The second optical window may be formed in {HEAD ~ a straight line} with an optical input/output section formed in the memory die and {TAIL ~ the first optical window} 
The second optical window may be formed in { HEAD ~ a straight line } with an optical input / output section formed in the memory die and { TAIL ~ the first optical window }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL