Proposal of Photonic Analog-to-digital Conversion Using Weighted Multiwavelength Pulses and Balanced Photodetector

A novel photonic analog-to-digital conversion (ADC) scheme using weighted multi-wavelength pulses and balanced photodetector (BPD) is proposed. The presented system contains a multi-wavelength pulsed source, a dual-output Mach-Zehnder modulator (DOMZM), a BPD and a comparator. The weighted multi-wavelength pulses are dispersed in time via dispersive fibers, and each pulse with specific wavelength corresponds to one bit of digital output. With simple and compact structure, this approach can reduce the system complexity and avoid the synchronization difficulty among signals applied to multiple modulators. Besides, it can realize ADCs with higher resolution by simply increasing the number of wavelength and properly designing the power ratio. Theoretical analysis is presented, which facilitates the design of photonic ADCs. For a better explanation, a photonic ADC with 6 wavelengths is exemplified. Numerical simulation is implemented to verify the feasibility of the proposed approach.