Design and simulation of plasmonic devices for application in photonic and electronic integrated circuits

Abstract

newline xiv newlineABSTRACT newlinePlasmonics is a new technology which provides the advantages of fast speed of photonics and ultra-tiny size of electronics in a single platform. Surface Plasmon Polaritons are the information and data carriers used in Plasmonics. They are regarded in a same way like electrons are used to carry data in electronics and photons in photonics. Basically, SPPs are the EM waves which are tightly confined and used in the development of ultra-small devices for photonic integrated circuits. Plasmonics have the advantage that optical signals are processed at nano meter scale. Size of plasmonic based devices are even smaller than the wavelength of light that are incident on the devices, this is because plasmonic devices overcome the diffraction limit, which was very difficult to achieve in case of different standard optical methods. Plasmonics is capable of offering high bandwidth and low power consumption to its devices. newlineThere are many kinds of waveguiding technologies present for confining and manipulating light inside the plasmonic devices, but Metal dielectric metal configuration is extensively used because it offers strong confinement to light. Due to this, tremendously fast, effectual and tiny dimension components which include modulators, switches, filters, amplifiers and lasers can be realized. There is another advantage of using MDM plasmonic waveguides that presence of metal in upper and lower part reduces the need of external electric contacts for applying voltage which also offers easy integration. The low resistance due to the metal layers and small capacitance due to smaller size provides high speed operation and reduce RC time constants which does not limits the performance of device. Small size of devices provides additional advantage of low drive voltages because due to tiny sized devices large electric fields can manipulate external signals even at small voltages. These small operating voltages and small capacitance leads the device towards low power operation. newlineInvolvement of active materials inside the plasmonic devices are gaining much attention because when active materials are sandwiched as core inside the MDM waveguides, then devices offers more confinement of light as active materials shows large refractive index change when comes in contact with the externally applied fields and opens the ways to achieve more efficient devices with large modulation ratios and less propagation losses. These kinds of active devices can be integrated smoothly with the current nanoelectronics and nanophotonic devices with new heights of integration and features. newlinexv newlineIn this thesis the main focus is to develop ultra-compact active plasmonic devices which can be integrated with the future nanophotonic circuits with large extinction ratios for modulation and small losses. Different kind of active materials are used for developing different nano plasmonic devices like modulators, sensors, filters and switches. For developing these all devices different principle effects which operates on the change in refractive index of devices when some external field is applied are investigated and devices are designed and simulated on basis of those electrically controlled effects. newlineFive resonant devices are designed and simulated in this thesis, which works on different principles of refractive index change by using different active materials for their operation. All devices have shown good modulation depth and low loss with the nanoscale footprints. These all devices are capable to operate in the telecommunication range and can easily integrated with on chip photonic and electronic circuits due to their ultra-small sizes and simple construction geometries. All the proposed devices have shown good Quality factors and Figure of merit which also opens a way for Wave Division Multiplexing applications as well. newlineThis technology is also appropriate for cheap mass production and possibly may be used with electronic circuits on the same chip. Both active and passive devices are of great importance because they both are used to manipulate light in hybrid photonic/electronic circuits which are CMOS compatible.