Here are the citations linked to Poet's most relevant Patent. I'm astouned by the amount of times Apple inc. has been citing this. It seems to me that they might use their interposer to build a miniature all-in-one photonic integrated oxymeter. But I thought you also needed red light for the hemogoblin not just 2 infrared sources. Can you make an oxymeter with infrared only?
Here's a link to the patent in case the image doesn't work. https://patents.google.com/patent/US9880352B2/en?assignee=poet+technologies&oq=poet+technologies#citedBy