Patent ID: 7469075

Claim:
A method for increasing the resolution of a digital phase modulator for a fiber-optic signal transmission or measuring device, having a total number m of positive and negative electrodes of different lengths which are arranged parallel and on both sides of a light guiding path in or on an optical substrate to which identical control potentials can be applied, which, depending on the position of the electrodes with respect to the light guiding path, effect a positive or negative shift in the light phase output of the modulator, a multiplicity of phase values being set in accordance with combinations of positively and negatively acting electrodes within a predetermined value range, characterized in that the total number m of electrodes is divided into groups, from a first group n of electrodes forming a coarse modulator with binary and, in terms of their contribution to the light phase shift, more significant weighted electrodes with a length ratio of b n+1 :bn≈2 being formed, and from a second group of n 0 non-binary and, in terms of their contribution to the light phase shift, less significant weighted electrodes a fine modulator being formed, at least one electrode of said fine modulator being positioned on the side of the longest electrode of the coarse modulator, and the lengths on the light phase shift of the electrodes arranged on different sides of the fine modulator being selected to be greater than the resolution of the overall modulator and the smallest phase modulation steps being generated by simultaneous driving of positive and negative electrodes of the fine modulator or of the fine modulator and of the coarse modulator.