Optical Transmitter RF Path Stacked With Laser Package
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Solution Overview
Problem
Current optical transmitters with high-speed data communication requirements, such as 40 Gb and 100 Gb transmission rates, face challenges in fitting all components within the small form factor of transceivers like QSFP, QSFP28, and SFP due to limited space, which complicates the integration of RF and optical signal paths.
Innovation Solution
The optical transmitter design incorporates an RF signal path that is parallel and vertically stacked with the optical signal path, using an electrical transmission element like a flex PCB to transmit RF data signals to an optical modulator, allowing both signals to be received and modulated within a compact form factor, thereby reducing the size and complexity of the enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional optical transmitter design is used with separate RF and optical signal paths, then signal transmission function is achieved, but device size becomes too large to fit in small form factor transceivers
Solution Approach 1:
The patent transitions from a planar arrangement of RF and optical signal paths to a three-dimensional stacked configuration. The RF signal path and optical signal path are arranged in different vertical layers, allowing both paths to coexist within a compact footprint that fits small form factor transceivers while maintaining signal integrity and functional separation.
Solution Approach 2:
The patent nests the RF signal path components within the same enclosure as the optical signal path components. The RF transmission element and modulator are positioned in overlapping spatial regions with the optical components, creating a nested arrangement that maximizes space utilization and reduces overall device volume.
2Volume of moving object
If components are densely packed to reduce size, then form factor is reduced, but thermal management becomes difficult
Solution Approach 1:
The patent implements localized thermal management by providing dedicated cooling structures specifically for the laser assembly. The enclosure includes thermal vias, heat sinks, or thermoelectric coolers positioned in close proximity to the laser, ensuring efficient heat dissipation from this critical component while other parts of the compact device maintain their dense packaging.
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
Described herein is an optical transmitter that includes an RF signal path that is, at least partially, parallel with an optical signal path. In one embodiment, an electrical transmission element, which defines the RF signal path, is disposed between a laser emitting the optical signal and a side wall of a package containing the optical transmitter. Although the RF and optical signals may propagate along different planes within the optical transmitter, both signals are received at an optical modulator. Using the RF signal, the optical modulator modulates the optical signal (e.g., a continuous wave) to generate a modulated optical signal. The optical modulator then outputs the modulated signal to a receptacle coupled to a light carrying medium such as a fiber optic cable.