Offset Lens Optical Module Reducing Return Loss
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Solution Overview
Problem
Existing optical receiver modules experience increased Optical Return Loss (ORL) due to the perpendicular entry of light beams onto the lens, leading to potential return light beams and reduced light receiving sensitivity.
Innovation Solution
The optical module design includes a substrate with an optical circuit element featuring a reflection plane that emits a collimated light beam at a 45° angle, with a support member positioning the light receiving element such that the light beam enters the lens at a perpendicular direction but with an offset optical axis, ensuring the light beam travels a shortest distance less than the Rayleigh length, thereby avoiding return light and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the light beam enters the lens perpendicularly at the top center, then the alignment is simple, but the Optical Return Loss increases due to return light beams
Solution Approach 1:
The patent applies asymmetry by intentionally offsetting the optical axis of the incident light beam from the top center of the lens. The light beam is designed to enter the lens at a position offset by a specific distance from the top center, rather than perpendicular at the center. This asymmetric configuration prevents the generation of return light beams that would cause high Optical Return Loss, while still maintaining simple alignment procedures.
2Manufacturing precision
If the light beam travels a longer distance to the lens, then the alignment tolerance is larger, but the light beam diverges and reduces receiving sensitivity
Solution Approach 1:
The patent applies parameter changes by optimizing the distance between the optical circuit element and the photo detector. The light beam is designed to travel a specific shortest distance (less than a preset value) to the lens, which is less than the Rayleigh length. This parameter optimization ensures that the light beam has not yet diverged significantly when reaching the lens, thereby maintaining high receiving sensitivity while allowing for practical alignment tolerances.
3Reliability
If the photo detector is positioned closer to the optical circuit element, then the light receiving sensitivity is higher, but the alignment precision requirement increases
Solution Approach 1:
The patent uses asymmetry in the optical path configuration, where the light beam offset distance from the lens top is specifically designed to be less than the lens curvature radius. This asymmetric arrangement allows the photo detector to be positioned at an optimized distance that balances receiving sensitivity with achievable alignment precision in manufacturing.
Solution Approach 2:
The patent optimizes the distance parameter between the optical circuit element and photo detector to be less than the Rayleigh length. This parameter change ensures that the light beam remains relatively collimated over the short distance, maintaining high receiving sensitivity while the short distance itself reduces the cumulative alignment precision requirements compared to longer paths.
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 reduces Optical Return Loss (ORL) and improves light receiving sensitivity by preventing return light beams and ensuring efficient light entry onto the lens before beam divergence, optimizing light detection.
Implementation Method 1
an optical circuit element (4) having an optical waveguide and a reflector, the optical waveguide being configured to propagate an optical signal in a propagation direction parallel to the base plane
Implementation Method 2
the reflector being configured to reflect an optical signal propagated through the optical waveguide and to output a reflected optical signal toward the substrate as a light beam
Implementation Method 3
a photo detector mounted on the base plane, the photo detector including a condenser lens and a light-receiving layer, the condenser lens being configured to converge the light beam onto the light-receiving layer
Data Source
AI summary
An optical module according to an aspect of the present disclosure includes a substrate having a base plane, an optical circuit element having an optical waveguide and a reflector, a support member, a photo detector mounted on the base plane, the photo detector including a condenser lens and a light-receiving layer. The light beam travels along an optical path from the reflector to the tangent plane, the optical path having a shortest distance set to be smaller than a preset value, and as viewed from a direction perpendicular to the base plane, the light beam has an optical axis set apart from the top of the condenser lens by an offset distance.