An optical interconnect system has a transmitter and a receiver connected by a single mode fiber. An array of DML lasers in the transmitter emits multiple wavelengths which are multiplexed to the single mode fiber with an array waveguide grating (AWG) device. The receiver demultiplexes the different wavelengths by an AWG polymer waveguide fabricated in a trench on the silicon surface. The AWG demultiplexer includes a high-NA polymer waveguide which has an end reflector approximately formed at 45 degrees for reflecting light from AWG into multiple photodetectors assembled outside the trench. Optionally, a number of through-silicon-vias (TSVs) allow electrical connection access to the lasers and the driver circuit from the backside of the silicon substrate by external power sources.