Optimization of 1.3 µm InAs/GaAs quantum dot lasers epitaxially grown on silicon: taking the optical loss of metamorphic epilayers into account

Abstract

Taking the optical loss caused by the metamorphic layers into account, we have proposed an optimization strategy for 1.3 µm InAs/GaAs quantum dot (QD) laser structures directly grown on silicon. We have investigated the effects of the QD layer number, the thickness and the composition of AlGaAs cladding layers on QD laser performance. The results demonstrate, with respect to the net modal gain and the differential quantum efficiency, that the optimized QD layer number is 7 for lasers grown on silicon, which is different from the optimized number of 5 for the counterparts grown on native substrates. The optimized thickness is obtained for the cladding layers of Al 0.4 Ga 0.6 As, Al 0.6 Ga 0.4 As and Al 0.8 Ga 0.2 As. Further, the optimized QD layer number for the net modal gain is nearly independent of the material gain of active regions. More importantly, the optimization strategy provides a comprehensive method to understand the differences in design between QD laser structures on silicon and those on native substrates.

Understanding the Bandwidth Limitations in Monolithic 1.3 μm InAs/GaAs Quantum Dot Lasers on Silicon

“…In this section, we discuss how the dynamic characteristics of a QD laser grown in Si may be affected by the problems induced by the growth on a Si substrate. While the two main points of concern are arguably carrier and optical loss induced by a high dislocation density [3], [15], [39], two further, though potentially minor factors to consider are the possibility of reduced QD uniformity caused by the enhanced surface roughness of GaAs pseudo-substrates grown on Si [4], and residual tensile stress from the mismatch of the thermal expansion coefficients of GaAs and Si [19].…”

“…In addition to non-radiative recombination, the internal loss caused by dislocation-induced absorption and optical scattering can additionally compromise the performance of QD lasers on Si [39] especially with respect to the modulation speed, as optical loss effectively reduces the available gain. Whereas Wang et al have calculated waveguide loss on the order of 2.4 cm -1 to 5.5 cm -1 for the metamorphic epilayers of III/V QD lasers on Si in a similar configuration [39], Shutts et al and Jung et al have measured low internal losses of about 2.8 cm -1 [42] and 2.5 cm -1 [7], respectively, similar to what has been used in our simulations [18].…”

“…In addition to non-radiative recombination, the internal loss caused by dislocation-induced absorption and optical scattering can additionally compromise the performance of QD lasers on Si [39] especially with respect to the modulation speed, as optical loss effectively reduces the available gain. Whereas Wang et al have calculated waveguide loss on the order of 2.4 cm -1 to 5.5 cm -1 for the metamorphic epilayers of III/V QD lasers on Si in a similar configuration [39], Shutts et al and Jung et al have measured low internal losses of about 2.8 cm -1 [42] and 2.5 cm -1 [7], respectively, similar to what has been used in our simulations [18]. These values, even if possibly containing a residual dislocationinduced loss component, give clear evidence of the high crystal quality of the III/V lasers, and compare favorably with internal losses in QD lasers on native substrates [11], [32], This indicates that optical losses in monolithic QD lasers on Si are unlikely to limit their performance in a fundamental way.…”

Co-Package Technology Platform for Low-Power and Low-Cost Data Centers

“…This made the coupling between the III-V and Si waveguides inefficient for many of the QD III-V structures, so special designs were required. The second major challenge concerned the fact that previous QD demonstrations [29][30][31][32][33] always utilized thick gain stacks (epitaxial III-V thickness > 2 µm) in order to provide sufficient material gain and low losses [37]. From the L3MATRIX perspective, considering thin gain stacks that would be compatible with industrial production lines is highly desirable.…”

High-order topological states using alignment of different bandgaps in 1D superlattices

“…8,[12][13][14] This presents intriguing possibilities, as DBR or distributed feedback (DFB) mirror-based cavities are widely used in photonics applications, enabling high-quality and reliable cavities in various configurations . [15][16][17][18][19][20][21][22][23][24] Consequently, this may offer a promising avenue to seamlessly integrate topological structures with these established photonic technologies.…”