1.3 micron polarization insensitive tapered waveguide devices

This work discusses the details of MOCVD growth, characterization and fabrication of 1.3{dollar}mu{dollar}m tapered waveguide polarization insensitive devices. Compressive, tensile and lattice matched material was first developed. Broad area lasers with 3 compressive strained quantum wells (QWs) have a threshold current density (J{dollar}sb{lcub}rm th{rcub}{dollar}) of 234A/cm{dollar}sp2{dollar} and with 3 tensile QWs have a J{dollar}sb{lcub}rm th{rcub}{dollar} of 277A/cm{dollar}sp2{dollar} which are comparable to the best values reported in the literature. Polarization insensitive devices with active regions containing both tensile and compressive QWs were then developed using an edge photoluminescence characterization technique. This technique is useful in matching the wavelengths of the TE and TM modes which is an important requirement for obtaining dual polarization characteristics. Broad area lasers fabricated from these materials demonstrated dual polarization lasing characteristics and the amplifiers obtained after AR coating the facets had polarization insensitivity of about 1dB between the TE and TM modes.; Tapered waveguide buried heterostructure devices with mixed quantum well (MQW) active regions were then developed using a combination of wet and dry ECR etching which is much simpler than any of the techniques used today for obtaining spot-size transformation. Threshold currents as low as 20mA were obtained for the MQW devices. Single mode far-field FWHM angle reduction of about {dollar}12spcirc{lcub}-{rcub}15spcirc{dollar} were obtained in both the lateral and vertical directions. This results in a 4dB improvement of the coupling efficiency of the tapered end over the untapered end of the device. A waveguide loss calculation based on experimental data was done to find the excess loss due to the tapered section of the waveguide.; InGaP based 0.98{dollar}mu{dollar}m and 0.8{dollar}mu{dollar}m short wavelength broad are lasers were also studied. The effect of the waveguide layer on the device characteristics was examined in the case of the 0.98{dollar}mu{dollar}m lasers. Low threshold current densities of 72A/cm{dollar}sp2{dollar} were achieved for these devices. The effect of strain on the gain characteristics was studied for 0.8{dollar}mu{dollar}m lasers. A low threshold current density of 239A/cm{dollar}sp2{dollar} was achieved in these devices.