Investigation of Large Signal Effects onCascaded Travelling Wave ElectroAbsorption Modulator (CTWEAM)Performance and Optimization

• Main Author: Islam, Hamidul A. B. M.
• Format: Others
• Language: English
• Published: KTH, Skolan för informations- och kommunikationsteknik (ICT) 2012
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107719

In this thesis work large signal model of cascaded travelling wave electroabsorption modulator (CTWEAM) has been studied. The effect of input modulating voltage, input optical power, biasing voltage, and circuit parameters on bandwidth, extinction ratio and overshooting of this modular carefully investigated. It has been also investigated the sensitivity of the transit time delay and the length ratio of active segment and microstrip line over the total length on the performance of the modulator. As the modulating voltage, input optical power and biasing voltage are increased then the bandwidth, extinction ratio and overshooting are also increased until certain value (except for modulating voltage) after that increasing of input optical power and biasing voltage the bandwidth, extinction ratio and overshooting are decreased. At 1.1 V biasing voltage, 14 mW input optical power and only 0.4 V(p-p) modulating voltage the cascading modulator has 3dB bandwidth, extinction ratio and overshooting 110 GHz, 4 dB and 0.2 dB respectively. It has been shown that at the same biasing voltage and input optical power but at 1 V(p-p) modulating voltage the cascading modulator has 119 GHz 3dB bandwidth, 10.9 dB extinction ratio and 0.47 dB overshooting that could be applicable for telecommunication. It has been seen that the microwave reflection loss is -10 dB at 100 GHz to perform the device on the above mentioned values. It has been shown that the cascading modulator to perform on the above mentioned values, the p-doped mesa structure has changed from rectangular to mushroom shape which has 0.69 Ω-mm, total active segment length is 990 μm where first, second, third and fourth active segment have 11%, 10%, 22% and 56% length over the total active segment length. Since the cascading modulator performance has been studied on large signal model, the results have been obtained from this thesis work would be the crucial for optimum designing and fabrication of the cascading modulator to apply in real life application.