Systems and methods for in-phase and quadrature modulation

An In-phase and Quadrature (IQ) modulator system comprising:

• a digital signal processor (DSP) configured to process In-phase digital signals and Quadrature digital signals, in which the processing of the In-phase digital signals and the Quadrature digital signals includes:
• providing a first delay to at least one of the In-phase digital signals and the Quadrature digital signals;
• combining the In-phase digital signals and the Quadrature digital signals to generate a complex digital signal;
• modulating upper side band (USB) frequency components of the complex digital signal by a first pilot-tone (PT) frequency signal and generating PT modulated time domain samples corresponding to the USB frequency components;
• modulating lower side band (LSB) frequency components of the complex digital signal by a second PT frequency signal and generating PT modulated time domain samples corresponding to the LSB frequency components;
• combining the PT modulated time domain samples corresponding to the USB frequency components and LSB frequency components and generating combined PT modulated time domain samples;
• splitting the combined PT modulated time domain samples into PT modulated In-phase digital signals and PT modulated Quadrature digital signals;
• wherein, if the In-phase digital signals were provided with the first delay, providing a second delay to the PT modulated In-phase digital signals and if the Quadrature digital signals were provided with the first delay, providing the second delay to the PT modulated Quadrature digital signals;
• and
• converting the PT modulated In-phase digital signals and the PT modulated Quadrature digital signals into corresponding PT modulated In-phase analog signals and PT modulated Quadrature analog signals;
• an optical modulator comprising:
• an input optical port configured to receive an optical signal;
• an arm coupled to the input optical port, the arm including:
• a plurality of radio frequency (RF) electrodes coupled to the DSP and configured to modulate the optical signal in accordance with the PT modulated In-phase analog signals and the PT modulated Quadrature analog signals and generate PT modulated In-phase optical signals and PT modulated Quadrature optical signals;
• a plurality of DC voltage bias electrodes configured to bias the PT modulated In-phase optical signals and the PT modulated Quadrature optical signals to a null point;
• a phase bias electrode configured to adjust a phase bias point of the PT modulated Quadrature optical signals and generating phase adjusted PT modulated Quadrature optical signals such that a phase difference between the PT modulated In-phase optical signals and the phase adjusted PT modulated Quadrature optical signals is 90°;
• and
• a combiner configured to combine the PT modulated In-phase optical signals and phase adjusted PT modulated Quadrature optical signals signal and generate a combined PT modulated optical signal to be transmitted towards a receiver.