BOSA Housing Integration for Thermal Management in ONUs

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Solution Overview

Problem

Optical network units (ONUs) in multi-channel bi-directional optical subassemblies face challenges in reducing cost and enhancing thermal conduction efficiency, particularly due to the need for separate housings for transmitter optical subassemblies (TOSAs) and the complexity of thermal management in densely packed systems.

Innovation Solution

A single housing for both the transmit and receive optical subassemblies (TOSAs and ROSAs) with integrated thermal management, using a stainless steel or Kovar housing to encompass the components, including a thermistor and thermoelectric cooler for temperature control, eliminates the need for additional housing and improves heat distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate hermetically sealed housing is used for the TOSA, then the laser is protected from environmental factors, but the manufacturing cost increases and thermal management efficiency decreases

Engineering Contradiction:

Improvelaser protectionVSAvoidhousing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the TOSA housing with the ONU housing into a single integrated structure. The TOSA is mounted directly on the ONU circuit board within the ONU housing, eliminating the need for a separate hermetically sealed TOSA housing. This integration maintains laser protection while reducing manufacturing complexity and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ONU housing serves multiple functions: it protects the ONU circuit board, provides structural support, and now also houses the TOSA laser assembly. This multi-functional design eliminates the need for dedicated separate housings for each component, reducing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a separate hermetically sealed housing is used for the TOSA, then the laser is protected from environmental factors, but the manufacturing cost increases

Engineering Contradiction:

Improvelaser protectionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the TOSA housing function with the ONU housing, eliminating the need for separate hermetically sealed enclosures. The TOSA is mounted directly on the ONU circuit board within the existing ONU housing, reducing the number of components and assembly steps, thereby lowering manufacturing cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the hermetic sealing requirement from the TOSA housing and applies it only where necessary (at the laser aperture and fiber coupling points). This selective approach maintains laser protection while eliminating unnecessary hermetic sealing of entire separate housings, reducing manufacturing complexity and cost.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If traditional boxed TOSA design is used, then the laser is protected, but thermal management effectiveness decreases due to additional insulating layers

Engineering Contradiction:

Improvelaser protectionVSAvoidthermal management

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent merges the thermal management function directly with the ONU housing structure. The housing is designed with thermally conductive features that provide direct thermal pathways from the TOSA laser to the housing, eliminating insulating layers and improving heat dissipation efficiency.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ONU housing acts as an intermediary thermal management component, providing direct thermal coupling between the TOSA laser and the external environment. This intermediary structure replaces traditional insulating housing designs with a thermally conductive path that actively manages laser temperature.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces manufacturing complexity and costs, enhances thermal management efficiency, and maintains precise wavelength control for optical signals, addressing the challenges of cost reduction and thermal management in ONU systems.

Implementation Method 1

a thermistor and thermoelectric cooler for temperature control

Methodology Applied

Scientific EffectPeltier effect: Peltier Effect

Implementation Method 2

using a stainless steel or Kovar housing to encompass the components... improves heat distribution

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9432122B2Optical networking unit (ONU) packaging

Publication Date: 2016.08.30 APPLIED OPTOELECTRONICS INC(US)

AI summary

A bidirectional optical subassembly (BOSA) optical networking unit (ONU) generally includes a BOSA housing. A tunable laser is located in the BOSA housing and is configured to generate a first optical signal for transmission at a first selected wavelength based on temperature control. The tunable laser is a distributed feedback (DFB) laser diode. A thermal management device is also located in the BOSA housing and is configured to provide the temperature control. A photo diode is further located in the BOSA housing and is configured to receive a second optical signal at a second selected wavelength. The BOSA housing comprises an alloy of stainless steel or an alloy of Kovar.