Suspended GaN-based nanostructure for integrated optics

We show the fabrication and characterization of a suspended GaN-based nanostructure in the visible wavelength region that combines InGaN/GaN multiple quantum wells (MQWs) active layer with rib waveguides and then creates multiple separate beamlets. It is implemented on a GaN-on-silicon platform, where silicon substrate is removed and suspended epitaxial films are thinned by back wafer etching technique. When the InGaN/GaN MQWs active layer is optically excited, part of the emitted light is confined inside epitaxial films and acts the light source. The lateral propagation direction is controlled by the rib waveguide, and the light intensity and the propagation mode can be tuned by changing the rib waveguide structure. Experimental and simulated results indicate the proposed suspended GaN-based structure is promising for the integration of emitting device with planar optical circuit in the visible wavelength region.