Tunable TM modes in a slab waveguide including a graphene-dielectric multilayer structure

TM modes in a slab waveguide with a graphene-dielectric multilayer structure as the core and different ordinary materials as the cover and the substrate are investigated. The group velocity of TM modes can be positive, negative, and zero. The standstill of electromagnetic waves at different key waveguide thickness, which depend on the gate voltage, is successfully realized. The gate voltages or mode numbers have a greater influence on the zero and negative group velocities, but have a little influence on the positive group velocity. Besides, the power flow can be positive, zero and negative values at the key waveguide thickness. Similarly, the gate voltages or mode numbers have a little influence on the zero and negative power flows when the frequency is less than 7.0 THz, but they have a big influence on both positive and negative power flows when the frequency is larger than 7.0 THz. More interestingly, as the frequency increases from 9.0THz to 10.0THz, superpower flows of TM modes reach a dynamic balance both the core and the cladding. The tunable superpower flow properties will benefit us to construct a novel full optical switch and an ultra large optical power memory.