Optical Digital to Analog Converter Based on Microring Switches

We propose an N-bit optical digital to analog converter (DAC) based on an integrated optoelectronic circuit consisting of N microring switches and N 1 × 2 optical splitters, which can transform an N-bit electrical digital signal to an optical analog signal. As the proof of concept, a 2-bit optical DAC is fabricated in the silicon-on-insulator platform by CMOS-compatible process. The 2-bit electrical digital signal is firstly converted to two electrical analog signals and then employed to modulate the two microring switches through the electric-field-induced carrier injection in forward biased PIN diodes embedded in the ring waveguides. The analog optical output is detected at the output port of the circuit. A 2-bit optical DAC operating at 100 Mbps is demonstrated.