Patent ID: 9172472
Filing Date: 2015-10-27
Classification: H04B

Abstract:
1. A method for modulating a carrier light wave so that a modulated light wave is achieved, the modulated light wave carrying information by means of symbols selected from a set of at least four different symbols, comprising: leading the carrier light wave through a modulating interferometer comprising respective first and second parallel-coupled waveguiding modulation paths; splitting the carrier light wave, and subsequently leading the split carrier light wave through said two paths, and then recombining the split carrier wave; and for modulating each respective symbol, between said splitting and said recombining, phase shifting the respective light led through each respective path by a respective total variable part phase shift, the total variable part phase shift for each path being the sum of at least three respective variable part phase shifts, wherein each respective variable part phase shift for each modulation state assumes one of two respective predetermined values, wherein each symbol in said set of symbols is modulated using a respective combination of two such total variable part phase shifts, wherein the modulation performed by the two paths is a PSK (Phase Shift Keying) scheme, wherein said set of symbols comprises 2 wherein the light led through each respective path is phase shifted using exactly 2 wherein the respective difference between the respective predetermined values is the same for all variable part phase shifts, wherein the two paths are also associated with a static phase shift offsetting the phase of the two paths compared to each other when recombined, and wherein the static phase shift offsets the phase of the two paths when recombined by ±π radians.