GRATING COUPLER DISPERSION COMPENSATION WITH A SURFACE-RELIEF REFLECTION GRATING

Experimental results are presented that show that diffraction off a surface-relief reflection grating can be used to extend the FWHM input coupling efficiency versus the coupled-light wavelength of a grating coupler from 0.7 to 17 nm. Use of a surface-relief reflection grating allows high diffraction efficiency over a wide wavelength range. Dispersion-matching calculations are included that illustrate that for certain output coupling applications the FWHM can be extended to 33 nm. Analysis shows that for input-coupling applications the lateral beam shift resulting from angular dispersion may be the limiting factor for wavelength compensation.