## 6 Conclusions  
In this paper, heterogeneously integrated AlGaInAs-based multiple quantum well laser sources on silicon by InP-seed-bonding and regrowth have been presented. The thermal strain assessment from curvature measurement revealed a compressive strain value of 400 ppm at growth temperature. The latter is due to the mismatch of coefficient of thermal expansion between InP and Si. In spite of this strain, a 3 \(\upmu\)m-thick laser structure grown on an InP seed-bonded Si substrate (InPoSi) has been demonstrated, providing similar performance to the ones obtained from the same structure grown on a native InP wafer used as a reference. Broad-area lasers obtained from these structures showed a threshold current of 0.4 kA/cm\({}^{2}\) under pulse regime at 20 \({}^{\circ}\)C and a laser efficiency of 0.092 W/A. Therefore, there is no penalty induced for a 3 \(\upmu\)m-thick structure grown on InPSi in spite of the thermal strain. In addition, a specific SAG process developed on InP seed-bonded silicon wafers was presented. Selectively regrown multiple quantum well active regions successfully cover a PL range of 160 nm. Using this growth technique, a 5-channel laser array was selectively grown and fabricated. The latter covers a 155 nm-wide spectral range from 1515 nm to 1670 nm. High power operation under continuous wave operation was demonstrated with a maximum of 20 mW for a 200 mA driving current for a 500 \(\upmu\)m-long bar. High  
Figure 14: 3D Schematic view of the III-V on SOI DBR laser including a III-V gain region coupled to a Si waveguide, Bragg mirrors and vertical couplers. Figure 15: (**a**) Simulation of the reflection of the grating mirrors against wavelength with the high reflective mirror in blue and the low reflective mirror in red; (**b**) Waveguide-coupled output power against injected current measured under CW operation @20 \({}^{\circ}\)C; (**c**) Spectra measured @20 \({}^{\circ}\)C for 80 mA and 120 mA injected currents. thermal stability was shown up to 70 \({}^{\circ}\)C for the lasers emitting from 1515 nm to 1610 nm. Improvements could be done to homogenize laser performance over the full spectral band. The design of the active region could be further optimized to cover the broad range achieved by SAG. Therefore, SAG technique has proved its potential for high-density high-performance integration of PICs. Its potential could be further extended for the integration of lasers, modulators and SOAs by tuning their bandgap at will to match the optimum performance of each individual device [39; 45]. Last but not least, AlGaInAs MQW-based lasers were successfully grown on heterogeneous InP-SOI wafer. CW lasing operation up to 40 \({}^{\circ}\)C has been demonstrated for III-V-on-SOI FP lasers containing hybrid optical modes where 80% of the mode is confined in the Si waveguide. In addition, lasing operation was also demonstrated for a laser grown on InP-SOI coupled to Si-photonic DBR cavities under CW operation at 20 \({}^{\circ}\)C. In our case, the use of buried heterostructures such as Buried Ridge Structure (BRS) or even Semi-Insulating Heterostructure (SIBH) could be a path to improve heat dissipation through InP lateral cladding layers [26]. Altogether, this demonstration shows that this integration scheme holds a promising perspective by combining the advanced regrowth technologies developed in the InP platform combined with the benefits of Si photonics platform. Extensive research and development are still needed to explore multiple regrowth on InP-SOI wafers to fully explore the potential of this platform. Among all III-V/Si integration schemes, the holy grail is to take full benefits of the Si platform in a 200 or 300 mm fabrication line. In this context, applying the regrowth technique on thin InP membrane coupons bonded on large Si wafers using die-bonding approach is appealing [46; 47]. In addition, investigating options to reuse the III-V substrate is another key ongoing subject [48].