Transverse mode characteristics of a high power 1.3µm GaInAsP/InP buried crescent laser by the use of a dry etching process is described. With this technique, a single transverse mode (STM) yield as high as 95% was achieved. Transverse mode stability was confirmed after 1000 h aging at 50, 20 mW. A coupling efficiency into a single mode fiber as high as 63% was obtained.

The static characteristics of GaInAs(P)/GaInAsP quantum well laser diodes (QW LDs), with graded-index separate-confinement-heterostructure (GRIN-SCH) grown by metalorganic chemical vapor deposition (MOCVD), have been investigated experimentally in terms of threshold current density, internal waveguide loss, differential quantum efficiency and light output power. Very low threshold current density of 410 A/cm2, high characteristic temperature of 113 K, low internal waveguide loss of 5 cm-1, high differential quantum efficiency of 82% and high light output power of 100 mW were obtained in 1.3 µm GRIN-SCH multiple quantum well (MQW) LDs by optimizing the quantum well structure including confinement layer and cavity design. Excellent uniformity for the threshold current, quantum efficiency and emission wavelength was obtained in all MOCVD grown buried heterostructure GRIN-SCH MQW LDs. Lasing characteristics of 1.5 µm GRIN-SCH MQW LDs are also described.

The methods for the transverse mode control and temperature characteristics improvement in 850 nm oxide confined vertical cavity surface emitting lasers (VCSELs) were investigated. For transverse mode control, dielectric aperture was demonstrated to suppress higher order modes. Substitution of AlAs for Al0.9Ga0.1As in partial bottom DBR was demonstrated to reduce thermal resistance of the devices and to enable operation in high temperature of 85.

The effect of well number in 1.3 µm GaInAsP Graded-Index Separate-Confinement-Heterostructure Multiple-Quantum-Well (GRIN-SCH-MQW) laser diodes (LDs) is examined experimentally in terms of threshold current density Jth, differential quantum efficiency ηd and internal loss α. For LDs with cavity length L of 270 µm, Jth as low as 0.9 KA/cm2 was obtained with 5 quantum wells. ηd as high as 81% and α as low as 5 cm-1 were obtained with 4 quantum wells. Taking these parameters into account, 4 or 5 is calulated to be the optimum number of quantum wells for the present structure, which was confirmed experimentally. Light output power of 56 mW/facet with a narrow and circular output beam was obtained in a buried heterostructure (BH) GRIN-SCH-MQW LD entirely grown by Metalorganic Chemical Vapor Deposition (MOCVD). These results indicate that the use of a GRIN-SCH in a MQW LD of the GaInAsP/InP system is effective in the improvement of laser characteristics.

We fabricated 1.3µm AlGaInAs inner-stripe laser diodes (LDs), employing a GaInAsP waveguide layer and an n-InP current blocking layer. We compared the effects of the thickness of n-InP current blocking layer. A blocking layer with 500nm thick restricts the leakage current significantly. The inner-stripe LD was compared with the conventional ridge LD. I-L characteristics of both types of LDs were measured. Threshold currents of the inner-stripe LD and the ridge LD were 8.5 and 10.6mA, respectively. A threshold current of the inner-stripe LD is smaller than that of ridge LD. And the resistance of the inner-stripe LD was a few ohms lower than that of the ridge LD. Output power of 88mW was obtained at 200mA with 300µ m-long cavity. This was twice the power of a conventional ridge laser. The characteristic temperature of the inner-stripe LD was obtained 76 K from 20 to 85. We obtained a good linearity up to 100mA at 85. Therefore the inner-stripe LD has an advantage of high power devices.