Patent ID: 9104085
Filing Date: 2015-08-11
Classification: G02F,H04B

Abstract:
1. Method for modulating a carrier light wave so that a modulated light wave is achieved, which modulated light wave carries information by means of symbols selected from a set of at least two different symbols, wherein the carrier light wave is led through a modulating interferometer comprising a respective first, second, third and fourth parallel-coupled waveguiding modulation path, wherein the carrier light wave is first split, subsequently led through said four paths and then recombined, wherein for modulating each respective symbol the respective light led through each respective path, between the said split and the said recombining, is phase shifted by a respective total path phase shift, which total path phase shift is the sum of a possible respective first, second, third or fourth static phase shift and a respective first, second, third or fourth variable modulating phase shift amount, and wherein each symbol in the said set of symbols is associated with a respective combination of such total phase shift amounts, characterized in that, for at least two of the symbols in said set of symbols there is defined a respective first non-zero pair phase shift amount, a respective second non-zero pair phase shift amount and a respective non-zero common phase shift amount, in that, for each of said at least two symbols, the absolute value of said first pair phase shift amounts are equal, the absolute value of said second pair phase shift amounts are equal and the absolute value of said common phase shift amounts are equal, and in that, for each of said at least two symbols, the first respective variable modulating phase shift amount is equal to the sum of the respective first pair phase shift amount and the respective common phase shift amount; the second respective variable modulating phase shift amount is equal to the sum of the negative of the respective first pair phase shift amount and the respective common phase shift amount; the third respective variable modulating phase shift amount is equal to the sum of the respective second pair phase shift amount and the negative of the respective common phase shift amount; and the fourth respective variable modulating phase shift amount is equal to the sum of the negative of the respective second pair phase shift amount and the negative of the respective common phase shift amount.