Analytic Technique For Active Mode-Locked Fiber Lasers

In this work, Aِmplitude modulation mode-locked fiber laser isstudied,by using Ytterbium Doped Fiber Laser, single mode fiber,operating with 1055 nm wavelength with 976 nm optical pump and AMMode-Locked by optical modulators. A grating pair is used to compensatethe normal dispersion. The effect of both normal and anomalous dispersionregimes on output pulses are investigated. Master equation of the Modelockingfiber laser is introduced .Pulse shapes for both dispersion regimesare assumed after modifying (Ginzburg-Landu equation) GLE which isessentially Generalized Nonlinear Schrödinger equation GNLSE and byapplying the moment method ,a set of five rate equations for pulse energy,pulse width ,frequency shift ,temporally shift and chirp ,which solutionsdescribed the pulse from round trip to the next and how they approach tosteady state values. To solve these equations numerically fourth order,Runge-Kutta method is performed through Mat-Lab 7.0 computer program.Result shows that, the output pulse width from the AM mode-Lockedequals to τ=0.8ps in anomalous and τ=1ps in normal regimes. The studyshows the stability of working in anomalous dispersion regime is betterthan normal regime

MANUFACTURE OF FIBER OPTIC SENSORS TO MEASURE THE PH WATER

A fiber-optic pH sensor based on evanescent wave penetration is presented. Evanescent wave penetration is generated by removing the clad and contact the core with the solution. Testing samples were perpetrated by add a strong acid (HCL) or a strong base (NaOH) at distilled water to produce different value of pH (from 4 to 13). To determine the absorption or transmission of the evanescent waves, that generate after where obtained on appropriate calibration curve to determine a wide range of pH, by using pH indicators. Where using methyl red, by add fixed amounts of this dyes to the water samples were obtained on samples with colors vary with pH values. Calculate the transmission and absorption with draw a relationship between the transmissions or absorption with the pH values, to obtain on suitable curves, considered as calibration curves. Calibration curve for methyl red is best, where extends (from 4 to 12) for pH value. Can calculate the pH value for any water sample to tested, by the add the same ratios of the organic dyes it used