Simulation of Traveling Wave Electroabsorption Modulators for Phase Modulation

Abstract: Electro-Absorption Modulators (EAMs) have been instrumental in achieving ultrafast modulation speeds of over 100 Gb/s, and in particular, segmented Travelling-Wave (TWEAMs) designs offer excellent compatibility with standardmicrowave technology due to their characteristic impedance being closer to 50. The TWEAM device fabricated as part of the European Project HECTO, has been succesful is field trials at 112 Gb/s using On-Off Keying (OOK). Achieving phase modulation using a TWEAM offers not only significant improvements over OOK in terms of higher bit rate, but also a great advantage against other phase modulators that use electro-optic effects which need much stronger drive signals and also present issues with chip-integration. The existing model for the TWEAM has been modified to incorporate a variable delay line to simulate enhanced electro-optic effects in the active quantum well layer. Simulations were performed for Binary and Quadrature Phase Shift Keying, and 8-Quadrature Amplitude Modulation. Clear constellation diagrams are obtained at 10 Gb/s with Error Vector Magnitude of around -19 dB at 10 Gb/s and -10 dB at 50 Gb/s. Results from this thesis emphasize the need for further optimization of the model and fabricating a TWEAM that is capable of advanced modulation formats.