Patent ID: 9369211
Filing Date: 2016-06-14
CPC Classification: H04B

Claim Text:
1. An optical communication method, comprising: converting an optical pulse amplitude modulation (PAM) signal to a square QAM signal using an optical delay interferometer (DI) to perform all-optical PAM to QAM conversion in the DI without requiring an I/Q modulated signal as input; performing optical de-correlation of I and Q tributaries of the QAM signal to avoid frequency dependent attenuation in RF cabling which impacts signal quality; monitoring and equalizing down-converted I and Q electrical signal amplitudes, using coherent detection; and emulating a square quadrature amplitude modulation (QAM) optical signal with duplicated data copies, wherein the delayed interferometer provides signal decorrelation between the I and Q signal lanes at integer symbol length to emulate an optical QAM signal and using PAM modulation rate at the same baud rate as a QAM output signal and using an optical intensity modulator instead of an optical IQ modulator for an optical QAM emulation.