Until recently, a full development of an AlGaAs photonic platform has been hindered by the difficulty of fabricating monolithic shallow waveguides and cavities as in the silicon-on-insulator (SOI) system. This is due on one hand to the technological burden of hybridizing Aluminium Gallium Arsenide (AlGaAs) on SOI via wafer bonding, and on the other hand to the shortcomings of the selective oxidation of AlGaAs epitaxial layers. While the use of Aluminium Oxide (AlOx) layers thinner than 100 nm is used in VCSEL technology and enabled our group to demonstrate an optical parametric oscillator in an AlGaAs waveguide [1], the fabrication of high-quality micron-thick AlOx optical substrates is critical because the selective oxidation of AlGaAs optical substrates induces a strong contraction of the oxide and important optical losses in integrated photonic devices due to defects at the interface between AlOx and the adjacent crystal.
This Master/PhD proposal stems directly from the technological breakthrough performed by our team in the last year [2], resulting in the fabrication of AlGaAs layers on top of a good-quality optical substrate of AlOx. With this know-how, we have demonstrated the first AlGaAs monolithic optical nanoantenna, and the smallest controllable second harmonic generation (SHG) source to date [3]. This result adds to the present interest in non-plasmonic nanophotonics, which is due to its negligible dissipative losses and strong multipolar magnetic resonances in the visible and near infrared. The SHG efficiency of MPQ nanoantennas improves the record of metallic nanoantennas by five orders of magnitude, under the same excitation conditions.
Here we will exploit these recent results at both the nano- and the micro-scale, with the design, fabrication and experimental demonstration of : 1) semiconductor metasurfaces based on AlGaAs-on- insulator oligomers, with applications to nonlinear holograms and surface-enhanced Raman scattering (SERS) ; 2) optical frequency comb generation in high-Q microrings, via χ(2) nonlinear interactions.
The candidate will carry out challenging and exciting forefront research in the DON nonlinear optics lab and in the clean room of MPQ, taking benefit from top-level international collaborations with the King’s College in London, the Australian National University in Canberra and the University of Brescia in Italy, in the framework of the EU-Asia-Pacific “Nanophi” Erasmus-Mundus Consortium. At the national level, strong interactions are under way with the LPN (now C2N) in Marcoussis and the Thales-Nokia-CEA III-V Lab in Palaiseau, while within Sorbonne Paris Cité we have crucial scientific interactions with high-level teams on transmission electron microscopy (MPQ), SERS (ITODYS) and cathode-luminescence (LSPM).
[1] M. Savanier et al., Appl. Phys. Lett. 103, 261105 (2013).
[2] G. Leo, O. Stepanenko, A. Lemaître, brevet FR1670043 (16/2/2016).
[3] V. Gili et al., Optics Express 24, 15965 (2016).