The splitting ratios are selected so that a strong signal will have enough energy for detection along the entire waveguide path. A cascaded array of beamsplitters and detectors splits the power of an incoming optical signal into multiple channels by specific splitting ratios that correspond to a digital representation of the signal.

The all-optical A/D converter concept is illustrated in Figure 1. Moreover, all-optical converters eliminate the complexity and speed limitation of electrical-to-optical and optical-to-electrical conversions in photonic networks. Optical A/D converters offer better performance than their electronic counterparts because optical signals are not subject to electronic noise and radiation, and are thus immune to electromagnetic interference. Optical or optoelectronic converters have received significant interest in areas such as telecommunication, sensors, and imaging.

The emergence of high-speed parallel digital optical systems requires an all-optical analog-to-digital (A/D) converter.

Analogue to digital optical converter