Monolithic integration of a quantum-well laser and an optical amplifier using an asymmetric twin-waveguide structure

We demonstrate the monolithic integration of a 1.55 μm wavelength InGaAsP-InP multiple-quantum-well (MQW) laser and a traveling-wave optical amplifier using an asymmetric, vertical twin-waveguide structure. The laser and amplifier share the same strained InGaAsP MQW active layer grown by gas-source molecular beam epitaxy, while the underlying passive waveguide layer is used for on-chip optical interconnections between the active devices. The asymmetric twin-waveguide structure uses the difference in modal gains to discriminate between the even and odd modes.