Optical Equalizer FIR Filter Multi-Stage Series
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Solution Overview
Problem
Existing optical equalizers face limitations in effectively addressing inter-symbol interference (ISI) due to bandwidth limitations of electro-optical components and optical fiber impairments like chromatic dispersion and polarization mode dispersion, often requiring complex designs and being temperature-dependent, which hinders their performance in optical communication networks.
Innovation Solution
An optical equalizer based on finite impulse response (FIR) filters with a multi-stage series configuration, utilizing passive waveguide delay lines and tunable couplers, such as directional and Mach-Zehnder Interferometer (MZI) couplers, to provide phase delay and amplitude adjustment, allowing for adaptive and temperature-independent operation, thereby overcoming various sources of ISI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical equalizers are used to overcome ISI, then equalization performance is improved, but device complexity and temperature sensitivity increase
Solution Approach 1:
The optical equalizer is divided into multiple discrete stages, each implementing a specific tap of the FIR filter. Each stage processes a portion of the signal with specific delay and weight, allowing modular design and independent optimization of each stage while achieving overall equalization performance.
Solution Approach 2:
The patent implements tunable couplers that can dynamically adjust the weight coefficients of each tap in response to temperature variations and signal conditions. This dynamic adjustment capability allows the equalizer to maintain optimal performance across different operating conditions without requiring complex temperature compensation circuits.
2Reliability
If conventional optical equalizers are used to overcome ISI, then equalization performance is improved, but power consumption increases
Solution Approach 1:
The patent replaces electrical domain equalization with optical domain equalization using all-optical components including waveguides, couplers, and phase shifters. This substitution eliminates the need for photo-detectors and electrical processing, significantly reducing power consumption while maintaining equalization performance.
3Reliability
If conventional optical equalizers are used to overcome ISI, then equalization performance is improved, but propagation loss increases
Solution Approach 1:
The equalizer is designed to perform equalization before the signal undergoes significant propagation loss in subsequent optical fiber transmission. By compensating for ISI and other impairments at the transmitter side, the signal maintains better quality throughout the transmission链路, reducing the need for additional amplification and re-transmission.
4Reliability
If conventional optical equalizers are used to overcome ISI, then equalization performance is improved, but device area increases
Solution Approach 1:
The patent implements a compact layout where multiple waveguide paths and couplers are nested within a small footprint. The sequential arrangement of stages allows previous stages to be spatially integrated with subsequent stages, maximizing the use of available space and reducing overall device area while maintaining the required number of taps and delay elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces power consumption, simplifies design, decreases propagation loss, and saves device area by enabling efficient ISI cancellation and phase tuning, making it suitable for advanced photonics systems in electro-optical communication networks.
Implementation Method 1
tunable couplers, such as directional and Mach-Zehnder Interferometer (MZI) couplers, to provide phase delay and amplitude adjustment
Implementation Method 2
utilizing passive waveguide delay lines and tunable couplers
Data Source
AI summary
The present disclosure provides an optical equalizer for photonics system in an electric-optical communication network. The optical equalizer includes an input port and an output port. Additionally, the optical equalizer includes a filter having a number of stages coupled to each other in a multi-stage series with an output terminal of any stage being coupled to an input terminal of an adjacent next stage while the input terminal of a first stage of the multi-stage series being coupled from the input port. Each stage includes a tap terminal configured to pass an optical power factored by a coefficient of multiplication from the corresponding input terminal of the stage to a tap-output path characterized by a corresponding phase delay. Furthermore, the optical equalizer includes a combiner configured to sum up the optical powers respectively from the number of tap-output paths of the multi-stage series to the output port.