Travelling-wave integrated-optical modulator with spread frequency response

Summary form only given. The authors fabricated planar electrode structures for travelling-wave integrated optical modulators which allow the spread of the FR (frequency response) and simultaneous decrease of drive power in a fixed-frequency band. This is achieved by a smooth change of value and sign or electrooptical interaction according to the appropriate functional dependence, which, in the absence of microwave losses, is related by Fourier transform to the magnitude FR (MFR) and phase FR (PFR) of the modulator. Taking into account a rectangular MFR and quadratic PFR, a chirped oscillating dependence of the electrooptical interaction efficiency along the waveguide was obtained by inverse Fourier transform. A 1-cm-long triangular toothed electrode structure makes it possible to obtain a uniform broadband MFR up to 160 GHz with six times less drive power than with a conventional electrode, and an 8-mm-long trapezoidal toothed electrode structure makes it possible to obtain a uniform bandpass modulation in the 80-160-GHz range.<
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