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<!-- Generated by Broadridge Transform (tm) - http://www.broadridge.com -->
<!-- Created: Fri Apr 24 18:34:01 UTC 2026 -->
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    <loc xlink:type="locator" xlink:label="aaoi_ExclusionOfStockAwardsAndOptionAwardsMember" xlink:href="aaoi-20251231.xsd#aaoi_ExclusionOfStockAwardsAndOptionAwardsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllAdjToCompMember" xlink:to="aaoi_ExclusionOfStockAwardsAndOptionAwardsMember" order="5" xbrldt:closed="true"/>
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