An optical analysis disc includes grooves defining corresponding laser-readable tracks and trigger marks that identify respective target regions on the disc. The apparatus for generating a digital pulse width modulation signal includes a random period signal generator, a noise shaping unit, a duty ratio quantizer, and a PWM counter. The apparatus can also include a waveguide with surrounding structure that can be adjusted to produce the desired half power beamwidth. The hierarchy also includes striping operations that create and maintain storage volume stripes comprising sub-volumes andor extents.