Integrated Depolarizer Circuit Using Delay Lines to Minimize Interference
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Solution Overview
Problem
Existing depolarizers are expensive, bulky, and suffer from interference effects, limiting their practical applications in photonic systems.
Innovation Solution
A depolarizer circuit comprising an input waveguide, splitter, rotators, delay lines, and a combiner, which minimizes interference by ensuring a phase delay difference greater than the coherence of the light source, allowing for incoherent coupling and effective depolarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional depolarizers (Cornu, Lyot, Wedge) are used, then depolarization function is achieved, but device cost and size increase significantly
Solution Approach 1:
The depolarizer is segmented into multiple integrated waveguide paths with different polarization states and delay times. Each waveguide branch processes a specific polarization component, and the segments are recombined at the output to achieve depolarization. This segmentation allows the complex depolarization function to be distributed across simpler, integrated components.
Solution Approach 2:
The patent replaces mechanical or bulky optical components with an integrated photonic circuit implementation. Instead of using physical rotating elements or large optical assemblies, the depolarization is achieved through waveguide-based polarization manipulation and interference control, substituting mechanical systems with solid-state photonic integration.
2Reliability
If active phase shifters and feedback control signals are used, then polarization control is improved, but interference effects increase
Solution Approach 1:
The patent extracts and eliminates the active phase shifter and feedback control signal components from the system. By removing these elements, the source of interference effects is taken out, while the essential polarization control function is maintained through passive waveguide-based polarization manipulation and fixed delay line configurations.
Solution Approach 2:
The patent converts the potential harmful interference effects into a beneficial mechanism by carefully designing the delay lines to create controlled interference patterns that enhance depolarization. The fixed path length differences between waveguide branches are designed to exploit interference constructively for depolarization rather than as unwanted noise.
3Device complexity
If integrated photonic circuit is used, then device size is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The waveguide structures in the integrated circuit are designed to serve multiple functions simultaneously: guiding light, maintaining specific polarization states, providing fixed delay times, and enabling interference control. This multi-functionality reduces the need for separate components and relaxes individual precision requirements while maintaining overall system performance.
Solution Approach 2:
The patent utilizes changes in waveguide parameters (such as length, width, and material composition) to achieve the required polarization and delay control. By carefully selecting and adjusting these geometric and material parameters during design, the system achieves precise control without requiring extremely tight manufacturing tolerances, as the design compensates for typical fabrication variations.
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 provides improved depolarization with minimized interference, enabling efficient use in optical interrogators and optical gyroscopes.
Implementation Method 1
a splitter connected to the input waveguide and configured to provide, at a first output of the splitter, light in a first polarization state and, at a second output of the splitter, light in a second polarization state
Implementation Method 2
a first rotator connected to the first output of the splitter and configured to rotate light received therefrom from the first polarization state to the second polarization state
Implementation Method 3
the first and second delay lines provide a phase delay difference there between being greater than or equal to a coherence of the light source
Implementation Method 4
a combiner connected to the second rotator and the second delay line and configured to combine light received from each thereof as depolarized light
Data Source
AI summary
Provided herein is a depolarizer circuit having an input waveguide configured to receive light from a light source; a splitter configured to provide light from the input waveguide in a first and second polarization states; a first rotator configured to rotate the light from the first polarization state to the second polarization state; a first delay line configured to delay the light in the second polarization state; a coupler configured to couple the rotated and delayed light; a second rotator configured to rotate the coupled light back to the first polarization state; a second delay line configured to delay the coupled light in the second polarization state; and a combiner configured to combine light from second rotator and delay line as depolarized light, where the first and second delay lines provide a phase delay difference therebetween greater than or equal to a coherence of the light source.