INTEGRATION OF GRATING COUPLERS IN 2-STORY WAVE-GUIDES FOR ROTARY DISPLACEMENT SENSING

An integrated-optic device, constructed by stacking two types of grati ng coupler in a two-story structure of waveguides, is proposed for sen sing angular displacement of spindle rotation. in the first story a gu ided wave is diffracted by a grating coupler and becomes a sensing bea m. The sensing beam is reflected by a mirror with a quarter-wave plate attached to a spindle head and is coupled back into the second story by another grating coupler. We measured the rotary displacement of the spindle by detecting variation of polarization direction of the refle cted beam. A prototype device has been designed and fabricated, and th e operation principle is experimentally confirmed. (C) 1998 Optical So ciety of America.