Vernier enhanced Mach Zehnder interferometer for dissolved methane detection
MetadataShow full item record
In this thesis the theory describing a vernier enhanced Mach Zehnder interferometer for detecting dissolved methane is discussed. A method for effectively simulating photonic components, with features ranging from centimeter to nanometer scale using COMSOL is demonstrated. The method is then used to simulate the behaviour of a vernier enhanced sensor. Based on the simulations, a methane sensitive sensor using the vernier concept is presented. The proposed sensor has a limit of detection as low as 9.34 10^(-6) RIU and overall sensitivity of 326 um/RIU, and should detect concentrations of dissolved methane less than 50 nM . The feasibility of producing a prototype in NTNU Nanolab have also been investigated. Both straight waveguides, ring resonators and five MZI's with Y-bends has been fabricated on an silicon-on-insulator (SOI) platform. The processes used includes plasma enhanced chemical vapor deposition (PECVD), electron beam lithography (EBL), inductively coupled plasma reactive ion etch (ICP-RIE) and a scanning tunneling electron microscope (S(T)EM) for characterization. Some of the fabricated components are also tested in an optics lab. Based on characterisation using S(T)EM, the SOI platform with a thermally grown oxide layer is concluded to be the favourable choice for fabricating a prototype sensor in the future.