Off-Center Lens Cap for TO Can Laser Alignment
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Solution Overview
Problem
Industry-standard TO can laser packages face challenges in maintaining optical efficiency and alignment due to obstructions like pins/leads, causing laser diode displacement and misalignment with the optical axis of the lens cap, leading to signal quality degradation and increased costs from multiple design iterations.
Innovation Solution
Incorporating an off-center focus lens into the TO lens cap, which is offset to match the displacement of the laser diode, ensuring the focal point remains within tolerance and minimizing optical misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard TO can laser package is used with center-aligned lens cap, then manufacturing follows industry standards, but optical misalignment occurs due to laser diode displacement caused by pin/lead obstructions
Solution Approach 1:
The patent applies asymmetry by offsetting the lens cap from the center of the TO can package. Specifically, the lens cap is positioned at a distance of 0.06 inches from the centerline, which compensates for the 0.06-inch displacement of the laser diode caused by pin/lead obstructions. This asymmetric positioning restores proper optical alignment between the laser diode and lens cap while maintaining industry standard TO can package dimensions and lead configurations.
2Device complexity
If laser diode is directly coupled to leads without wire bonds, then electrical connections are simplified, but laser diode displacement occurs leading to optical axis misalignment
Solution Approach 1:
The patent converts the harmful effect of laser diode displacement into a beneficial design feature. Instead of treating the displacement as a defect to be corrected, the design intentionally positions the lens cap offset from center to match the displacement. This transforms the alignment problem caused by direct electrical coupling into a straightforward mechanical positioning solution, maintaining both electrical simplicity and optical precision.
3Reliability
If multiple design iterations are performed to compensate for alignment issues, then optical efficiency is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-positioning the lens cap with the correct offset during the initial package design phase. Rather than requiring multiple design iterations to correct alignment issues, the offset positioning is built into the fundamental package structure from the beginning. This single-step design approach achieves proper optical alignment without requiring subsequent redesign cycles, thereby maintaining high optical efficiency while minimizing design 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 solution enables long-distance transmissions exceeding 10 kilometers while adhering to industry standards, reducing optical power losses and manufacturing complexity, and allowing for the replacement of non-compensated TO can laser packages with minor modifications.
Implementation Method 1
the lens cap defining a cavity with a focus lens disposed therein for focusing laser light emitted by the laser diode along an optical axis of the focus lens
Data Source
AI summary
The present disclosure is generally directed to a TO can laser package that includes an off-center focus lens integrated into a lens cap to compensate displacement of an associated laser diode. The TO can laser package includes a TO header with a mounting structure for directly electrically coupling an associated laser diode to electrical leads/pins without the use of an intermediate interconnect. The mounting structure displaces the laser diode such that an emission surface, and more particularly, an origin thereof, is displaced/offset relative to a center of the TO header. The integrated lens cap includes a focus lens with an optical center that is offset from a center of the TO header at a distance that is substantially equal to the displacement of the laser diode. Thus, the displacement of the laser diode is compensated for by the off-center focus lens to minimize or otherwise reduce optical misalignment.