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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 platform. The same laser stack can be easily grown on the substrate of a silicon photonic chip to allow light coupling from the III-V laser cavity to the silicon waveguide.

We directly compare the performance of 1.55 $\mu \text{m}$ Fabry-Perot lasers using quantum well (QW) and quantum dash gain regions. Other than the gain medium the designs were identical, grown in the same growth system, and processed at the same time. The static laser performance (light-current and spectral) were similar for both gain materials but the intensity and phase noise characteristics of the dash based lasers were significantly better. This was attributed to the self mode-locking of the dash lasers that was not observed for the QW lasers. This reduction in noise allowed individual lasing lines from the Fabry-Perot dash lasers to be used for data transmission using high order modulation schemes, with quadrature phase-shift keying (QPSK) demonstrated at a symbol rate of 32GBaud. This performance could not be achieved using the equivalent QW based laser.

Semiconductor nanostructures with low dimensionality like quantum dots and quantum dashes are one of the best attractive and heuristic solutions for achieving high performance photonic devices. When one or more spatial dimensions of the nanocrystal approach the de Broglie wavelength, nanoscale size effects create a spatial quantization of carriers leading to a complete discretization of energy levels along with additional quantum phenomena like entangled-photon generation or squeezed states of light among others. This article reviews our recent findings and prospects on nanostructure based light emitters where active region is made with quantum-dot and quantum-dash nanostructures. Many applications ranging from silicon-based integrated technologies to quantum information systems rely on the utilization of such laser sources. Here, we link the material and fundamental properties with the device physics. For this purpose, spectral linewidth, polarization anisotropy, optical nonlinearities as well as microwave, dynamic and nonlinear properties are closely examined. The paper focuses on photonic devices grown on native substrates (InP and GaAs) as well as those heterogeneously and epitaxially grown on silicon substrate. This research pipelines the most exciting recent innovation developed around light emitters using nanostructures as gain media and highlights the importance of nanotechnologies on industry and society especially for shaping the future information and communication society., Quantum dot are one of the best practical examples of nanotechnologies. Owing to the discrete energy levels, quantum dot lasers output unique features like thermal stability, feedback insensitivity and spectral purity.

Optical interconnects enabled by silicon microring-based transceivers offer great potential for short-reach data communication in future high-performance computing systems. However, microring resonators are prone to process variations that harm both the energy efficiency and the yield of the fabricated transceivers. Especially in the application scenario where a batch of transceivers are fabricated for assembling multiple optical networks, how the transceivers are mixed and matched can directly impact the average energy efficiency and the yield of the networks assembled. In this study, we propose transceiver grouping for assembling communication networks from a pool of fabricated transceivers, aiming to optimize the network energy efficiency and the yield. We evaluated our grouping algorithms by wafer-scale measurement data of microring-based transceivers, as well as synthetic data generated based on an experimentally validated variation model. Our experimental results demonstrate that optimized grouping achieves significant improvement in the network energy efficiency and the yield across a wide range of network configurations, compared to a baseline strategy that randomly groups the transceivers.

This paper investigates the impact of dislocation density and active layer structure on the degradation mechanisms of 1.3 $\mu \text{m}$ InAs Quantum Dot (QD) lasers for silicon photonics. We analyzed the optical behavior of two sets of samples, having different dislocation densities and different number of quantum dot layers in the active region. The samples were subjected to a short-term step-stress experiment and to long-term constant current operation in order to investigate the dominant degradation processes. The results indicate that: (i) the temperature stability is much higher in the devices grown on native substrate, thanks to the lower defect density; (ii) the roll-off current is considerably higher for the devices with higher number of layers, due to the lower density of carriers in the QDs; (iii) in nominal ground-state operating regime, the degradation rate is limited by the density of dislocations, that may serve as preferential paths for the diffusion of non-radiative recombination centers; (iv) at extreme injection levels and operating temperatures, the devices exhibit a blue shift of the spectral emission; possible explanations for this process are discussed in the paper.

