Lasing from semiconductor microring on the end of an optical fiber

Isolated InGaAsP microrings with an outer diameter of 5.8 μm, a width of 1 μm, and a thickness of 0.41 μm were fabricated by epitaxial separation. Individual devices were bonded to multimode optical fiber using Van der Waals forces and optically pumped through the fiber. Lasing around 1505 nm was measured under pulsed and cw pumping at room temperature. The threshold pump power for pulsed operation was estimated to be 38 and 80 μW for cw operation. Multiple radial and azimuthal modes were present due to strong, three-dimensional confinement. Under strong pulsed pumping thermal effects caused the emission wavelength to chirp.