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Title: Carrier injection based reflective optical switch in silicon-on-insulator
Author: Owens , Nathan Philip
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2013
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Optical switches that reflect light through the process of total internal reflection offer many advantages when compared with other systems such as interferometric and resonant devices as compact stl1lctures can be produce~ with a wavelength- and polarizationindependent response. As well as these benefits, they are immune to temperature variations and tolerant to imperfections which can be imparted into a structure from the manufacturing process. To reflect light efficiently requires the creation of an abl1lpt change in refractive index which is difficult to achieve in silicon based material systems operating through carrier injection due to the long diffusion length of caniers. The aim of this project was to design, fabricate and test a canier injection reflective optical switch in the silicon-on-insulator material system for routing applications within a telecommunication network. To achieve the objective, a reflective optical switch design has been developed which consists of a symmetric Y-branch rib waveguide with twinp-i-n diode arrangement. A confinement barrier is incorporated into the structure which is created by the standard CMOS process of creating a deep isolation trench that prevents caniers from diffusing outside the modulation region and at the same time allows the passage of a propagating mode. Computer simulations have predicted the devices are capable of attaining low TE/TM crosstalk values of -20dB for a power consumption below 22.5m W. Models of the ultrathin oxide barrier which is used in the deep isolation trench for electrical isolation have indicated that a layer with a thickness of2nm can achieve the lowest TE/TM losses of 0.05 and 1.77dB, respectively. Prototype devices have been successfully constl1lcted by using equipment typically found in academia cleamoom environments. Processing was undertaken by using techniques such as chemical mechanical polishing and cryogenic reactive ion etching. The ultrathin oxide has been formed in nitric acid for the confmement banier. Testing has demonstrated the prototypes are capable of directing light from an input port to a particular output port by applying a forward bias to one of the modulation regions. 111
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available