Variable Optical Attenuator Arrays With Retroreflector
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Solution Overview
Problem
Existing fiber optic networking systems face challenges in precisely controlling optical signal levels, particularly in adjusting power levels for optical test systems and signal routing systems, due to the inherent variability of laser outputs and the need for long-distance communication emulation.
Innovation Solution
A variable optical attenuator (VOA) with a retroreflector and an array of VOAs is introduced, where each VOA includes input and output fibers connected on the same side, allowing for compact design and independent control of attenuator elements before and after reflection, thereby enabling precise optical power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional fiber optic systems use separate input and output fiber connections, then signal transmission is reliable, but the system size and complexity increase
Solution Approach 1:
The patent combines input and output fiber connections on the same side of the VOA device, merging what were traditionally separate connection points into a unified interface. This allows both input and output fibers to be accessed from one side, reducing the overall system footprint and simplifying cable management while maintaining reliable signal transmission through the retroreflector-based optical path.
Solution Approach 2:
The patent introduces a retroreflector to change the optical path geometry, allowing light to travel through the attenuator element and return through the same or parallel path. This dimensional change in the optical path enables compact arrangement of components on one side, reducing the linear footprint of the device while maintaining functional separation of input and output signals.
2Adaptability or versatility
If multiple fiber bends are introduced in traditional VOA configurations, then connection flexibility is improved, but reliability decreases due to increased signal loss
Solution Approach 1:
The patent performs preliminary routing of both input and output fibers on the same side before they enter the VOA housing. This preliminary arrangement minimizes the need for sharp bends within the device itself, as fibers can be gently routed from the connection point on one side through the attenuator and retroreflector assembly, reducing stress and signal loss while maintaining installation flexibility.
3Device complexity
If laser output power is not controlled, then system simplicity is maintained, but precise optical power control is lost
Solution Approach 1:
The patent employs an attenuator element whose transmission characteristics can be dynamically adjusted by changing physical parameters such as the position of the element in the optical path or its material properties. This allows precise control of optical power levels by modifying the attenuation parameter, enabling accurate emulation of long-distance fiber transmission losses while maintaining a relatively simple device structure.
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 allows for increased granularity and control of optical signal attenuation, reduces the size and complexity of VOA arrays, enhances reliability by minimizing fiber bends, and facilitates easier connectivity and maintenance.
Implementation Method 1
a retroreflector to receive a light beam from the input fiber and reflect the light beam to the output fiber
Data Source
AI summary
A variable optical attenuator (VOA) may include an input collimator with an input fiber connected on one side and an output collimator with an output fiber connected on one side, where the collimators are on a same surface of a VOA enclosure. A retroreflector may receive a light beam from the input collimator and reflect the light beam to the output collimator. The VOA may include an attenuation element positioned between the input collimator and the retroreflector and/or another attenuation element positioned between the retroreflector and the output collimator to provide variable attenuation to the light beam. The attenuation elements may be moved to set an attenuation level by one or more adjustment elements such as a miniature motor. The attenuation element may include a gradient index (GRIN) element, a polarizer, a neutral density filter, or a wavelength tunable filter.