Photonic Circuit Modulates RF Signals onto Optical Waveguides
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Solution Overview
Problem
Carrying radio frequency (RF) energy across distances in aircraft systems using coaxial cables is costly and complex due to the need for large, delicate bundles of cables, and optical connections have struggled to meet signal integrity requirements.
Innovation Solution
A photonic circuit that modulates RF signals onto optical signals using a wavelength-tunable laser and channels them using a filter array, integrated on a single chip, to provide channelized optical signals, reducing the need for bulky coaxial cables and improving signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bundles of coaxial cables are used to carry RF energy from antenna to electronic module, then signal transmission is achieved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces the mechanical/electrical coaxial cable system with an optical photonic circuit system. RF signals are converted to optical signals that travel through integrated photonic waveguides on a chip, eliminating the need for bulky coaxial cable bundles and their associated routing complexity through tight aircraft areas.
Solution Approach 2:
The patent integrates multiple functions (modulator, optical source, filter array) onto a single photonic chip. This merging of components that were previously separate and distributed along coaxial cables into one compact integrated circuit dramatically reduces manufacturing complexity and assembly steps.
2Reliability
If bundles of coaxial cables are used to connect antenna to electronic module, then RF energy transmission is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive coaxial cable bundles with an integrated photonic circuit that uses light to transmit RF information. The optical domain transmission through waveguides on a chip is inherently more cost-effective at scale than assembling and installing large bundles of delicate high-performance coaxial cables.
Solution Approach 2:
The patent changes the transmission medium from electrical (RF through coaxial cables) to optical (light through photonic waveguides). This parameter change enables the use of standard semiconductor manufacturing processes for producing the photonic chip, which are more cost-effective than the custom assembly required for coaxial cable bundles.
3Ease of operation
If coaxial cables are routed through tight and harsh areas of the aircraft, then connection between antenna and module is achieved, but installation and testing complexity increases
Solution Approach 1:
The patent nests the entire RF signal processing function within a compact photonic chip that can be easily mounted in accessible locations. The optical interconnections are embedded within the chip structure itself, eliminating the need to route delicate cables through tight and harsh aircraft areas where installation and testing would be tedious and complicated.
4Device complexity
If optical connections are used to replace coaxial cables, then manufacturing cost and complexity are reduced, but signal integrity requirements are difficult to meet
Solution Approach 1:
The patent merges the modulator, optical source, and filter array into a single integrated photonic circuit. This integration ensures that RF-to-optical conversion and signal filtering occur in a controlled, monolithic structure that maintains signal integrity while reducing the number of external optical connections that could introduce losses or interference.
Solution Approach 2:
The patent uses an integrated optical filter array as an intermediary between the RF modulation stage and the output. This filter array, fabricated as part of the photonic chip, selectively passes desired frequency components while blocking others, maintaining signal integrity without requiring additional external filtering components that would complicate the system.
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 photonic circuit enables efficient transmission of RF content in the optical domain, reducing manufacturing complexity and cost while maintaining high signal integrity, suitable for various applications including aircraft systems.
Implementation Method 1
The modulator and the optical source work together to modulate the radio frequency (RF) signals received from the circuit input onto the optical signals provided by the optical source
Implementation Method 2
the filter array includes a plurality of filters that channelize the optical signals received from the optical source in order to provide channelized optical signals
Data Source
AI summary
An integrated or monolithic photonic circuit that modulates RF signals onto optical signals and then performs a channelizing filter function according to the RF content. According to an exemplary embodiment, the photonic circuit is employed in an aircraft system that includes a front end, a photonic circuit, an optical connection, and an electronic module at some distant location in the aircraft. RF signals are received by an antenna in the front end, the RF signals are then modulated onto optical signals by a modulator and a laser, the modulated optical signals are filtered by a filter array according to a channelizing filter function, and the modulated and channelized optical signals are then carried over the optical connection to the electronic module. Other options like a wavelength-tunable laser and corresponding feedback feature, as well as ring filters with integrated semiconductor optical amplifiers (SOAs) are also possible.