Study Transmission Laser on Short Distance by Singlemode Fiber Optic Based on Standard Deviation of Intensity

The relation between standard deviation of spot laser and the number of turns and the variety of bending diameters of single mode fiber optic has been studied in this work at short distance (10) cm from laser source. The single-mode fiber optic made from silica and turns over different diameter cylinders (3, 5 and l0) cm in one to ten turns. We capture image for spot laser for each turn by using digital camera connected by computer to calculate the standard deviation from algorithm program. The diode laser was used with wavelength (630- 680) nm, power (5 mW). The conclusion that increasing the bending diameter led to decrease standard deviation. Increasing number of turns led to decrease the standard deviation ofred color of spot laser. Three color bands (red, green and blue) were shown in our work. In first turn, the red color was dominant. Increasing number of turns led to put the green and blue colors be dominant. The best diameter of optical fiber is the high bending diameter (10) cm, where we get high coherence.