Optical Injection Locking Source for EHF Signal Phase Noise Reduction
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Solution Overview
Problem
Extreme High Frequency (EHF) communication systems face challenges such as signal attenuation over coaxial cables, increased size, weight, and power consumption of RF components, and difficulties in downstream receiver processing, while optical systems are limited by chromatic dispersion and phase noise from laser sources.
Innovation Solution
A communications device utilizing an optical injection locking (OIL) source to amplify a selected harmonic of the modulated reference signal, allowing for efficient modulation and frequency conversion of EHF signals, which reduces signal degradation and increases operational flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical heterodyne approaches are used to transmit EHF signals, then signal transmission over long distances is improved, but phase noise of laser sources limits the system performance
Solution Approach 1:
The patent introduces an optical injection locking source as an intermediary component between the laser source and the modulator. This OIL source acts as a mediator that transfers the optical carrier signal while suppressing phase noise through injection locking mechanism, thereby improving signal quality without compromising transmission distance
Solution Approach 2:
The patent changes the operational parameters of the optical source by applying injection locking. This modifies the phase noise characteristics and frequency stability of the optical carrier, transforming it from a noisy source to a stable reference signal that enables high-fidelity EHF signal transmission
2Reliability
If chromatic dispersion compensation is implemented in optical systems, then signal fading is reduced, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-compensating for chromatic dispersion effects through the optical injection locking mechanism. The OIL source is configured to generate optical carriers with predetermined frequency characteristics that inherently compensate for dispersion-induced signal fading, eliminating the need for additional complex compensation devices
3Productivity
If RF components are used at EHF frequencies, then signal processing capability is improved, but size, weight, and power consumption increase to undesirable levels
Solution Approach 1:
The patent substitutes mechanical RF components with optical components for signal processing functions. By performing modulation and frequency conversion in the optical domain rather than using bulky RF hardware, the system achieves equivalent or superior signal processing capability while dramatically reducing size, weight, and power consumption
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 OIL source enhances signal distribution capabilities by providing greater conversion gain without noise penalties, enabling robust and efficient EHF signal transmission with reduced impact from amplitude fluctuations and phase noise.
Implementation Method 1
an optical injection locking (OIL) source coupled to the second E/O modulator and configured to amplify the modulated reference signal
Implementation Method 2
a first electro-optic (E/O) modulator 123 coupled to the optical source and modulating the optical carrier signal with an input signal
Implementation Method 3
an optical waveguide 129 coupled between the transmitter 121 and receiver devices
Implementation Method 4
an O/E converter coupled to the OIL source and configured to generate an output signal comprising a replica of the input signal
Data Source
AI summary
A communications device may include a remote device having a first E/O modulator to modulate an optical carrier signal with an input signal having a first frequency, an optical waveguide coupled to the remote device, and a local device coupled to the optical waveguide. The local device may include an optical source to generate the optical carrier signal, a second E/O modulator to modulate the optical carrier signal with a reference signal to generate a modulated reference signal, an OIL source coupled to the second E/O modulator and to amplify the modulated reference signal, and an O/E converter coupled to the OIL source and to generate an output signal including a replica of the input signal at a second frequency based upon the reference signal.