Optical Transceiver Equalization for Fiber Dispersion Recovery
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Solution Overview
Problem
High-speed optical communication systems using multimode fibers face challenges in transmitting signals due to dispersion and limited frequency bandwidth of electrical signal lines and semiconductor devices, which existing compensation techniques, such as pre-emphasis and pre-compensation, struggle to address effectively, especially when considering the interaction between transmitters and receivers.
Innovation Solution
An optical transceiver design with two equalizer units: one in the transmitter to compensate frequency distortion caused by limited bandwidth of electrical signal lines and semiconductor devices, and another in the receiver to compensate dispersion of the optical fiber, with a method to set tap coefficients for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical equalizing is provided only in the receiver, then device complexity is reduced, but signal distortion compensation ability is insufficient due to limited frequency bandwidth of electrical signal lines and semiconductor devices
Solution Approach 1:
The equalization function is segmented into two separate equalizer units: a first equalizer unit in the transmitter and a second equalizer unit in the receiver. Each equalizer unit independently compensates for different aspects of signal distortion, with the first equalizer addressing transmitter-side limitations and the second equalizer addressing receiver-side and fiber dispersion effects.
2Reliability
If pre-compensation technique is used to compensate whole distortion and dispersion, then compensation completeness is improved, but thermal conditions for devices become harsh due to large power requirements
Solution Approach 1:
The compensation task is divided between transmitter and receiver equalizer units, allowing each to operate with smaller, more manageable power requirements rather than concentrating all compensation power in a single pre-compensation stage.
Solution Approach 2:
The first equalizer unit in the transmitter performs preliminary equalization of the electrical signal before optical conversion, reducing the burden on the receiver equalizer and enabling more effective overall compensation without excessive power consumption.
3Ease of manufacture
If multimode fiber is used for easy coupling, then ease of manufacture is improved, but transmission speed is limited due to dispersion
Solution Approach 1:
The system changes the electrical signal parameters through equalization to compensate for the dispersion effects in multimode fiber, effectively extending the usable bandwidth and enabling higher transmission speeds over the existing multimode infrastructure.
Data Source
AI summary
An optical transceiver and a method to setup the optical transceiver are disclosed, where the transceiver has a function to compensate the distortion and the dispersion due to the limited bandwidth of the electrical signal line, that of the active devices, and that of the optical fiber. The optical transceiver comprises a transmitter with an equalizer unit and a receiver also with an equalizer unit. The equalizer unit in the transmitter compensates the distortion due to the limited bandwidth of the transmission lines for the electrical signal and that of the semiconductor active device, while, the equalizer unit in the receiver compensates the dispersion due to the limited bandwidth of the optical fiber.