We have established the basis for Template-Assisted-Selective-Epitaxy for photonic devices. TWe started with the binary material GaAs as this is the easiest from a growth perspective. Using this we achieved room temperature lasing in monolithically integrated micro-discs using two different integration approaches. Direct cavity growth (S. Wirths et al. ACS Nano, 12(3), 2018) and via a two-step virtual substrate approach (B. Mayer et al. IEEE Photonic Tech. Lett 2019). We moved on to InP and compared the performance of monolithic InP microdisk lasers to identical devices fabricated by state-of-the-art direct wafer bonding and etching, and found the performance to be comparable which is evidence of a high crystal quality (S. Mauthe et al. IEEE J. Select. Top. Quantum Electron. 25 (6) 2019).
We then moved to ternary compound, and demonstrated InGaAs micro-cavity lasers using the virtual substrate approach (S. Mauthe et al. , SPIE Europe, 2018). However, the two-step growth mode means that it is very hard to control the composition for ternary compounds. Hence those InGaAs devices only lase up to about 150K. In a more recent work we grew InGaAs micro-disk lasers directly in a one-step growth and achieved room temperature lasing (P. Tiwari et al. CLEO Europe 2021).
We developed a new type of hybrid III-V/Si 1D beam Photonic crystal resonator where individual Si rods are selectively replaced by III-V gain material to position the III-V material only at the center of the resonant cavity (S. Mauthe et al. Nano Letters 20 (12), 2020). A similar approach was used to demonstrate scaled monolithic InGaAs detectors on Si (S. Mauthe et al. Nature Communications 11 (1), 2020), and in a recent work this was extended to larger structures containing and InGaAs/InP heterostructure for improved carrier confinement and waveguide coupling to Si waveguides (P. Wen et al. accepted for publication - available as preprint: arXiv:2106.00620). In this work we also demonstrated LED operation even if we did not yet achieve electrically actuated lasing.
We also worked on the use of metals for the hybrid photonic-plasmonic cavities. We evaluated several in-house deposition methods for both Ag, Au as well as metal nitrides. We investigated the scaling potential of InP microdisk lasers of different geometries with and without a Au metal cladding and found that whereas the use of a metal cladding increases the threshold the devices can be scaled to smaller dimensions (P. Tiwari, Optics Express 29 (3), 2021). We carried out a thorough analysis on the thermal properties and found this to be dramatically impacted by the presence of the metal cavities (P. Wen et al. manuscript in preparation). We further investigated the use of Au nanoantennae coupled to InP micro-disk lasers and found them to have a strong impact on the emission properties in terms of side-mode suppression and temperature stability (pre-print available on: arXiv:2110.11204 article under review).
