Abstract

The 'external' grating coupler is a diffraction grating pressed against the planar waveguide in a similar way as a prism coupler. Such couplers have, to the best of our knowledge, not been used in integrated optics. The couplers normally used are surface relief gratings on the waveguide. We report on a new type of optical bistability (OB) which occurs only with external but not with normal grating couplers. The air gap of width d, where 0≤d≤λ, plays an essential role in the OB mechanism.

© 1988 Optical Society of America