Photonic Integrated Circuit with Delayed Feedback for RF Signal Processing
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Solution Overview
Problem
Existing optical processing devices are limited in their ability to process a wide range of digitally modulated optical signals and RF-modulated signals, and they struggle to improve transmission reliability over larger distances with conventional digital signal processors.
Innovation Solution
A photonic integrated circuit with parallel optical signal processing units, each comprising an optical filter device and an optical delay element, operates in a recurrent mode to coherently combine modulated carrier signals with externally delayed feedback, allowing spectral filtering and delayed feedback to enhance frequency and time-dependent processing, with tunable center frequencies and group delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional digital signal processors are used for optical signal processing, then processing functionality is provided, but computation bandwidth is limited and transmission reliability over long distances deteriorates
Solution Approach 1:
The patent replaces conventional electronic signal processing with photonic integrated circuit processing. The PIC processes optical signals directly in the optical domain using photonic components (modulators, detectors, waveguides) rather than converting to electrical signals for digital processing. This substitution enables higher computation bandwidth and improved transmission reliability over long distances by eliminating the bandwidth limitations of electronic processors.
2Adaptability or versatility
If optical processing devices are used to process a wide range of digitally modulated optical signals, then processing capability is improved, but device complexity increases
Solution Approach 1:
The photonic integrated circuit is designed as a universal processing platform that can handle multiple signal types and processing functions through a single integrated device. The PIC incorporates tunable components (such as programmable modulators and detectors) that can be reconfigured to process different modulation formats and signal characteristics, eliminating the need for multiple specialized devices and reducing overall system complexity.
3Device complexity
If serial processing architecture is used with identical MRRs, then processing structure is simple, but signal attenuation increases and processing capabilities are limited
Solution Approach 1:
The patent divides the processing function into multiple parallel processing units within the photonic integrated circuit. Each unit can independently process signal components, and the parallel architecture allows signals to be processed simultaneously across multiple paths. This segmentation reduces the cumulative attenuation effect compared to serial processing while maintaining manageable complexity through modular unit design.
4Ease of operation
If weighted waveguide connections are used between successive MRRs, then signal processing is enabled, but cumulative insertion losses attenuate the optical input signal
Solution Approach 1:
The patent merges multiple processing functions into a single integrated photonic circuit with shared optical paths and common resource elements. By combining filtering, modulation, detection, and signal processing functions in one device, the system eliminates the need for multiple separate components with their associated connection losses. The integrated architecture reduces cumulative insertion losses while maintaining full signal processing capability.
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 enables superior preprocessing of optical input signals, achieving low-latency parallel processing, increased detectable optical power, and improved transmission reliability over longer distances with reduced complexity and energy consumption.
Implementation Method 1
an optical filter device and an optical delay element arranged externally to the filter device. The delay element is connected to an input port and an output port of the filter device and provides an externally delayed feedback signal to the filter device
Implementation Method 2
The group delay induced by the delay element is comprised in the range from 1 ps to 100 ps
Implementation Method 3
An input section of the delay element is configured to coherently combine the modulated carrier signal with the externally delayed feedback signal to create a new filter input signal
Data Source
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AI summary
A photonic integrated circuit (100) for performing optical transient computing on an RF-modulated optical carrier signal (106), a signal processing device (110) comprising the same, and a related processing method. The photonic circuit comprises at least two optical signal processing units (101), each including a filter device (103) and a delay element (102) for providing a delayed feedback signal to the filter device. The group delay induced by the delay element is in the range from 1 ps to 100 ps and the 3 dB bandwidth of the filter band is less than the inverse of the group delay. The delay element is adapted to spectrally align at least a portion of the filter band with a resonance in the feedback signal and center frequencies of filter bands are offset between 1 GHz and 100 GHz to allow filtering of different portions of the modulated carrier signal spectrum. The signal processing device has a trainable readout circuit (117).