Optical Waveguide Back Scattering Control via Phase Tuning
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Solution Overview
Problem
Current solutions for reducing back scattering in optical waveguide systems, such as optical isolators, are bulky, costly, and do not sufficiently improve back reflection without affecting optical signal quality, and existing methods to modify waveguide geometry or modes do not provide adequate reduction in back scattering.
Innovation Solution
A method and apparatus that injects light into an optical waveguide, taps off backscattered light, and uses a photodetector to measure and adjust the optical phase of the backscattered light, thereby controlling its power and reducing return loss through phase tuning and dithering, utilizing a controller and optical phase tuner to minimize back reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If optical isolators are used to suppress back reflections, then back scattering is reduced, but device size and cost increase significantly
Solution Approach 1:
The patent extracts only the essential function of back scattering suppression from the complex optical isolator system. Instead of using a complete optical isolator with multiple components (lenses, exotic materials, additional splices), the invention implements a simplified solution using a waveguide with integrated phase control elements that achieve the same back scattering reduction without the bulky external components.
Solution Approach 2:
The patent merges the back scattering suppression function directly into the waveguide structure itself. By integrating phase control elements (such as heaters or electro-optic modulators) within the waveguide, the system combines the functions of light guidance and back reflection suppression into a single integrated component, eliminating the need for separate optical isolators and external components.
2Object-affected harmful factors
If optical isolators are used to suppress back reflections, then back scattering is reduced, but system cost increases due to additional components and materials
Solution Approach 1:
The patent replaces expensive optical isolators with a more economical waveguide-based solution. The integrated phase control elements (such as resistive heaters or standard electro-optic modulators) are significantly cheaper than exotic materials and precision optical components required for traditional isolators, while achieving the same back scattering suppression.
Solution Approach 2:
The patent extracts the essential back scattering suppression function from the expensive optical isolator system and implements it using simpler, more cost-effective waveguide integration techniques, eliminating the need for costly external components, lenses, and exotic materials.
3Object-affected harmful factors
If waveguide geometry is changed to reduce back scattering, then back reflection is reduced, but optical signal quality may be affected
Solution Approach 1:
The patent employs dynamic phase control within the waveguide to manage back scattering. By using tunable phase shifters or electro-optic modulators that can be adjusted in real-time, the system dynamically adapts to maintain optimal optical signal quality while suppressing back reflections, rather than relying on fixed geometric modifications that would compromise signal integrity.
Solution Approach 2:
The patent changes operational parameters (such as phase shift, temperature, or electro-optic field strength) within the waveguide to control back scattering. This allows the system to maintain the waveguide's geometric integrity and optical signal quality while dynamically adjusting phase parameters to suppress back reflections through constructive and destructive interference control.
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
Significantly reduces back scattering in optical waveguide systems by effectively managing the optical phase of backscattered light, improving return loss by up to 30 dB or more, while maintaining optical signal quality and avoiding the need for bulky isolators or exotic materials.
Implementation Method 1
coupling the first tapped-off light into a first photodetector (PD); measuring a first electrical PD signal from the first PD, said first electrical PD signal being responsive to the first tapped-off light received by the first PD
Implementation Method 2
at least one optical phase tuner configured to act upon the at least one optical waveguide so as to vary an optical phase of light propagating therein at one or more locations along the at least one optical waveguide in response to one or more electrical control signals
Data Source
AI summary
Back scattering in an optical waveguide at an operating wavelength is controlled by adjusting an optical phase of light propagating in the waveguide at one or more locations along the waveguide. A portion of the back scattered light is tapped off near an input port and coupled into a photodetector. A controller detects changes in the photodetector signal and adjusts an optical phase tuner configured to control the optical phase of light in the waveguide at the selected location or locations. The optical phase tuner may be configured to vary the refractive index of at least a portion of the waveguide.