Photonic asynchronous delta‐sigma modulator system for analog‐to‐digital conversion

A novel photonic asynchronous delta‐sigma modulator (ADSM) has been investigated and demonstrated for the first time in this article. An inverted bistable quantizer is required due to use of a positive feedback in this noninterferometric optical implementation. The principles of the proposed optical first‐order and second‐order ADSM are modeled and analyzed. Two main components of the novel optical ADSM; the leaky integrator and the inverted bistable quantizer have been mathematically analyzed, simulated, and characterized. Finally, a prototype fiber‐optic ADSM is constructed. The prototype operates at MHz frequencies producing four effective‐number‐of‐bits resolution. The reported fiber‐optic ADSM is a very promising for future integration of this system on a photonic chip thus increasing the operation frequency range up to tens of GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1287–1292, 2012