In this work, we present an approach to modelling III-V lasers on silicon based on a travelling-wave rate equation model with sub-micrometer resolution. By allowing spatially resolved inclusion of individual dislocations along the laser cavity, our simulation results offer new insights into the physical mechanisms behind the characteristics of 980 nm In(Ga)As/GaAs quantum well (QW) and 1.3 mu quantum dot (QD) lasers grown on silicon. We identify two effects with particular importance for practical applications from studying the reduction of the local gain in carrier-depleted regions around dislocation locations and the resulting impact on threshold current increase and slope efficiency at high dislocation densities. First, a large minority carrier diffusion length is a key parameter inhibiting laser operation by enabling carrier migration into dislocations over larger areas, and secondly, increased gain in dislocation-free regions compensating for gain dips around dislocations may contribute to gain compression effects observed in directly modulated silicon-based QD lasers. We believe that this work is an important contribution in creating a better understanding of the processes limiting the capabilities of III-V lasers on silicon in order to explore suitable materials and designs for monolithic light sources for silicon photonics.

In this study, the research on the nonlinear dynamics of semiconductor quantum dot laser with two time-delayed optical feedbacks is numerically investigated. Results show that the nonlinear dynamics behaviors of the laser are very sensitive to the rich system parameters in which both feedback strength and bias current are easily controlled to significantly influence the nonlinear dynamics including the periodic state and chaotic state. By judiciously adjusting the bias current of the laser or the feedback strength in the external cavity, period one, period doubling, quasi-period, and chaos are achieved. The feedback level-related bifurcation diagrams are analyzed in detail while fixing another feedback level at a constant or varying the bias current. In addition, the translation variables of the 0–1 test method that are clearly bounded for regular behavior and exhibit the Brownian motion for irregular phenomenon are adopted to further evaluate the periodic state and the chaotic state. These results can give insight into the quantum dot laser–based applications in various optical technologies.

Optical connectivity, which has been widely deployed in today's datacenters and high-performance computing (HPC) systems, is a disruptive technological revolution to the IT industry in the new Millennium. In our journey to debut an Exascale supercomputer, a completely new computing concept, called memory-driven computing, was innovated recently. This new computing architecture brings challenges and opportunities for novel optical interconnect solutions. Here, we first discuss our strategy to develop appropriate optical link solutions for different data traffic scenarios in memory-driven HPCs. Then, we present detailed review on recent work to demonstrate fully photonics-electronics-integrated single- and multi-wavelength directly modulated laser (DML) transmitters on silicon for the first time. Compact heterogeneous microring lasers and laser arrays were fabricated as photonic engines to work with a customized complementary metal-oxide semiconductor (CMOS) driver circuit. Microring lasers based on conventional quantum well and new quantum dot lasing medium were compared in the experiment. Thermal shunt and MOS capacitor structures were integrated into the lasers for effective thermal management and ultra low-energy tuning. It enables a controllable dense wavelength division multiplexing (DWDM) link architecture in an HPC environment. An equivalent microring laser circuit model was constructed to allow photonics-electronics co-simulation. Equalization functionality in the CMOS driver circuit proved to be critical to achieve up to 14 Gb/s direct modulation with 6 dB extinction ratio. Finally, the on-going and future work is discussed towards more robust, higher speed, and more energy efficient DML transmitters.

Photonic integrated circuits (PICs) have enabled numerous high performance, energy efficient, and compact technologies for optical communications, sensing, and metrology. One of the biggest challenges in scaling PICs comes from the parasitic reflections that feed light back into the laser source. These reflections increase noise and may cause laser destabilization. To avoid parasitic reflections, expensive and bulky optical isolators have been placed between the laser and the rest of the PIC leading to large increases in device footprint for on-chip integration schemes and significant increases in packaging complexity and cost for lasers co-packaged with passive PICs. This review article reports new findings on epitaxial quantum dot lasers on silicon and studies both theoretically and experimentally the connection between the material properties and the ultra-low reflection sensitivity that is achieved. Our results show that such quantum dot lasers on silicon exhibit much lower linewidth enhancement factors than any quantum well lasers. Together with the large damping factor, we show that the quantum dot gain medium is fundamentally dependent on dot uniformity, but through careful optimization, even epitaxial lasers on silicon can operate without an optical isolator, which is of paramount importance for the future high-speed silicon photonic systems.

