Theoretical studies of high power long wavelength InGaNAs quantum well laser diode for pumping raman amplifier / Mohd Faiez Ali

This thesis studies the effects of Nitrogen (N) fraction, quantum well (QW) number, presence and absence of GaNo.01Aso.99 barrier and thicker GaAs waveguide layers based on three device designs (device A, B and C) of Ino.32Gao.68No.007Aso.993 QW laser diodes (QWLDs). These effects are theoretically studied using sophisticated simulator of RSoft LaserMOD in order to deliver a good quality long wavelength and high power Ino.32Gao.68NyAsi-y QWLD suitable for pumping Raman amplifier (RA). N fraction is varied from 0.007 to 0.022 with a step of 0.003, number of QW is elevated from 1 to 3, conventional GaAs barriers are replaced with the GaNo.01Aso.99 barriers, and the GaAs waveguide thickness is varied from 380 ran to 2000 nm. It was found that by increasing N fraction up to 0.022 the lasing wavelength h is significantly elongated from 1.2400 urn to 1.6416 urn, 1.2378 urn to 1.5892 urn and 1.2127 urn to 1.2790 ^m for device A, B and C respectively while the output power (Pout) is slightly degrades from 4.618 W to 3.103 W, 4.5609 W to 2.0093 W and 8.748 W to 8.975 W. The shifting of h is caused by the reduction of the Ino.32Gao.68NyAsi-y band-gap when higher N fraction is introduced into all devices. The best N fraction is then determined as 0.007 for all devices. Furthermore Pout degradation and shifting of h is suggested to have strong relationship with the phenomenological relationship constant valued at 99.5 eV, 88 eV and 18 eV for device A, B and C respectively. Increasing the number of QW was found to prominently increased optical confinement factor (OCF) rather than increasing Pout in all devices. The best number of QW is determined as 2 for all devices which yields OCF of 1.8029 %, 1.84008 % and 1.58900 % for device A, B and C respectively with maximum Pout of 5.102 W, 2.281 W and 1.509 W taken at various current injection level. The used of GaNo.01Aso.99 barrier and thicker GaAs waveguide was found to enhance Pout and X\. A maximum Pout of 5.454 W, 2.440 W and 2.286 W are recorded for device A, B and C respectively along with h of 1.2404 urn, 1.2379 um and 1.1538 um. Also by using thicker GaAs waveguide layer, the internal loss (ai) of the devices can possibly be reduced to amplify Pout. The optimum GaAs waveguide thickness for device A, B and C is then determined at 1600 nm, 800 nm, and 1100 nm respectively. Based from the simulated outputs, an appropriate correlation between N fraction, number of QW, GaNo.01Aso.99 barriers and thicker GaAs waveguide layers of the Ino.32Gao.68NyAsi-y QWLD towards the Jth, Pout and X\ is proposed.