[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Collective Laser Emission in Coupled Hybrid InP-on-SOI Nanocavities

摘要： Coupled optical micro/nanocavities have raised large attention over the last decades as their use has triggered breakthroughs in photonics such as the exploitation of electromagnetically induced transparency (EIT) effect for delaying or storing light [1]. More recently, research was initiated on the coupling between micro/nano cavities including an active medium, in order to develop optical memories [2] or to study more fundamental physical effects such as spontaneous mirror-symmetry breaking [3]. This work is focused on coupled nanolasers made of photonic crystals onto a silicon optical platform. The development of ultra-compact and power efficient laser sources on this type of platform is crucial to enable the deployment of on chip optical interconnects. We already demonstrated an electrically powered single nanolaser integrated on SOI (Silicon-On-Insulator) [4]. To go beyond, we present here the study of the collective laser emission arising from the coupling of two identical photonic crystal nanobeam cavities made of InP materials through a SOI wire. The coupled system is fabricated by bonding a III-V semiconductor heterostructure onto a SOI optical waveguide circuitry. The InP-based slab is then patterned using electron beam lithography followed by inductively coupled plasma etching [Fig. 1]. We show that this hybrid platform is very versatile to change at will, both the coupling strength and phase. Indeed, the coupling strength can easily be tuned by changing the SOI wire width. Regarding the coupling phase, it is controlled by varying the relative distance of the 2 cavities made atop the SOI waveguides [Fig. 2]. We demonstrate that collective laser emission is obtained at 1.55μm at room temperature by CW optically pumping at 1180nm. It is obtained when the coupling phase is near a multiple of π. Compared to stand alone structures, this coupled configuration results in a drastic reduction of the laser threshold and an improvement of the slope efficiency [Fig. 3], due to the control of the coupling phase to reduce the losses in the coupled system. This is an unprecedented manner to achieve simultaneously low threshold and high coupling efficiency to the SOI waveguide circuitry. In the same time, this configuration allows to investigate interesting fundamental physical effects, such as superradiance, lasing effect without inversion of population [5], but also to study the existence of exceptional points [6] and dark modes [7] in this kind of coupled system.