Buried-Heterostructure laser diode is described, theoretically analyzed, and experimentally fabricated. The waveguiding properties and laser threshold conditions are analyzed using the effective refractive index approximation. Near equilibrium LPE growth method, which is useful in growing extremely thin layer, and Zn diffusion technique for enhancing the property of the ohmic contact are described in detail. Typical BH laser, $350 \times 10 \times 0.2 \mu{m}^3$, has 1.2V of cutin voltage and 150 mA of threshold current. With fine lithography equipment and by applying current-confining geometry to this laser, the threshold current can be more reduced.