This work investigates the degradation processes affecting the long-term reliability of 1.3 μm InAs quantum-dot lasers epitaxially grown on silicon. By submitting laser samples to constant-current stress, we were able to identify the physical mechanisms responsible for the optical degradation. More specifically, the samples (i) exhibited a gradual increase in threshold current, well correlated with (ii) a decrease in sub-threshold emission, and (iii) a decrease in slope efficiency. These variations were found to be compatible with a diffusion process involving the propagation of defects toward the active region of the device and the subsequent decrease in injection efficiency. This hypothesis was also supported by the increase in the defect-related current conduction components exhibited by the electrical characteristics, and highlights the role of defects in the gradual degradation of InAs quantum dot laser diodes. Electroluminescence measurements were used to provide further insight in the degradation process.

Dynamics of a multimode quantum dot laser with polarization-rotated optical feedback is investigated in a wide range of bias current. The results reveal that the laser is more sensitive to optical feedback when the polarization of feedback beam is rotated a large angle from the original polarization, which is different from the results in DFB lasers. Anticorrelated fluctuations between orthogonal polarizations are observed in a certain range of selected polarizations. Accordingly, dynamics in the total power can be weaker than that in a selected polarization. The anticorrelated polarization dynamics may be related to different polarizations of longitudinal modes.

This paper reviews optical injection locking (OIL) of semiconductor lasers and its application in optical communications and signal processing. Despite complex OIL dynamics, we attempt to explain the operational principle and main features of the OIL in an intuitive way, aiming at a wide understanding of the OIL phenomenon and its associated techniques in the optic and photonic communities. We review and compare different control techniques that enable robust OIL in practical systems. The applications are reviewed with a focus on new developments in the past decade, under the categories of ‘High Speed Directly Modulated Lasers’ and ‘Optical Carrier Recovery’. Finally, we draw our vision for future research directions.

$p$ -type modulation doping of the quantum dot active region is known to improve high temperature and dynamic performance of quantum dot lasers. These improvements are critical to realizing commercially relevant quantum dot devices on silicon and are shown to enable continuous wave operation over 100°C, nearly complete insensitivity to optical feedback, and orders of magnitude improvement in device reliability relative to unintentionally doped active regions. Also described is a spectrally resolved analysis of the effect of p-modulation doping on the optical gain revealing anomalous behavior that explains the high characteristic temperatures commonly observed in literature for similar devices on native substrate.

Dual-state emission is a common and important phenomenon which takes place in semiconductor Quantum Dot Lasers at different temperature and operating conditions usually investigated from microscopic carrier interaction modeling or even rate-equations based approaches. In this study, we revisit the topic, but the investigation is here performed from a system identification perspective; we built black-box models based on artificial neural networks approach, using the Multilayer Perceptron, the Extreme Learning Machine and a hybrid Echo State Network - Extreme Learning Machine. As a case study, we focused on switch-on transient and its prediction. The study revealed the model was able to separate and to predict, from the solely total power, without using any QDL design parameters, the optical power around the ground state and first excited state lasing lines of InAs/InGaAs quantum dot laser. The error performance was low as a RMSE of 2.81 μW and MAPE of 0.50% with processing time (training and testing time) of 15.27 s, enabling the alternative model to be used in optical filtering instrumentation as low-resolution and low-cost filters for applications in which it is not economically viable to use a spectrum analyzer, which can be replaced by a simple optical power meter.

