Characteristics of distributed Bragg reflector active optical filters

The transfer function characteristics of distributed-Bragg-reflector (DBR)-based active optical filters are described. Small and large signal characteristics are presented, and a variety of nonlinear effects obtained in the large signal regime such as gain saturation, frequency pulling, and wavelength domain bistability are demonstrated. While these nonlinear effects may be detrimental to conventional filter applications, they may possibly be explored for new approaches in wavelength domain logic, switching, and routing. The filter can also be used in a reversed configuration. Compared to the characteristics described, the small signal transmission transfer function remains unchanged but the input power at which the nonlinear effects take place is increased by 20-30 dB. This is due to the much reduced reflected power inside the filter cavity. At the same time, however, the noise power added to the amplified signal is also significantly increased.<>