Submitted by Keysight Technologies

Historically, intensity modulation and direct detection have been used in optical communications to transmit information. This scheme is still used for short reach applications; however, the spectral efficiency and data rate is very limited. For example, a 100 Gbps signal using an intensity modulation scheme requires either very large bandwidth components or parallel transmission of several lower speed signals.

To support the high data rates required by today’s applications, modern communications systems must provide capabilities beyond traditional intensity modulation and direct detection schemes. Increasing demand for bandwidth has pushed the telecom industry to use coherent transmission techniques. Coherent data transmission takes advantage of amplitude, phase and polarization characteristics of light to enable transmission rates of 200 Gbps and more by transmitting complex symbols, each carrying multiple bits of information. 

In addition to speed, small size and low power consumption are key requirements for the circuit design. To address these needs, new integrated analog coherent optics modules (ACOs) and digital coherent optics modules (DCOs) have been developed and are being used in many network systems. The modules feature integrated abilities for both transmission and reception in a standardized pluggable module and include these sub systems: 

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By Larry Desjardin, Modular Methods

In October of this year, the AXIe Consortium, the VITA trade association, and six companies announced a new instrumentation standard called the Optical Data Interface, or ODI for short. The companies endorsing the standard were Conduant, Guzik, Intel, Keysight, Samtec, and Xilinx.

ODI shatters conventional distance and speed records.  Based on optical links between instruments, ODI can stream data up to 20 GBytes/s from a single optical port, with speeds up to 80 GBytes/s through port aggegation. It is a high-speed point-to-point interface that carries real-time signal data. The speeds, data formats, and timestamps are optimized for wide bandwidth multi-channel data, as found in 5G, radar, electronic warfare, and other RF applications. In October, I wrote gave a brief technical overview of the ODI standard, which you can read here. In this column I will dive deeper, and show some of the unique aspects of ODI that don’t exist in other instrument buses.

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