Fiber optic or Patchcord is transmission media which is made of fiber glass and plastic that use refraction light in transmitting data. The light source used is a laser because it has a very narrow spectrum. Fiber transmission media optic has replace media era copper on the grounds that the fiber optic has advantages, namely: information is transmitted to the capacity (bandwidth) high, because purely made of glass and plastic, the signal is not affected on electromagnetic and radio-frequency waves. While copper media can be affected by electromagnetic wave interference and wireless media affected by radio frequency. With these advantages, the optical fiber has been widely used as a backbone telecommunications network. Perbedan single mode and multi mode is that the single mode core size is small, the laser beam source, unlimited bandwidth, and long distances (> 60 km), while multi-mode core has a size larger, laser light source or Light Emitting Diodes (LED), limited bandwidth, a distance of approximately (300-500 m).