The ridge waveguide laser diode is theoreticallyanalyzed and experimentally fabricated in this thesis.The waveguide properties are investigated by using theeffective refractive index approximation. The opticalconfinement, defined as the fraction of the opticalpower containing in the waveguiding layers, is obtainedby this technique. The analyses of the fundamentaltransverse heterostructures of DH, LOC and SCH arecarried out and consequently yields the optimal valuesof active, waveguiding and cladding layer thickness

such values providing the single transverse mode. Inorder to obtain the single lateral mode, the optimalvalues of residual upper-cladding layer thickness (t)and ridge width (w) are determined by analyzing theeffect of cladding layer thickness. The experimentalfabrication of ridge waveguide laser with GaAs/AIGaAsDH structure and an 0.2 pm GaAs active layer isdemonstrated by the Liquid Phase Epitaxy (LPE)technique. The ridge width of 4 pm and residualthickness of 0.35 pm are established by wet-chemicallyetching and thereby provide the difference of 0.002lateral index step for single-spot beam profile(TE(,oo)) The threshold current ranging from 120 to 150mA and the differential quantum efficiency ranging from2.5 to 3.6% were achieved from the fabricated chipswith 500-600 (...)m cavity length.