A Polarization Insensitive Semiconductor Optical Amplifier with Integrated Electroabsorption Modulators

As optical access to the loop becomes more advanced, using emerging fiber to the loop (FTTL) architectures, and with the possible use of wavelength division multiplexing (WDM) to enhance transmission capacity and networking flexibility, it is important to consider new components that may be useful as building blocks for the upcoming local access networks. Obviously, for FTTL applications, low cost is an important prerequisite for components that are not widely shared. This may require uncooled operation, ease of packaging, and perhaps integration of opto-electronic devices. One of the new FTTL- WDM architectures that was recently demonstrated is RITE-Net [1,2], which is based on a WDM signals from a central office sent downstream to a remote node, and then to the local optical network unit (ONU). The carrier wavelength is modulated at the ONU using an on site optical modulator and returned upstream to the central office. One parameter that effects the performance is the insertion loss of the modulator. To improve the power budget of the system, it might be useful to employ a component that has integrated modulators and a semiconductor optical amplifier (SOA) resulting in a modest fiber to fiber gain rather than a large insertion loss. The proposed component can also enable WDM networks where frequency conversion and/or signal equalization over a large dynamic input range is required. It may be useful to integrate two modulators, so that one can be used for data encoding and the other for power level equalization.