Static and Dynamic Characteristics of Ingan-based Laser Diodes

III-nitride-based laser diodes (LDs) are compact and efficient source of highly coherent continuous wave light for optoelectronic applications in the short-wavelength range (λ ∼ 400 nm). High peak-power and short-pulse generation in this spectral range has not yet been attempted and is of particular interest for applications such as, e.g., the next-generation of high-density optical data storage systems, ultraprecise nanoprocessing and fluorescence bio-imaging. More sophisticated devices like electrically-driven multisection LDs (MS-LDs) with a monolithically integrated saturable absorber section (AS) would lay the foundation for miniature portable femtosecond lasers combining the well known advantages of semiconductor LDs such as their easy manufacturing, the absence of mechanical alignments, their low cost, compactness and high potential for integrability. MS-LDs are fabricated by simply defining an electrically separated p-contact section that acts as a saturable absorber along the waveguide of a standard laser resonator. This way, the multiple-contacted sections on the laser cavity share the same active region and are therefore optically coupled. Additionally, the particular design of a MS-LD allows to modulate a posteriori the internal absorption of the device, affecting both its static and dynamic regimes, as it will be shown in this thesis. Under appropriate modulation conditions for the AS, the induced variations in the absorption coefficient can develop non-linearities in the system. Accordingly, the MS-LD can then be operated in stable and, more importantly, controllable dynamic regimes of self-pulsation (SP), Q-switching and active/passive mode-locking. The goal of the present study is to provide a detailed analysis of the system properties accounting for nitride specificities, to describe the static and dynamic mechanisms governing a GaN-based MS-LD and to present exhaustive interpretations of the experimental results and of the physical processes affecting the device performance. First, we design and grow high quality heterostructures with low defect density on free-standing GaN substrates. Achieving a high structural quality during the growth of InGaN multiple-quantum-well (MQW) is critical for the device performance. Using standard photolithography and dry etching techniques, we fabricate the MS-LDs with careful metallic deposition to define the cavity sections. Then, the LD structures are cleaved and tested on a probe station to define the optical emission characteristics. In particular, the trends of the main different observables (e.g., optical gain and loss distributions, lasing threshold current, absorption coefficient, pulsating frequency,...) and their respective issues are identified and commented. These measurements provide an important feedback for optimizing