Abstract

Electro-optic traveling-wave modulators may be operated at high frequency with extremely large band widths. Important factors which limit the high frequency performance are the velocity mismatch (between the optical wave and the modulating microwave) and microwave loss. An analysis of the conventional directional coupler frequency response has already derived from the time-domain impulse response for the case of zero microwave loss, and a numerical analysis for the large signal frequency-domain response has also been given.¹ However, because the behavior of the directional couplers are nonlinear, the Fourier transformation of the time-domain impulse response is not generally a true frequency response. For analog operations there is a need for a small signal analysis in the frequency-domain to calculate the bandwidth. Further, general analysis of frequency response for other types of directional couplers such as 1 × 2 directional couplers² is also not available in the literature.

© 1991 Optical Society of America