Patent ID: 7449278

Claim:
A multilayer optical recording medium comprising: a first recording layer for recording or reproducing information by using a first light beam having a center wavelength λ1; a first photochromic layer provided on said first recording layer; a first optical waveguide layer provided on said first photochromic layer for guiding to said first photochromic layer a second light beam having a center wavelength λ2 different from said center wavelength λ1; a second recording layer provided on said first optical waveguide layer for recording or reproducing information by using said first light beam; a second photochromic layer provided on said second recording layer; and a second optical waveguide layer provided on said second photochromic layer for guiding said second light beam to said second photochromic layer; wherein the reflectance of each of said first and second photochromic layers to said first light beam can be repeatedly increased by irradiation with said second light beam and can be repeatedly decreased by stoppage of said irradiation.