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In this work, the operating characteristics of quantum dot (QD) lasers with asymmetric barrier layers (ABLs) are studied. Several different cases are examined, in particular: 1) Effect of excited states on static and dynamic operating characteristics Within QDs, in addition to the lasing ground state, carriers can be captured into excited states, where they then decay into the ground state. This excited-state-mediated capture impacts the operating characteristics, limiting the maximum output power and modulation bandwidth. Three separate cases are considered: only indirect capture with electron-hole symmetry, both direct and indirect capture with electron-hole symmetry, and both direct and indirect capture of electrons but only indirect capture of holes. The impact of different parameters on the operating characteristics is studied, with values for maximizing the output power and modulation bandwidth being found. In addition, it is found that parasitic recombination in the active region in the space between QDs causes the output power to saturate at high injection currents for the cases of indirect capture for both electrons and holes and indirect capture for holes but direct and indirect capture for electrons, although the presence of the ABLs causes it to reach saturation at much lower currents. 2) QD laser with only a single ABL To be effective, the materials for ABLs must be carefully chosen to ensure that the band edges properly align to allow one carrier to enter the active region while preventing the other from overshooting it. Due to this requirement, it may arise that a suitable material only exists for one ABL but not the other. The performance of a QD laser with only a single ABL is considered and compared to a conventional QD laser. Specifically, the output power and characteristic temperature are calculated. While the single ABL laser only offers a negligible increase in output power compared to the conventional laser, it offers a considerable increase

The MOCVD growth mechanism of InAs QD was first explored. By optimizing the InAs QD growth parameters, including growth temperature, V/III, growth rate, and capping process, highly uniform QDs have been achieved with a dot density of about 5.5E10cm-2. Room temperature PL characterization on the QDs shows a 50 nm FWHM for the ground state. A high-quality InGaP thick layer under low temperatures was also developed as the cladding layer for the laser structure. High-performance FP cavity QD laser on GaAs substrate was first demonstrated with state-of-the-art performance. The broad-area laser without facet coating shows a single facet power of 200 mW; the short narrow-ridge laser without facet coating shows a high wall-plug efficiency of about 30%. To enable a QD laser on Si, the GoVS template was developed. Combining the technology of aspect ratio trap, thermal cycle annealing, and strain layer superlattice, the GoVS sample has achieved a low threading dislocation density (4E6cm-2) and a surface roughness of 2.7 nm. The full laser structure was grown on the GoVS sample with AlGaAs as the lower cladding layer and low-temperature InGaP as the upper cladding layer. The laser on Si has shown a decent device performance at room temperature and continuous-wave operation.

The age of the Internet brings unprecedented challenges to the communication networks. The ever non-stopping increase of link traffic in data center demands wide bandwidth, densely integrated yet low cost optical transceiver circuits. For on-chip communication, copper interconnections are increasingly challenged by the stringent link budget presented by today's multi-core processing units. As an alternative, On-chip optical interconnect is being actively pursued due to its energy efficiency and scalability. Addressing these challenges brings photonic integrated circuit closer and closer to the processing electronics. Si photonics will undoubtedly be the key to achieving such feat due to its CMOS compatibility and its ability to offer compact, low-loss, and versatile photonic circuitry. Yet, silicon, being a non-direct bandgap material, need to be integrated with III-V material to create on-chip light source. One of the approaches to achieve this is by epitaxially growing quantum dot laser stack on silicon substrate. Over the past few years, we, together with our colleagues around the world, have made significant improvements in the material quality of the epitaxially grown quantum dot lasers. Yet, little efforts have been taken in integrating the grown quantum dot material with passive waveguide structures.In this thesis, we first dive into the gain characteristics of the quantum dot laser material. A novel measurement technique is adopted to allow studying the unique properties of quantum dot active region under the influence of different growth techniques. Such knowledge provides insights on how to further improve the performance of quantum dot lasers. With sufficient understanding of the quantum dot material, we designed a novel device platform which enables integration of quantum dot active region with passive waveguide structure. By doing so, complex laser cavities such as DBR lasers, mode-locked lasers, and SGDBR tunable lasers are demonstrated in this platfor

