We report on a novel mirror design for micro-ring semiconductor ring lasers that uses those mirrors to connect straight waveguide sections in a closed loop. The nearly parabolic mirrors are designed by ray-tracing to optimize their shape. The efficiency of the designs is verified with FDTD simulations, with a simulated coupling efficiency of 98%. We have successfully fabricated devices based on this design with an equivalent circular ring radius of 16µm. These devices operate in continuous wave at room temperature with a threshold current of only 22mA and an emission wavelength of 1.55µm.