Flexible four-channel silicon-external-cavity laser with a shared ring resonator

A four-channel external-cavity laser using one shared ring resonator, which provides a frequency grid, and four slave ring resonator enables us to select the lasing frequencies of the four subchannels from the grid frequencies. A proof-of-concept experiment, performed by butt-coupling an InP semiconductor optical amplifier to a Si wire waveguide external mirror chip, demonstrated lasing of each of the four channels in two different frequency configurations.