spectral hole-burning as one of them additionally offers the potential for applications in high density optical data storage. The ratio of inhomogeneous to homogeneous linewidth of the molecule 2,3-Dihydroporphine (Chlorin) doped into a polymer is in the order of 104 at liquid Helium temperatures. Excitation of molecules with a narrow band dye laser results in a tautomeric photochemical reaction and the formation of a spectral hole, representing digital information. In addition the spatial dimensions can be used in order to store two dimensional patterns or pictures. The use of holographic recording and readout techniques provides the possibility of background free defection. The formation of an absorption and refractive index grating — governed by the Kramers-Kronig relation — allows one to influence the diffraction properties of the hologram by controlling phase and frequency.