The age of the Internet brings unprecedented challenges to the communication networks. The ever non-stopping increase of link traffic in data center demands wide bandwidth, densely integrated yet low cost optical transceiver circuits. For on-chip communication, copper interconnections are increasingly challenged by the stringent link budget presented by today's multi-core processing units. As an alternative, On-chip optical interconnect is being actively pursued due to its energy efficiency and scalability. Addressing these challenges brings photonic integrated circuit closer and closer to the processing electronics. Si photonics will undoubtedly be the key to achieving such feat due to its CMOS compatibility and its ability to offer compact, low-loss, and versatile photonic circuitry. Yet, silicon, being a non-direct bandgap material, need to be integrated with III-V material to create on-chip light source. One of the approaches to achieve this is by epitaxially growing quantum dot laser stack on silicon substrate. Over the past few years, we, together with our colleagues around the world, have made significant improvements in the material quality of the epitaxially grown quantum dot lasers. Yet, little efforts have been taken in integrating the grown quantum dot material with passive waveguide structures.In this thesis, we first dive into the gain characteristics of the quantum dot laser material. A novel measurement technique is adopted to allow studying the unique properties of quantum dot active region under the influence of different growth techniques. Such knowledge provides insights on how to further improve the performance of quantum dot lasers. With sufficient understanding of the quantum dot material, we designed a novel device platform which enables integration of quantum dot active region with passive waveguide structure. By doing so, complex laser cavities such as DBR lasers, mode-locked lasers, and SGDBR tunable lasers are demonstrated in this platfor

Quantum dot lasers have proven to be extremely interesting in terms of nonlinear dynamics. One of the key benefits is their highly damped relaxation oscillations. In this work we take advantage of this stability in a master slave configuration. We find a novel, dual state excitable dynamic resulting in antiphase operation between two lasing states in the device. We interpret the behaviour as a non-Adler but still Type I excitability. Phase measurements bolster our interpretation., SCOPUS: cp.p, info:eu-repo/semantics/published

We monolithically fabricated vertical cavity lasers with densely packed colloidal quantum dot films and demonstrated single-mode lasing operation using nanosecond optical excitation. Due to the accurate spectral and spatial alignment of the cavity optical modes and the quantum dot gains, in addition to the high quality factors of our devices, we observed lasing from a colloidal quantum dot gain medium only 35 nm thick (6 or 7 monolayers thick) with a threshold of 20 mJ/cm2. We fabricated a laser with more numerous quantum dot layers as well, which exhibited a lower lasing threshold of 9 mJ/cm2 due to the enhanced modal gain. This work represents an important step toward fabricating monolithic colloidal quantum dot lasers for practical photonic devices.

We monolithically fabricated vertical cavity lasers with densely packed colloidal quantum dot films and demonstrated single-mode lasing operation using nanosecond optical excitation. Due to the accurate spectral and spatial alignment of the cavity optical modes and the quantum dot gains, in addition to the high quality factors of our devices, we observed lasing from a colloidal quantum dot gain medium only 35 nm thick (6 or 7 monolayers thick) with a threshold of 20 mJ/cm2. We fabricated a laser with more numerous quantum dot layers as well, which exhibited a lower lasing threshold of 9 mJ/cm2 due to the enhanced modal gain. This work represents an important step toward fabricating monolithic colloidal quantum dot lasers for practical photonic devices.

We monolithically fabricated vertical cavity lasers with densely packed colloidal quantum dot films and demonstrated single-mode lasing operation using nanosecond optical excitation. Due to the accurate spectral and spatial alignment of the cavity optical modes and the quantum dot gains, in addition to the high quality factors of our devices, we observed lasing from a colloidal quantum dot gain medium only 35 nm thick (6 or 7 monolayers thick) with a threshold of 20 mJ/cm2. We fabricated a laser with more numerous quantum dot layers as well, which exhibited a lower lasing threshold of 9 mJ/cm2 due to the enhanced modal gain. This work represents an important step toward fabricating monolithic colloidal quantum dot lasers for practical photonic devices.

This investigation examines the durability of the Quantum Dot Mode-Locked Laser (QDMLL) for use in extreme environments where ionizing radiation is a threat. These QDMLLs are fabricated using dots-in-a-well (DWELL) epitaxial structures, which utilize the unique properties of 2D and 3D quantum structures to achieve low-threshold current density in an exceptionally durable gain medium. The research at the University of New Mexico summarized in this report details the radiation hardness of the mode-locking characteristics of the lasers themselves. We show that the devices tested continue to perform well even after being dosed with sufficient ionizing radiation to simulate a long mission at geostationary orbit altitudes., The original document contains color images.

SCOPUS: ch.b, info:eu-repo/semantics/published

SCOPUS: ch.b, info:eu-repo/semantics/published

A microscopic theory is used to study the dynamical properties of semiconductor quantum dot based nanocavity laser systems. The carrier kinetics and photon populations are determined using a fully quantum mechanical treatment of the light‐matter coupling. In this work, we investigate the dependency of the modulation response in such devices on the number of emitters coupled to the cavity mode. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)