Concentration of indium in indium gallium arsenide (InxGa1-xAs) is computed at optical signal having wavelength 589 nm . Reflection as well as absorption losses are considered to obtain the transmitted intensity. Analytical result showed that reflectance increases with increasing of indium concentration, where absorbance decreases with the same concentration. An experimental set up is designed to find out the transmitted intensity, which leads to the computation of concentration of indium in indium gallium arsenide semiconductor. Present simulation result showed that transmitted intensity increases exponentially (R2 = 0.9802) with respect to indium concentration, which varies from 0% to 30 %. Keywords: InGaAs, reflectance, absorbance, transmitted intensity.
