We have fabricated integrated twin-guide (ITG) corner reflector (CR) InGaAs-AlGaAs-GaAs laser diodes for the wavelength of 980 nm. In ITG laser diode the coupling between active laver and output waveguide is very strong so that the operation of ITG laser diode is sensitive to variations in epitaxial growth structures and material parameters. We have investigated the dependencies of ITG-CR lasers on these parameters. In situ laser reflectometry system was used to control epitaxial thickness and etching depth, precisely. Optical dispersion parameters based on Afromowitz' formula was applied to in situ laser reflectometry.