Photonic Devices using Coupled Plasmonic Structures

The loss-confinement trade-off is the key limitation that prevents realistic utilization of plasmonic components in photonic integrated circuits. Although coupled-mode plasmonic structures can help alleviate the trade-off, stringent symmetry requirements limit the fabrication tolerance and the optical functionalities that can be supported. In this dissertation, a coupled hybrid plasmonic waveguide (CHPW) capable of supporting both long-range propagation and subwavelength confinement is presented as a versatile platform for designing integrated optical devices. The supermodes guided by CHPWs are formed via the coupling of surface plasmon polariton (SPP) and hybrid plasmonic waveguide (HPW) modes across a common metal layer. By manipulating the destructive interference between these highly dissimilar plasmonic modes, it is shown that the modal field overlapping the lossy metal region can be minimized without being significantly redistributed. As such, experimental realization of CHPW shows propagation loss and mode area of only 0.07dB/um and 0.002um^2 respectively. As these attributes are fabrication-tolerant and wavelength-insensitive, CHPW micro-ring resonator with loaded Q-factor of 3276 is also demonstrated. The advantage of CHPW as a device platform is that it can also support active functionalities. Specifically, the metal-semiconductor interface where the SPP portion of the supermode is guided can serve as an internal photoemission-based Schottky photodetector. Experimentally, a 20um CHPW photodetector demonstrates responsivity of 80mA/W and sensitivity ofPh.D.2021-10-30 00:00:0