Northern Telecom Limited

Ivan Avrutsky

Jingming Xu

Hanan Anis

Toshi Makino

A superimposed grating tunable WDM semiconductor laser is provided comprising a grating structure is a binary superimposed grating comprising a plurality of segments of equal dimension, s, each segment having one of two values of refractive index, whereby the grating structure is provided by a binary modulation of the refractive index modulation of segments s along the length of the grating. Thus, for a superimposed grating structure for an optoelectronic device for providing a spectrum comprising j reflection peaks at wavelengths .lambda..sub.j, the grating comprising a binary superimposed grating (BSG) having a sequence of a plurality of segments of equal size s, each segment of the sequence having a refractive index of one of two values wherein the effective waveguide index of the ith segment n.sub.i.sup.0 (.lambda.) is allowed to be changed by .DELTA.n.multidot.(m-1/2) with m=1 or m=0: ##EQU1## where i=1,2,3 . . . is the segment number, for digital position i.multidot.s, n.sup.0 (.lambda.) is a waveguide effective index, including both waveguide and material dispersion, and the function f(x) is a weighted sum of sinusoidal functions of desirable period .LAMBDA..sub.j ##EQU2## and, periods .LAMBDA..sub.j relate to the spectral positions of reflection peaks .lambda..sub.j through the waveguide index n.sup.0 (.lambda.)

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Warren, MI, United States of America

Ivan Avrutsky