Crack propagation 1 Cut-off frequencies 1 Frequency spacing 1 Graphene 1 High data rate 1 High data-rates 1 Higher mode 1 MATLAB 1 Microwave propagation Optical communication 1 Optical properties 1 Optical- 1 Quadrature phase shift keying 1 Single mode 1 Slab waveguides 1 Wave numbers 1 Wave propagation 1 Waveguide 1 Waveguides 1 cut-off frequency 1 frequency spacing 1 graphene 1 microwave propagation 1 slab dielectric 1