This book is collection of research work done at Masters level at Egerton University. From the research findings it was found out that bends, pressure and temperature variations have an effect in the quality of the output signal. The books is organized in of papers and gives a clear research findings on the effect of temperature variation, pressures and bend on the quality of the output signal on Cw Laser on single mode fiber. It also brings a very clear explanation what needs to be done upon this effect. Further research is suggested and more recommendation is given to optical fiber technician. Its suitable for postgraduate level studies in optical fiber communication technology.