Opto-Electronic Assembly with Silicon Submount for APD Alignment
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Solution Overview
Problem
Existing optical line card technologies face challenges in producing both passive and electro-optical elements efficiently, with monolithic and hybrid integration methods failing to achieve straightforward production of these components.
Innovation Solution
A hybrid integrated circuit with avalanche photodiodes and transimpedance amplifiers mounted on a common ceramic substrate, featuring an optical subassembly with an arrayed waveguide grating and turning mirrors, along with a temperature-control unit, which includes a silicon-based submount for height accommodation and independent thermal control to enhance optical coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate assemblies (transceiver, pluggable module, optics module, SFP cage) are used to implement line card functions, then functional versatility and adaptability are improved, but device complexity increases and space requirements expand
Solution Approach 1:
The patent combines the transceiver assembly, pluggable module, optics module, and SFP cage into a single integrated line card assembly. The transceiver is directly mounted on the line card PCB with the pluggable module positioned adjacent to it, eliminating the need for separate SFP cages and intermediate mounting structures. This merging reduces device complexity while maintaining all required functions.
Solution Approach 2:
The integrated line card assembly is designed to perform multiple functions simultaneously: the transceiver handles signal conversion, the pluggable module provides interface connectivity, the optics module enables optical communication, and the SFP cage structure is incorporated directly into the assembly. This multi-functional design achieves versatility without requiring separate specialized components.
2Adaptability or versatility
If multiple separate assemblies are used, then functional capabilities are improved, but the space occupied on the circuit board increases
Solution Approach 1:
The patent merges multiple functional assemblies into a compact integrated unit where the transceiver and pluggable module are positioned adjacent to each other on the same line card PCB. The optics module is integrated within this assembly, and the SFP cage structure is incorporated directly into the design. This consolidation significantly reduces the total space occupied compared to separate assemblies while maintaining all functional capabilities.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by positioning components in adjacent layers and orientations on the line card PCB. The transceiver and pluggable module are arranged to optimize space utilization, with connection terminals extending in different directions to minimize footprint. This dimensional optimization reduces the area occupied while preserving functional capabilities.
3Ease of manufacture
If conventional separate assemblies are used, then ease of manufacture is maintained, but manufacturing precision requirements increase due to alignment needs
Solution Approach 1:
The patent integrates the transceiver and pluggable module mounting structures directly into the line card PCB design, with connection terminals and mounting holes positioned in predetermined locations. This integrated design eliminates the need for separate alignment operations between multiple assemblies, reducing manufacturing precision requirements while maintaining ease of manufacture through standardized PCB fabrication processes.
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 enables efficient optical coupling and independent temperature control, reducing optical losses and fabrication complexities, thereby improving the performance and yield of optical receivers in line cards.
Implementation Method 1
The first planar substrate has a substantially different thermal expansivity than the second planar substrate. The first heater and the second heater are configured to be separately controllable.
Implementation Method 2
an array of avalanche photodiodes (APDs) that are electrically coupled to a corresponding array of transimpedance amplifiers (TIAs)
Data Source
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AI summary
In one embodiment, the opto-electronic assembly is a hybrid integrated circuit having an array of avalanche photodiodes (APDs) that are electrically coupled to a corresponding array of transimpedance amplifiers (TIAs), with both the APDs and TIAs being mounted on a common ceramic substrate. The opto-electronic assembly further has an optical subassembly comprising an arrayed waveguide grating (AWG) and an array of turning mirrors, both attached to a temperature-control unit in a side- by-side arrangement and flip-chip mounted on the substrate over the APDs. The opto-electronic assembly employs a silicon-based submount inserted between the APDs and the substrate to accommodate the height difference between the APDs and the TIAs. The submount advantageously enables the placement of APDs in relatively close proximity to the turning mirrors while providing good control of the APD's tilt and offset distance with respect to the substrate. The temperature-control unit enables independent temperature control of the AWG and of the array of turning mirrors, which helps to achieve good optical-coupling efficiency between the AWG and the APDs even when the turning mirrors have a relatively small size.