An 8$\,\times\,$ 8 InP Monolithic Tunable Optical Router (MOTOR) Packet Forwarding Chip

In this paper, we demonstrate single-channel operation of the first InP monolithic tunable optical router (MOTOR) chip designed to function as the packet forwarding engine of an all-optical router. The device has eight-input and eight-output ports and is capable of 40-Gb/s operation per port with bit-error rates below 1E-9. MOTOR integrates eight wavelength-tunable differential Mach–Zehnder semiconductor optical amplifier (SOA) wavelength converters with preamplifiers and a passive 8$\,\times\,$ 8 arrayed-waveguide grating router. Each wavelength converter employs a widely tunable sampled-grating distributed Bragg reflector (DBR) laser for efficient wavelength switching across the C band and other functions required for 40-Gb/s wavelength conversion. Active and passive regions of the chip are defined through a robust quantum well intermixing process to optimize the gain in the wavelength converters and minimize the propagation losses in passive sections of the chip. The device is one of the most complex photonic integrated circuits (PICs) reported to date, with dimensions of 4.25 mm$\,\times\,$14.5 mm and more than 200 functional elements integrated on-chip. We demonstrate single-channel wavelength conversion and channel switching with this device using $2^{31}-1$ pseudorandom bit sequence (PRBS) data at 40 Gb/s. A power penalty as low as 4.5 dB was achieved with less than 2-W drive power per channel.