Optically Isolated Laser Modules

Fundamental design rules. necessary for optically isolated laser modules to perform satisfactorily in terrestrial and undersea lightwave cominunication systems, am discussed to assure a flexible and reliable overall design. The optically isolated laser modules have evolved based on a modularity concept which consists of a finite number (typically five) of stable building blocks. It is highly desired to design independent building blocks when the end specifications allow it. The building blocks are: 1) the package enclosure, 2) theThenno-Electric Cooler (TEC), 3) the laser and its platform, 4) the isolator assembly, and 5) the optical platform/fiber termination. One of the fundamental design rules is to keep the building blocks fully compatible and mechanically stable. Such an approach allows the designer to omit unnecessary module(s) or replace existing modules based on the customer's specifications for any new application(s). This results in cost effective designs and short design/models building intervals. In addition, the qualification of each building block does not have to be duplicated for every new laser module. This paper describes the design, assembly, and performance of two isolated laser packages utilizing all five building blocks.