Design Techniques for Hardened Fiber Optic Receivers

Hardened design techniques have been developed for fiber optic receivers that consider transient ionization and permanent damage effects. The results show that there is a fundamental trade-off between optical sensitivity and transient ionization hardness that depends primarily on the bit rate and the physical characteristics of the detector. In addition, various input stage designs and modulation methods can be considered in order to optimize both the optical sensitivity and radiation hardness. Radiation test results are included for three different receiver designs that were tested in five different radiation environments. The results show good agreement with design equations that were developed for different types of input stages, and demonstrate the hardness levels that can be achieved with currently available optical and semiconductor components.