Light Emitting Module Dual Lens Alignment
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Solution Overview
Problem
In light emitting modules for optical communication systems, improving light coupling efficiency between semiconductor light emitting elements and optical fibers is challenging due to positional shifts and alignment accuracy issues, particularly when using a single condenser lens, which affects the back focus and decentering of the meniscus lens.
Innovation Solution
A light emitting module configuration using two lenses, where the first lens collimates light from the semiconductor light emitting element, and the second meniscus lens, with a specific curvature radius profile, condenses this light to improve alignment accuracy and reduce decentering effects, thereby enhancing light coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single condenser lens is used, then the device complexity is reduced, but the light coupling efficiency decreases due to positional shifts and alignment accuracy issues
Solution Approach 1:
The patent divides the optical system into two separate lenses: a collimator lens and a condenser lens. This segmentation allows each lens to perform its specific function optimally, with the collimator lens handling beam collimation and the condenser lens handling light condensation, thereby improving alignment tolerance and coupling efficiency while maintaining manageable system complexity
Solution Approach 2:
The collimator lens acts as an intermediary element between the semiconductor light emitting element and the condenser lens. By introducing this intermediate optical component, the system achieves better alignment accuracy and reduces the impact of positional shifts on the final light coupling efficiency
2Measurement precision
If the curvature radius of the condenser lens is increased to reduce decentering effects, then the alignment accuracy improves, but the back focus length increases
Solution Approach 1:
The patent optimizes the curvature radius parameter of the condenser lens to achieve a balance between alignment accuracy and back focus length. By carefully selecting and adjusting this geometric parameter, the system reduces decentering effects and improves alignment tolerance while maintaining an acceptable back focus length for practical applications
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
The proposed configuration significantly reduces the decrease in light coupling efficiency caused by decentering, achieves a longer back focus, and maintains high alignment accuracy, leading to improved optical performance and efficiency in light transmission.
Implementation Method 1
The first lens is optically coupled to the semiconductor light emitting element to collimate light output from the semiconductor light emitting element
Implementation Method 2
The second lens is a meniscus lens. The meniscus is optically coupled to the semiconductor light emitting element through the first lens to condense the collimated light
Data Source
AI summary
A light emitting module including a semiconductor light emitting element, a first lens, a second lens, and an optical fiber stub, is disclosed. The first lens collimates light output from the semiconductor light emitting element. The second lens is a meniscus lens and condenses the collimated light to the optical fiber stub. A light entering surface of the second lens has a cross-sectional shape in which an increase rate of a curvature radius is zero or more. A light exiting surface of the second lens includes a first region and a second region. The first region has a cross-sectional shape in which a sign of the increase rate of the curvature radius is positive. The second region surrounds the first region and has a cross-sectional shape in which a sign of the increase rate of the curvature radius is negative.