OBJECTIVE OF SEMINAR List important operational parameters of switching devices. Comparison among different switching devices on the basis of these parameters.
OPERATIONAL PARAMETERS(1) Operating wavelengths LED and AlGaAs LASER have wavelength between .8 and .9 um. However advantage may be gained at the detector from generating source with operating wavelength above 1.1 um as both fiber attenuation and dispersion is reduced.(2) Linearity LED and Photodiodes has linear response while Injection LASER response is non linear.(3) Low cost The simple construction of LED and photo detector reduce the cost of construction but Injection LASER has high construction cost.
OPERATIONAL PARAMETERS(CONT.)(4) Reliability LED does not exhibit catastrophic degradation and has proven less sensitive to gradual degradation than Injection LASER. Photo detectors are reliable at room temperature.(5) Temperature dependence The LED characteristic is less effected by temperature than corresponding characteristic of ILD. The temperature dependence is maximum for photo detectors.(6) Drive circuitry LED and ILD does not require driver circuit, this is due to lower driver current and reduced temperature dependence but characteristics of photo detectors changes with temperature therefore compensation of temperature effect is necessary.