Strip-loaded horizontal slot waveguide for routing microdisk laser emission

A strip-loaded horizontal slot waveguide is used for routing the emission of a microdisk laser. The active region of the laser contains InAs/InGaAs/GaAs quantum dots operating in CW mode under optical pumping. Although the quantum dots emit in abroad range, the laser emission is single mode with lambda = 1290 nm. Atomic layer deposition is used for the fabrication of the TiO2/SiO2/TiO2 slot waveguide covering the 10-mu m-diameter disk. The horizontal slot waveguide covers the microdisk and traps the emission in the fundamental TM mode of the three-stack layer. Once light is localized inside this planar waveguide, a loading strip creates an effective index difference, which is sufficient to confine the mode laterally and leads to the guiding of the lasing emission. An analytical model for the five-layer horizontal planar slot waveguide was developed in order to optimize the slot waveguide according to the operation wavelength of the microlaser and the different materials involved. Scanning near-field optical microscopy is used to observe the propagation of light within the waveguide and confirm the mode coupling into it and therefore the guiding along the loading strip. (C) 2020 Optical Society of America