A method and apparatus models one or more electromagnetic field modes of a waveguide. The method includes sampling a two-dimensional cross-section of the waveguide.
An optical fiber includes a cladding, a first core, and a second core. At least one of the first core and the second core is hollow and is substantially surrounded by the cladding.
An optical sensor includes an optical coupler. The optical sensor further includes a photonic bandgap fiber having a hollow core and an inner cladding generally surrounding the core. The photonic bandgap fiber is in optical communication with the optical coupler.