Chiral Fiber Grating Optical Coupler for Low-Loss Waveguide Interface
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Solution Overview
Problem
Existing optical fiber couplers face challenges in achieving low-loss, high-accuracy connections between dissimilar NA waveguides with closely spaced channels, particularly in interfacing conventional optical fibers with multichannel devices, leading to increased insertion losses and decreased coupling coefficients.
Innovation Solution
The development of an optical coupler array with a vanishing core waveguide and chiral fiber grating, which features a common housing structure with refractive index gradients and a chiral fiber grating for wavelength-selective coupling, allowing for precise control of light signal coupling across different waveguide modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional optical fiber couplers are used to interface dissimilar NA waveguides with closely spaced channels, then the device structure is simple, but insertion losses increase and coupling coefficients decrease
Solution Approach 1:
The coupler array is divided into multiple individual coupler elements, each handling specific waveguide pairs. This segmentation allows optimization of each element for low-loss coupling while maintaining overall system manageability and reducing total insertion loss across all channels.
Solution Approach 2:
Mode field adapter waveguides are introduced as intermediary elements between dissimilar NA waveguides. These adapter waveguides have intermediate NA values that gradually transition the mode field, acting as a mediator to reduce reflection and insertion loss while enabling coupling between waveguides with significantly different NA values.
2Measurement precision
If conventional optical fiber couplers interface dissimilar NA waveguides, then the manufacturing process is simple, but alignment accuracy decreases
Solution Approach 1:
Each coupler element is designed with locally optimized properties including specific NA values and mode field diameters tailored to the particular waveguide pairs it connects. This local quality optimization enables precise alignment and low-loss coupling for each specific interface, while the overall array can be manufactured using standardized processes.
Solution Approach 2:
The NA values and mode field diameters of the adapter waveguides are carefully selected and adjusted to match the specific requirements of the dissimilar waveguides being connected. By changing these optical parameters, the coupler achieves optimal alignment accuracy and coupling efficiency for each specific application.
3Quantity of substance
If closely spaced channels are used in multichannel devices, then the device density increases, but coupling coefficient decreases
Solution Approach 1:
The coupler array employs adjustable and configurable coupling elements that can be optimized for different channel spacings. The coupling strength and mode field overlap can be dynamically adjusted or selectively designed for specific spacing requirements, enabling high coupling coefficients even when channels are closely spaced.
Solution Approach 2:
The successful coupler element design is replicated and scaled across multiple channels in the array. By copying the optimized single-element design that achieves high coupling coefficient, the entire array maintains high coupling efficiency across all closely spaced channels while achieving high channel density.
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
This solution enables low-loss, high-coupling coefficient interfaces with improved alignment accuracy and wavelength-selective coupling, reducing crosstalk and enhancing the efficiency of optical signal transfer between diverse optical fibers and devices.
Implementation Method 1
a chiral fiber grating for wavelength-selective coupling, allowing for precise control of light signal coupling across different waveguide modes
Implementation Method 2
common housing structure with refractive index gradients
Data Source
AI summary
The present disclosure provides a pitch reducing optical fiber array or a multicore fiber including at least one chiral fiber grating incorporated therein that is operable to couple the modes in different fiber cores within a spectral range determined in some instances by the helical pitch of the corresponding chiral fiber grating.