Two dimensional FDTD modeling of direct semiconductor laser read/write systems

摘要

In this paper we describe how finite difference time domain (FDTD) calculations can be used in the modeling of extremely short external cavity (ESEC) lasers used in modern optical data storage systems. We study the operation of direct semiconductor laser read/write heads that utilize either a conventional edge emitting laser or very small aperture laser. The storage medium is assumed to be a first-surface-recorded phase change (e.g. SGT) disc. The external cavity is formed between the laser's front facet and the disc. The length of the ESEC is typically 0.1 to 1.0 microns. By using FDTD we can study the behavior of the electric field in the ESEC in detail, taking into account the vector field effects resulting from the three-dimensional nature of the data marks and laser apertures. We calculate the distributions of electric field amplitudes, power flow and absorption in/near the external cavity. In addition, we calculate the effective reflectance spectrum of the ESEC and use this data as input into a phenomenological laser model to simulate the readout signal, i.e. the laser's output power and/or wavelength.