Quantum dot (QD) laser as a light source for silicon optical integration has attracted great research attention because of the strategic vision of optical interconnection. In this paper, the communication band InAs QD ridge waveguide lasers were fabricated on GaAs-on-insulator (GaAsOI) substrate by combining ion-slicing technique and molecular beam epitaxy (MBE) growth. On the foundation of optimizing surface treatment processes, the InAs/In0.13Ga0.87As/GaAs dot-in-well (DWELL) lasers monolithically grown on a GaAsOI substrate were realized under pulsed operation at 20 °C. The static device measurements reveal comparable performance in terms of threshold current density, slope efficiency and output power between the QD lasers on GaAsOI and GaAs substrates. This work shows great potential to fabricate highly integrated light source on Si for photonic integrated circuits.

Funding: This paper incorporates results obtained from the project, JPNP20017, commissioned by 474 the New Energy and Industrial Technology Development Organization (NEDO) in Japan. Here, we report on the design and performance of a silicon photonic micro-transceiver required to operate in 5G and 6G environments at high ambient temperatures above 105 °C. The four-channel “IOCore” micro-transceiver incorporates a 1310 nm quantum dot laser system and operates at a data rate of 25 Gbps and higher. The 5 × 5 mm micro-transceiver chip benefits from a multimode coupling interface for low-cost assembly and robust connectivity at high temperatures as well as an optical redundancy scheme, which increases reliability by over an order of magnitude. Publisher PDF

A semi-empirical model is compared with measurements to establish limiting factors in the performance of p-modulation doped InAs quantum dot (QD) lasers. Fitted absorption spectra allow identification of supposed factors and comparison of multiple samples isolates their origin, providing insights for future laser design.

III-V semiconductor lasers integrated on Si-based photonic platforms are eagerly awaited by the industry for mass-scale applications, from interconnect to on-chip sensing. The current understanding is that only quantum dot lasers can reasonably operate at the high dislocation densities generated by the III-V-on-Si heteroepitaxy, which induces high non-radiative carrier recombination rates. Here we propose a strategy based on a type-II band alignment to fabricate quantum well lasers highly tolerant to dislocations. A mid-IR GaInSb/InAs interband cascade laser grown on Si exhibits performances similar to those of its counterpart grown on the native GaSb substrate, in spite of a dislocation density in the 10 8 c m − 2 range. Over 3800 h of continuous-wave operation data have been collected, giving an extrapolated mean time to failure exceeding 312,000 h. This validates the proposed strategy and opens the way to new integrated laser development.

We review results on the optical injection of dual state InAs quantum dot-based semiconductor lasers. The two states in question are the so-called ground state and first excited state of the laser. This ability to lase from two different energy states is unique amongst semiconductor lasers and in combination with the high, intrinsic relaxation oscillation damping of the material and the novel, inherent cascade like carrier relaxation process, endows optically injected dual state quantum dot lasers with many unique dynamical properties. Particular attention is paid to fast state switching, antiphase excitability, novel information processing techniques and optothermally induced neuronal phenomena. We compare and contrast some of the physical properties of the system with other optically injected two state devices such as vertical cavity surface emitting lasers and ring lasers. Finally, we offer an outlook on the use of quantum dot material in photonic integrated circuits.

We propose a multilayer silicon nitride (SiN) -on-silicon photonic integrated circuit (PIC) platform with a monolithic laser at the C-band. A tapered edge coupler and a meta-structure-based interlayer directional coupler in the platform were designed to realize low-loss broadband laser-to-chip 3D coupling with small footprint. The coupling length of the interlayer directional coupler and the gap between different SiN layers were optimized as 12.7 µm and 1.4 µm. We measured the 1-dB-drop optical operation bandwidth of greater than 76 nm and the coupling loss of 6.1 ± 0.1 dB at 1550 nm for the interlayer directional coupler. The hybrid integration was demonstrated as a proof of concept for monolithic integration of light sources. The butt-coupling loss of 3.7 ± 0.1 dB between an on-chip DFB laser and a SiN edge coupler at 1549.48 nm was achieved. This approach opens the possibility of employing monolithic laser in the silicon photonics platform.

