A low-loss rectangular-passband multiplexer including a three-arm interferometer coherently connected to a waveguide grating router, resulting in a passband substantially of type N=3, without intrinsic loss. By relying on a standardized data format and communication structure, a general architecture can be created and used to dynamically build and reconfigure interaction between both similar and dissimilar security products. A spacer is used between the substrate and the thermal conductor. The invention is also to a nanoparticle or plurality of nanoparticles, each nanoparticle comprising a core having a largest dimension less than about 10 nm; and a metal layer substantially surrounding the core and having a largest dimension less than about 200 nm. A range \u03b1 in which each of the grooves is formed is larger than a range of 15 degrees around the axial line and is smaller than a range of 180 degrees around the axial line. The disk control apparatus recovers the data to the designated point on the basis of a backup disk and a journal disk.