A model for laser marking of thin organic data storage layers by short intense pulses

Abstract

A mathematical model is developed to describe the pit formation process in thin (∼0.1 μm) organic layers induced by short (<100 ns), intense laser pulses. The basic premise is an ablation-driven viscous flow, in which the reactive pressure gradient due to polymer decomposition causes fluid motion. Contrary to the case of thick layers (∼1 μm) and long (∼500 ns), weak pulses, here surface tension gradients are shown to be too small to promote material flow in the short time span of laser exposure. The derived closed-form expressions for temperature profile and pit contour allow expedient calculation of threshold energies and prediction of functional relationships among imposed (e.g., pulse energy and width) and measured (e.g., pit width) system variables. Model predictions compare favorably with experimental observations of such interrelations.