TABLE OF CONTENTS The extra requirements of packaging optoelectronic rather than just electronic devices are challenging [1], and real packages involve numerous compromises between different aspects of performance, as well as manufacturing costs. To make the best of a well designed device, DFB-laser chips must be packaged so as
to protect them from the environment;
to enable monitoring of the optical output;
to provide thermal heat sinking;
to provide a rigid and stable optical coupling platform to a fibre (or other output system); and then
to allow electrical interfaces between the appropriate 'DC' and modulated RF current supplies and the laser.
The need to obtain stability and precision of the mechanical alignment in laser packages often results in a metal package with glass-to-metal seals for electrical connecting pins, and glass windows or carefully designed fibre interfaces. Rapid progress is being made with ceramic packages incorporating stripline interfaces, and some laser packages are now partly injection moulded. The variability of package and laser parameters is large, and the parameters relevant to any particular laser and its package need to be measured appropriately and then used in any modelling. The values quoted here are for a typical metal package with glass-to-metal seals.
Figure A10.1 indicates such typical parasitic circuit components which need to be considered in evaluating the overall frequency response of a laser to direct modulation. The glass-to-metal seal of a package may present a lead-through capacitance C p~0.5 pF, and the fine gold or aluminium...
