Digital-to-analog converters are indispensable functional units in signal transmission and also an essential part of the optical computing. In previous systems, the conversion of a digital electronic signal to an analog optical signal has been achieved by first converting the digital electronic signal to an analog electronic signal and then converting the analog electronic signal to an optical analog signal with an electro-optic modulator. This approach has a drawback which requires summing in electronics where it is difficult to achieve linear sums at high speed with varying voltage or current.
Researchers at GW have developed a novel optical digital to analog converter. The invention eliminates the need for an electronic digital to analog converter, thereby reducing both the complexity of optical analog systems and noise. A light source (form of information) is passed through coupling onto the chip, where the light is split by a series of serial 3 dB couplers. The resulting modulated optical signals are combined in binary tree of 3 dB optical combiners.
Figure 1. A logical diagram of the invention
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