Output Characteristics of III-V Quantum Dot Injection Microdisk Lasers

Semiconductor microdisk lasers developed using III-V epitaxial materials are widely studied during the last decade due to the bright prospectives coming from high quality circular cavity. The threshold and spectral characteristics of microlasers have been studied in sufficient detail, but the issue of the output power of such lasers has not been addressed, just as the features of the light-current characteristics have been poorly studied. The complexity of this issue is associated with the high Q factor of the disk resonator, and therefore the low level of radiative loss. In addition, the peculiarities of the farfield radiation pattern of a disk laser make the usual methods to measure light-current dependences incomplete, in which part of the information about the microlaser radiation is lost due to the fact that the laser radiation has a complex nature in the lateral and vertical directions. In this work, we provide a comprehensive overview on the main parameters influencing output power and efficiency progress of III-V quantum dot injection microdisk lasers. We discuss fundamental concepts related to the output power limitations in the quantum dot disk lasers. We demonstrate improving of the far-field diagram of disk lasers with small deviation of the cavity shape from circular. Limaçon-shaped microlasers were used to increase output power and wall-plug efficiency. We also summarize methods to control the output power and to improve thermal characteristics of a small disk lasers.