Date of Award
Campus Access Thesis
Master of Science (MS)
The significant scattering loss in noble metals has been recognized as a major limiting factor in the field of plasmonics where many optical processes either linear or nonlinear are expected to be enhanced. One interesting idea to circumvent this issue is the use of doped semiconductors as alternative plasmonic materials which are known to have lower momentum scattering rates. Such an idea has received much attention recently in the hope that stronger optical field enhancement can be produced with the alternative plasmonic materials. However, up to now there has not been any experimental evidence to support this idea. Some have attributed this lack of support to technical challenges in material quality and argued that once the fabrication techniques are improved, the anticipated benefits can be realized in due time. In this thesis, we will discuss from the theoretical point of view why the lower scattering rate in doped semiconductors doesn’t lead to stronger field enhancement. We specifically analyze doped InGaAs in mid infrared where it does behave as a plasmonic material with sufficient doping and compare its optical field enhancement with that of gold. Our analysis concludes that when it comes to optical field enhancement noble metals always outperform doped semiconductors with lower losses. To support our conclusion, we also present the numerical simulation results of localized and propagating surface plasmon polaritons (LSPR and SPPs). We show that noble metals with their higher losses actually yield stronger optical field enhancement and have longer propagation length when constructed into plasmonic waveguides than alternative plasmonic materials.
Hsieh, Wen Ting, "Comparative Analysis of Noble Metals and Doped Semiconductors for Optical Field Enhancement in Infrared" (2018). Graduate Masters Theses. 504.