Balanced Opto-Electrical Oscillator for Laser Noise Rejection
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Solution Overview
Problem
Existing opto-electronic oscillators face significant noise contributions from laser amplitude noise, which limits their phase noise performance, as the equivalent noise associated with the laser is an order of magnitude greater than the input-referred current noise of the electrical circuitry.
Innovation Solution
An opto-electrical oscillator design featuring first and second optical phase modulators, a coupler, and optical-to-electrical signal converters, with a control circuit causing the feedback signals to be out of phase, effectively reducing laser amplitude noise by utilizing balanced optical signal processing paths and common mode rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional opto-electronic oscillator design is used, then the oscillator can generate oscillating signals for various applications, but the laser amplitude noise significantly degrades the phase noise performance
Solution Approach 1:
The single optical path is segmented into two balanced optical paths (first and second optical paths) that process signals differentially. This segmentation allows the system to separate and independently process signals while rejecting common-mode noise components, including laser amplitude noise, thereby improving phase noise performance.
Solution Approach 2:
The patent converts the harmful laser amplitude noise into a beneficial effect by using it as a common-mode signal that is rejected through the balanced differential architecture. The noise that would normally degrade performance is instead cancelled out through the out-of-phase combination of the two optical paths.
2Object-generated harmful factors
If balanced optical signal processing paths are implemented, then laser amplitude noise is reduced through common mode rejection, but the device complexity increases
Solution Approach 1:
The patent merges the two balanced optical paths at the coupler, combining multiple optical signals into a single output path. This merging approach allows the system to achieve noise rejection through differential processing while consolidating the optical paths, thereby reducing the overall complexity compared to maintaining completely separate processing chains.
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 balanced design significantly reduces noise immunity, achieving lower phase noise and improved performance by rejecting noise components associated with the optical source, particularly the laser amplitude noise.
Implementation Method 1
The first optical phase modulator is adapted to modulate the phase of a first optical signal in response to a first feedback signal to generate a first phase modulated signal
Implementation Method 2
The first optical-to-electrical signal converter is adapted to receive an optical signal from a first output port of the coupler
Implementation Method 3
The coupler has first and second input ports that receive the first and second phase modulated signals
Data Source
AI summary
An opto-electrical oscillator includes, in part, first and second optical phase modulators, a coupler, an optical-to-electrical signal conversion circuit, and a control circuit. The first optical phase modulator modulates the phase of a first optical signal in response to a first feedback signal to generate a first phase modulated signal. The second optical phase modulator modulates the phase of a second optical signal in response to a second feedback signal to generate a second phase modulated signal. The first and second optical signals travel through first and second optical paths respectively and are generated from the same optical source. The optical-to-electrical signal conversion circuit receives an optical signal from the coupler and in response generates an electrical signal applied to the control circuit. The output signals of the control circuit cause the first and second feedback signals to be out of phase.