Synthesis of amplitude response of optical directional coupler modulators

Optical directional coupler modulator amplitude response may be synthesized using the Gel´fand-Levitan-Marchenko inverse scattering technique. The technique determines the coupling function required to obtain the specified response, and for this summary we illustrate it with the response function of a third order Butterworth function. The technique provides the possibility of designing coupler modulators with small switching voltages, and better linearity.