Mendes S B, Li L, Burke J J, Lee J E, Saavedra S S
Appl Opt. 1995 Sep 20;34(27):6180-6. doi: 10.1364/AO.34.006180.
We report a general approach to the design of broadband waveguide couplers. A double-parallel grating assembly is used to cancel the first chromatic order, and a proper choice of prism glass and base angle is made to compensate for the second chromatic order. The technique was applied to a Corning glass 7059 waveguide, and a spectral bandwidth of 70 nm was measured by the use of two complementary procedures.