In order to reduce the threshold current of a GalnAsP/InP surface emitting junction laser, a SiO2/metal mirror which provied high reflectivity has been introduced. The minimum threshold was reduced down to 18 mA at 77 K which is about a half of the previous case (35 mA). The operating temperature was raised up to 10.

Mesa structures have been investigated to optimize a buried-heterostructure (BH) for a GaInAsP/InP surface-emitting (SE) laser regrown by metalorganic chemical vapor deposition (MOCVD), and it has been found that a square mesa top pattern of which the sides are at an angle of 45 to the 011 orientation is suitable. A 1.3-µm GaInAsP/InP square buried heterostructure (SBH) SE laser with this mesa structure has been demonstrated and low-threshold CW oscillation (threshold current Ith=0.45 mA) at 77 K and low-threshold room-temperature pulsed oscillation (Ith=12 mA) have been obtained.

In order to reduce the threshold current of GaInAsP/InP surface emitting (SE) laser, we introduce a flat surface circular buried heterostructure (FCBH), which has merits of both planar buried heterostructure (PBH) and buried heterostructure with a SiO2 mask (BH), into GaInAsP/InP SE laser. Its minimum threshold current was 20 mA at 77 K, which provide better result than previous PBH-SE lasers or BH-SE lasers grown with a SiO2 mask.