Directional light output from photonic-wire microcavity semiconductor lasers

We have obtained directional light output from a recently realized InGaAsP photonic-wire microcavity ring lasers. The output was achieved by fabricating a 0.45-mu m-wide U-shape waveguide next to a 10-mu m diameter microcavity ring laser. The laser has a threshold pump power of around 124 mu W when optically pumped at 514 nm. It is comparable to the former structure without output coupling. The output coupling efficiency can be controlled carefully by choosing the spacing between the laser cavity and the waveguide.