Granted Patent
Utility
US 5,930,422 · App. 09/198,500
Optical circulator
Inventor:
Yihao Cheng
Patented Case
View Patent ↗
Granted: Jul 27, 1999
Filed: Nov 24, 1998
Inventor
Yihao Cheng
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.