Optical Isolator Layout for Reflected Return Light Absorption
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Solution Overview
Problem
Existing optical isolators suffer from scattering of reflected return light within the housing, which adversely affects isolation characteristics and reliability.
Innovation Solution
Incorporating an absorbing member in the optical path of reflected return light to redirect and absorb at least part of the reflected light, using structures such as grooves, bores, or surface-treated layers to attenuate the light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reflected return light is blocked by the first polarizer, then isolation characteristics are improved, but reflected return light scatters in the housing interior becoming stray light that degrades reliability
Solution Approach 1:
The harmful reflected return light is extracted from the main optical path by the first polarizer, separating it from the transmitted light. The absorbing member then extracts this separated reflected light from the housing interior, preventing its harmful scattering effects while maintaining the isolation function.
Solution Approach 2:
The absorbing member acts as an intermediary element positioned between the first polarizer and the housing wall. It intercepts the reflected return light before it can scatter throughout the housing interior, absorbing or attenuating it to prevent stray light formation while allowing the main optical function to proceed unchanged.
2Reliability
If an absorbing member is added to absorb reflected return light, then stray light is reduced improving reliability, but device complexity increases
Solution Approach 1:
The absorbing member serves multiple functions simultaneously: it absorbs reflected return light to prevent stray light, defines the optical path boundary, and can be integrated with existing housing structures. This multi-functionality justifies the addition by providing several benefits from a single component.
Solution Approach 2:
The absorbing member can be merged with the housing structure itself, such as making the housing wall partially absorbing or integrating the absorbing material into existing components. This combination approach reduces the number of separate parts while maintaining the stray light suppression function.
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
Reduces scattering of reflected return light within the housing, enhancing the reliability and isolation characteristics of the optical isolator.
Implementation Method 1
a Faraday rotator disposed between the first polarizer and the second polarizer
Implementation Method 2
an absorbing member that absorbs at least part of the reflected return light is provided in an optical path of the reflected return light
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
Provided is an optical isolator that can reduce scattering of reflected return light in the interior of the housing and thus has excellent reliability. An optical isolator 1 includes: a first polarizer 2 provided on a light incidence side in a direction X of an optical axis; a second polarizer 3 provided on a light exit side in the direction X of the optical axis; a Faraday rotator 4 disposed between the first polarizer 2 and the second polarizer 3; and a housing 6 containing the first polarizer 2, the second polarizer 3, and the Faraday rotator 4, wherein the first polarizer 2 is configured that reflected return light A having transmitted the second polarizer 3 and the Faraday rotator 4 is reflected in a different direction from the direction X of the optical axis, and an absorbing member 5 that absorbs at least part of the reflected return light A is provided with an absorbing member 5 that absorbs at least part of the reflected return light A in an optical path of the reflected return light A having reflected in the different direction from the direction X of the optical axis.