We demonstrate the superior emission properties of a red-emitting self-assembled quantum dot microsphere laser made from a blend of green and red bandgap CdS x Se 1-x / ZnS quantum dots. The addition of the higher bandgap material reduces self-absorption and improves the Q-factor.

International audience; How far can we go in shaping the luminescence of quantum emitters? It is well known that by using cavities or nano-antennas, one can beam their luminescence into well-controlled directions of space. Here, we push this control to a level of complexity usually achieved with laser radiation: we make an assembly of colloidal quantum dots spontaneously emit vector vortex beams, which are swirls of light combining a non-zero angular momentum and an inhomogeneous field structure. The key ingredient to obtain this result is to increase the spatial coherence of the emitted photons. To fulfill this condition, we design and use plasmonic holograms that also impart a non-zero orbital angular momentum and a radial polarization state to the beam.

International audience

For the first time gain-switched short pulse generation with a width of 25-40 ps from excited state is demonstrated applying an external optical Gaussian beam to the excited state of InAs-InP-(113)B quantum dot laser.

Quantum cascade lasers (QCLs) facilitate compact optical frequency comb sources that operate in the mid-infrared and terahertz spectral regions, where many molecules have their fundamental absorption lines. Enhancing the optical bandwidth of these chip-sized lasers is of paramount importance to address their application in broadband high-precision spectroscopy. In this work, we provide a numerical and experimental investigation of the comb spectral width and show how it can be optimized to obtain its maximum value defined by the laser gain bandwidth. The interplay of nonoptimal values of the resonant Kerr nonlinearity and cavity dispersion can lead to significant narrowing of the comb spectrum and reveals the best approach for dispersion compensation. The implementation of high mirror losses is shown to be favorable and results in proliferation of the comb sidemodes. Ultimately, injection locking of QCLs by modulating the laser bias around the round trip frequency provides a stable external knob to control the frequency-modulated comb state and recover the maximum spectral width of the unlocked laser state.

A modified rate equation model was presented to theoretically investigate the nonlinear dynamics of solitary two-state quantum dot lasers (TSQDLs) under optical feedback. The simulated results showed that, for a TSQDL biased at a relatively high current, the ground-state (GS) and excited-state (ES) lasing of the TSQDL can be stimulated simultaneously. After introducing optical feedback, both GS lasing and ES lasing can exhibit rich nonlinear dynamic states including steady state (S), period one (P1), period two (P2), multi-period (MP), and chaotic (C) state under different feedback strength and phase offset, respectively, and the dynamic states for the two lasing types are always identical. Furthermore, the influences of the linewidth enhancement factor (LEF) on the nonlinear dynamical state distribution of TSQDLs in the parameter space of feedback strength and phase offset were also analyzed. For a TSQDL with a larger LEF, much more dynamical states can be observed, and the parameter regions for two lasing types operating at chaotic state are widened after introducing optical feedback.

We experimentally investigate the complex dynamics of a multi-mode quantum-dot semiconductor laser with time-delayed optical feedback. We examine a two-dimensional bifurcation diagram of the quantum-dot laser as a comprehensive dynamical map by changing the injection current and feedback strength. We found that the bifurcation diagram contains two different parameter regions of low-frequency fluctuations. The power-dropout dynamics of the low-frequency fluctuations are observed in the sub-GHz region, which is considerably faster than the conventional low-frequency fluctuations in the MHz region. Comparing the dynamics of quantum-dot laser with those of single- and multi-mode quantum-well semiconductor lasers reveals that the fast low-frequency fluctuation dynamics are unique characteristics of quantum-dot lasers with time-delayed optical feedback.

