Abstract
Integrated photonic devices or circuits that can process the input electrical (digital) signal into optical output (analog) signal and vice versa are considered as the interfacing elements between electronic and photonic domains. Electro-optic digital-to-analog converters can be used as the building blocks for high-speed optical signal processing and high-speed communications between digital-electronic and analog-photonic domains. Efficient hybrid electro-optic digital-to-analog converters have the capability to overcome the issues of bandwidth limitations, electromagnetic noise, and timing jitter in traditional electronic digital-to-analog converters. Here, we present plasmonic digital to analog converters (PDACs) using broadband low-loss electro-absorption hybrid plasmonic switches with near epsilon zero nonlinearity of transparent conducting materials (TCOs). The electro-absorption switch consists of a hybrid plasmonic waveguide having a thin layer of a TCO (such as ITO). The optical losses in the plasmonic waveguide are controlled by changing the carrier concentration in the TCO layer. The free carrier density tunability effect in the metal-oxide-semiconductor (MOS) capacitor structure can be realized by applying an external voltage. The hybrid plasmonic waveguide-based electro-absorption switch shows very low insertion loss, high extinction ratio, high 3-dB bandwidth, ultra-compactness, low power consumption, very low-temperature sensitivity, and broadband optical operation. There is no previous report describing the design or fabrication of a plasmonic DAC. Moreover, to the best of our knowledge, PDACs based on the hybrid plasmonic switches — being proposed in this paper — have not been reported in any previous literature. We demonstrate a PDAC in a silicon photonics platform with high sampling rates, high nonlinearity, high resolutions, high precision, and low operating power.
Funder
Science and Engineering Research Board