In fiber optic communications, a single mode fiber optic cable, also known as fundamental mode or single mode, is a fiber designed to transmit only single mode light (transverse mode).The mode is a possible solution to the Helmholtz equation for the wave, which is obtained by combining Maxwell's equations and boundary conditions. These modes define the way the wave propagates in space, i.e. how the wave is distributed in space. Waves can have the same mode but different frequencies. This is the case with single mode fiber optic cable,we can have waves of different frequencies but the same mode,which means they are distributed in space the same way, which gives us a beam of light. Although light travels parallel to the length of the fiber, it is often referred to as a transverse mode because its electromagnetic oscillations occur perpendicular (transversely) to the length of the single mode fiber optic cable.The 2009 Nobel Prize in Physics was awarded to Kao for his theoretical work on single mode fiber optic cable.The G.652 and G.657 standards define the most widely used forms of single mode fiber optic cable.