TOSA with Vertically-Mounted Monitor Photodiodes
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Solution Overview
Problem
The existing TOSA designs face challenges in reducing housing dimensions and improving RF drive signal quality due to the placement of monitor photodiodes, which increases manufacturing complexity and cost, and results in longer housing lengths and impedance issues.
Innovation Solution
The TOSA housing incorporates vertically-mounted monitor photodiodes with a feedthrough device that allows for modular manufacturing and reduces housing dimensions by positioning the photodiodes above the laser diodes, enabling shorter wire bonds and improved RF signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If monitor photodiodes are mounted in traditional positions (behind or adjacent to laser diodes), then optical power monitoring is achieved, but housing length increases and RF signal quality deteriorates due to longer wire bonds
Solution Approach 1:
The patent applies vertical mounting of monitor photodiodes on the side walls of the TOSA housing, transitioning from traditional horizontal/adjacent placement to a vertical configuration. This dimensional change allows the photodiodes to be positioned above the laser diodes through optical coupling, thereby reducing the horizontal footprint and housing length while maintaining monitoring functionality.
Solution Approach 2:
The patent introduces optical intermediaries (such as optical windows or coupling structures) that enable light transmission from the laser diodes to the vertically-mounted photodiodes. This intermediary mechanism allows optical power monitoring without requiring direct physical contact or adjacent positioning, thus resolving the conflict between monitoring accuracy and compact housing dimensions.
2Measurement precision
If monitor photodiodes are mounted in traditional positions, then optical power monitoring is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
By mounting photodiodes vertically on side walls rather than horizontally behind or adjacent to laser diodes, the patent simplifies the manufacturing process. This vertical configuration allows for more straightforward assembly and reduces the complexity of aligning and positioning components within the housing, thereby lowering manufacturing complexity and cost.
3Measurement precision
If wire bonds are made longer to connect photodiodes in traditional positions, then optical power monitoring is achieved, but RF signal quality and impedance matching deteriorate
Solution Approach 1:
The vertical mounting configuration positions photodiodes closer to the laser diodes in three-dimensional space, enabling shorter wire bonds or trace connections. This reduced connection length minimizes RF signal degradation and impedance matching issues, thereby improving RF signal quality while maintaining optical power monitoring capability.
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 the overall housing dimensions, decreases manufacturing time and cost, and enhances RF signal quality by allowing for closer proximity of conductive traces to the laser diodes, thereby reducing time-of-flight delays and impedance matching issues.
Implementation Method 1
each light receiving region optically coupled to a back-side emission surface of a corresponding laser diode
Implementation Method 2
monitor photodiodes... having a light receiving region
Data Source
AI summary
The present disclosure is generally directed to a multi-channel TOSA with vertically-mounted MPDs to reduce TOSA housing dimensions and improve RF driving signal quality. In more detail, a TOSA housing consistent with the present disclosure includes at least one vertical MPD mounting surface that extends substantially transverse relative to a LD mounting surface, with the result being that a MPD coupled to the vertical MPD mounting surface gets positioned above an associated LD coupled to the LD mounting surface. The vertically-mounted MPD thus makes regions adjacent an LD that would otherwise be utilized to mount an MPD available for patterning of conductive RF traces to provide an RF driving signal to the LD. The conductive RF traces may therefore extend below the vertically-mounted MPD to a location that is proximate the LD to allow for relatively short wire bonds therebetween.