Optical Fiber Coupling Assembly for WDM Filter Incident Angle Control
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Solution Overview
Problem
Existing optical transceivers in WDM-PON systems are unable to sufficiently reduce unusable wavelengths between the C-band and L-band without increasing costs or causing unwanted back reflection, limiting the number of usable channel wavelengths.
Innovation Solution
An optical fiber coupling assembly with a dual core fiber pigtail and a gradient index (GRIN) lens is used to reduce the incident angle on the WDM filter, allowing for increased usable channel wavelengths without back reflection, by spacing the fiber cores and adjusting the GRIN lens pitch to control the incident angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the incident angle on the WDM filter is reduced to increase usable channel wavelengths, then the number of usable channels increases, but back reflection to the laser may occur
Solution Approach 1:
The patent introduces an optical fiber coupling assembly as an intermediary component between the laser and the WDM filter. This assembly includes a dual core fiber pigtail and a GRIN lens that work together to control the incident angle of light on the WDM filter, thereby reducing back reflection while maintaining increased channel wavelength usability.
Solution Approach 2:
The patent changes the incident angle parameter by using a dual core fiber pigtail with specifically spaced cores and a GRIN lens with a defined pitch. This parameter modification allows light to strike the WDM filter at an optimized angle that reduces back reflection while enabling the use of more channel wavelengths between the C-band and L-band.
2Productivity
If standard C-band and L-band transmissions are used, then the system is simple and cost-effective, but only 32 channels can be transmitted
Solution Approach 1:
The patent segments the optical fiber into a dual core fiber pigtail with two separately positioned cores. This segmentation allows independent control of light paths for different wavelength bands, enabling the system to handle more than 32 channels while managing the complexity through structured division of the fiber component.
Solution Approach 2:
The patent transitions from a single-core fiber to a dual core fiber pigtail, adding a spatial dimension to the optical path. The two cores are spaced at a specific distance apart, creating a two-dimensional arrangement that enables differentiation of wavelength paths and increases channel capacity beyond the standard 32 channels.
3Adaptability or versatility
If the number of channels is increased by reducing unusable wavelengths between C-band and L-band, then channel capacity increases, but the system complexity and cost increase
Solution Approach 1:
The optical fiber coupling assembly performs multiple functions: it couples optical fibers to transmitter and receiver sub-assemblies, controls the incident angle on the WDM filter, reduces back reflection, and enables increased channel wavelength usability. By consolidating these functions into a single integrated assembly, the patent increases adaptability while managing overall system complexity.
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 configuration enables the transceiver to transmit and receive at a higher number of channels in the C-band and L-band without significant back reflection, enhancing the performance and efficiency of WDM-PON systems.
Implementation Method 1
a gradient index (GRIN) lens is used to reduce the incident angle on the WDM filter
Implementation Method 2
a WDM filter that separates the wavelength(s) being transmitted by the transmitter sub-assembly from the wavelength(s) being received by the receiver sub-assembly
Implementation Method 3
An optical fiber coupling assembly includes a dual core optical fiber pigtail for coupling at least first and second optical fibers to an optical sub-assembly
Data Source
AI summary
An optical transceiver may include an optical fiber coupling assembly for coupling optical fibers to transmitter and receiver sub-assemblies to increase the number of usable channel wavelengths by reducing an incident angle on a WDM filter without causing unwanted back reflection to a laser. In one example, the optical fiber coupling assembly may be used to increase the number of usable channel wavelengths between the L-band and the C-band. The optical transceiver may be used, for example, in an optical line terminal (OLT) and/or optical networking unit (ONU) in a wavelength division multiplexed (WDM) passive optical network (PON) capable of transmitting and receiving optical signals on multiple channel wavelengths.