Lossless 0th and −1st order switching by dual-excitation of grating waveguide mode

Abstract

The reflected 0th and −1st diffraction orders of a waveguide grating can be switched between 0 and 1 diffraction efficiency upon the excitation of a forward- and backward-propagating waveguide mode by means of the +1st and −2nd orders. Such mode-coupling trigger of high isolation switching is found to be in the neighborhood of the −1st order Littrow condition under the condition that no transmitted order can propagate; the condition is here fulfilled without loss penalty by reflecting them under total internal reflection. This requires a waveguide refractive index larger than 3, and resorting to a semiconductor in the near infrared. This non-Fano phenomenon is yet another feature of resonant gratings. The reflective switching effect lends itself to a stable monolithic implementation, and can be used for wavelength control, or for the evanescent wave sensing of measurands in the transmission medium.

Differential Sensing with Replicated Plasmonic Gratings Interrogated in the Optical Switch Configuration

“…Recently, a new surface plasmon detection configuration termed the “optical switch” [ 23 , 24 , 25 ] was proposed and justified theoretically [ 26 ] as a promising method of detection based on a grating coupler. This approach involves monitoring two diffracted orders, the st and the 0th diffracted orders, produced by the interaction of an incident light beam with a deep metal grating.…”