Spin-optoelectronics is a rapidly developing field with promises to provide extra functionalities in communication and spectroscopy via ultrafast polarization modulation [1] . We are addressing the question of spin memory in InAs/GaAs quantum dots (QD) which can serve as gain structures for vertical-external cavity lasers (VECSELs), whereas most previous investigations focused on monolithic VCSELs. VECSELs offer possibilities not only for power scaling but also for additional flexibility as polarization controlling elements can be introduced into the free space sections [2] , [3] . Moreover QDs extend the wavelength coverage of GaAs based materials to the 1300 nm telecomm band with long spin lifetimes having been reported [4] . However, previous investigations concentrated on low temperatures and/or charged/doped dots and we are not aware of results on structures at strong excitation for lasing at room temperature.

Terahertz (THz) generation has a high potential for study vibrational and rotational transitions, dynamics of free carriers and phonon resonances, as well as applications for lasing, security systems, spectroscopy, biomedicine, ultrafast switching and controlling of magnetic domains, molecular alignment, particle acceleration, THz-enhanced attosecond pulse generation [1] . The challenge is to produce a compact intense THz- source, for that a development of schemes and devices providing high efficiency of frequency conversion is important. For the moment, it may reach a few percent in different schemes such as optical rectification, laser-solid interaction, two-color gas-plasma scheme, laser pumped liquid-plasma [2] . Prospective media for these aims are nanocomposites (NC) due to their large nonlinearities bringing wide set of the possibilities. Large value of permanent dipole moment (PDM) is revealed (~10 2 - 10 3 Debye) in nanostructures, in particular, semiconductor quantum dots (QDs) of ZnO, ZnS, CdSe what is comparable with values of transition dipole moments between the exciton states. As well, the additional transitions between exciton states allowed due to PDM may play a significant role in the nanoparticle response, in particular for the generation of new frequencies in the THz range.

A feedback insensitive laser is a prerequisite for a desirable laser source for silicon photonic integration, as it is not possible to include an on-chip optical isolator. This work investigates the feedback insensitivity of an InAs/GaAs quantum dot laser epitaxially grown on an Si (001) substrate by operating in a sole excited state. The experimental results show that the sole excited-state lasing InAs quantum dot lasers on Si are less sensitive to external optical feedback than both Fabry-Perot and distributed-feedback quantum-well lasers. By comparing the laser behavior under different feedback levels, sole excited-state InAs quantum dot lasers on Si exhibit at least a 28 dB stronger feedback tolerance than quantum-well lasers. This result proposes a possible route for a high feedback insensitive laser as an on-chip light source towards Si waveguide integration with the absence of an optical isolator.

Owing to the excellent properties of perovskite quantum dots (QDs), such as an easy synthesis process, high photoluminescence quantum yields, high defect tolerance, and tunable bandgap with different elements, laser actions have been widely conducted. Over the past few years, several approaches have been used for successfully creating perovskite QD lasers. In this review, we summarize the progress of perovskite QD lasers from the aspects of laser theory, characteristics and applications of QD lasers, advantages of perovskite materials for lasers, factors influencing the QD laser threshold, two‐photon pumped QD lasers, and perovskite QD laser stability. At the same time, aiming at existing problems, possible solutions and prospects are presented.

A three-fold reduction of threshold current, with a minimum threshold current density of 286 A/cm 2 , a maximum operating temperature of 80 °C, and a maximum 3 dB bandwidth of 5.8 GHz was achieved for 1.3 μm InAs quantum dot lasers on patterned, on-axis (001) Si. This was enabled by the reduced threading dislocation density (from 7×10 7 to 3×10 6 cm −2 ), and optimized probe design. The patterned Si produced antiphase domain free material in the coalesced GaAs buffer layer with reduced misfit/threading dislocation nucleation, without the use of Ge/GaP buffers or substrate miscut. Utilizing aspect ratio trapping, cyclic thermal annealing, and dislocation filter layers, high quality III-V on Si devices were grown, demonstrating the compelling advantages of this patterned Si template for a monolithic Si photonics integration platform.