## 1 Introduction
However, \(\upmu\)TP not only requires cost-effective bonding alignments but is also limited to the III-V fabrication process line. More recently, an advanced heterogeneous scheme based on wafer-seed-bonding and epitaxial regrowth has emerged. The latter allows us to combine the advantages of the monolithic III-V/Si approach without the two major dislocation origins (APDs, lattice mismatch) thanks to the bonding process. Moreover, the possibility to use a thin bonding layer enables efficient light-coupling and therefore complex III-V/Si PICs. This approach was first pioneered by NTT group, whose approach is based on a MQW active regionintegrated on Si wafer by bonding followed by lateral InP regrowth to form an horizontal p-i-n junction [20]. Regrowth of MQW-based active region was also successfully done to achieve band-gap tuning by Selective Area Growth technique (SAG) [21]. Altogether, this approach enabled impressive device performance [22]. However, it has been reported that crystal degradation is observed for a 350 nm-thick structure regrown on bonded template due to the thermal strain induced by the difference of CTE between III-V and Si materials [20]. Therefore, it requires an unconventional process based on an extra growth step to form the thin lateral p-i-n junction as compared to the traditional InP monolithic approach usually based on a single growth step to form the \(\upmu\)m-thick vertical p-i-n junction. Altogether, this approach cannot be easily applied for most commercial epitaxial providers and consequently its scalability is jeopardized. In the meantime, other groups have developed an approach based on InP-seed-bonding and regrowth of \(\upmu\)m-thick vertical p-i-n junctions [23; 24; 25]. The ambition is to create a generic integration scheme combining the best offered by the III-V and the Si photonics platforms. The regrowth capability gives access to the large epitaxial toolkit available in the conventional InP monolithic platform, where several epitaxial steps are often implemented [26; 27; 28]. For example, buried lasers, as compared to ridge waveguide lasers, are highly beneficial to reduce power consumption and enhance thermal stability [29; 30]. In this context, HP group have reported pulsed and CW laser demonstrations up to 20 \({}^{\circ}\)C based on the regrowth of a 2.5 \(\upmu\)m-thick GaInAsP-MQW laser coupled to a Si-waveguide [31]. Their approach involves InP-Si bonding using Vertical Outgassing Channels (VOCs) buried under the III-V stack to absorb the generated gas produced at the bonding interface [10]. Then, these VOCs have to be opened up by etching the III-V stack in order to be compatible with MOVPE annealing temperature [32], which induces alignment constraints and more complexity to the fabrication process. In this context, we developed a novel integration scheme based on InP-seed-bonding and regrowth using an oxide layer at the bonding interface thick enough to act as a hydrogen reservoir [33]. Therefore, our platform involves \(\upmu\)m-regrowth on a planar InP-seed layer bonded on a SOI wafer. In this paper, we first introduce our fabrication process to integrate AlGaInAs-based lasers on SOI wafer by InP-seed-bonding and regrowth (Section 2). Then, Section 3 provides the development of a 3 \(\upmu\)m-thick AlGaInAs-based laser structure grown on InP-SiO\({}_{2}\)/Si (InPoSi) wafer compared to the same structure grown on InP wafer as a reference. After assessing the thermal strain induced in the structure grown on InPSi by in situ curvature measurements, morphological characterizations as well as broad-area lasers static performance are presented. Section 4 presents the implementation of the SAG technique in our platform. A 155 nm-wide AlGaInAs-MQW based laser array covering the C+L band fabricated from a single-step SAG process on InPSi is described. Finally, Section 5 describes the first demonstration of an AlGaInAs regrown laser efficiently coupled to Si-photonics cavities.