This paper investigates the amount of doping concentration in silicon semiconductor using optical principle.  Both donor and acceptor impurities of n type and p-type silicon semiconductor materials are computed at wavelength of 1550 nm. During the computation of donor and acceptor impurities, both reflection and absorption losses are considered. Theoretical result showed that transmitted intensity through both n-type and p-type silicon structure increases with respect to doping concentration (10¹⁵ cm^-3 to 10²¹ cm^-3). It is also seen that transmitted intensity increases slowly up to 10²⁰ cm^-3 and then increases rapidly with the increase of doping concentration. Finally an experimental set up is proposed to estimate the doping concentration in silicon semiconductor.