The design of 1550nm InGaAsP/InP Fabry-Perot ridge waveguide laser diode for optical communication applications had been achieved by using advanced laser diode simulator (ALDS).The coating had been deposited on both sides front facet and back facet by using AR (Anti Reflection) and HR (High Reflection) coating o respectively. The AR coating had been selected to be a single layer of ZnS with a thickness about 0.12 urn for getting a reflectivity about 10% on the front facet, while the HR coating had been selected to be two pairs of the Al2O3/Si stack each layer with quarter wavelength thickness for getting a reflectivity about 90% on the back facet. The calculations had been done by using MATLAB 7 software program. The effects of the reflectivity on the properties of laser diode like the output power, the threshold current, the external efficiency, the output spectrum, the side mode suppression ratio (SMSR) value and the far-field pattern had been investigated by using advanced laser diode simulator (ALDS).