Photonic monobit analog-to-digital converter using coherent detection

A method for generating a digital signal representative of an input complex baseband signal, the method comprising:

• modulating phase and amplitude of an input optical signal using the input complex baseband signal to generate an optical modulated signal;
• coupling the optical modulated signal with an optical noise signal to generate a dithered optical signal, the optical noise signal comprising random signal phases that are uniformly distributed over a pre-determined range of the optical noise signal, and the dithered optical signal having a sour free dynamic range (SFDR) based on the uniformly distributed random signal phases of the optical noise signal;
• coherently detecting a dithered in-phase (I) signal component and a dithered quadrature (Q) signal component associated with the input complex baseband signal using the dithered optical signal and a reference optical signal;
• generating a complex decision signal based on limiting the dithered I and Q signal components;
• and
• generating a digital signal representative of the input complex baseband signal based on the complex decision signal.

A photonic monobit analog-to-digital converter, comprising:

• an optical source configured to generate an optical noise signal, the optical noise signal comprising random signal phases that are uniformly distributed over a pre-determined range of the optical noise signal;
• a filter configured to generate a filtered noise signal using the generated optical noise signal;
• a dual optical modulator configured to modulate phase and amplitude of an input complex baseband signal onto an input optical signal to generate an optical modulated signal;
• a coupler configured to couple the optical modulated signal with the filtered noise signal to generate a dithered optical signal, the dithered optical signal having a spur-free dynamic range (SFDR) based on the uniformly distributed random signal phases of the optical noise signal;
• a coherent detector configured to coherently detect a dithered in-phase (I) signal component and a dithered quadrature (Q) signal component associated with the input complex baseband signal using the dithered optical signal and a reference optical signal;
• a limiter configured to output a complex decision signal based on the dithered I and Q signal components;
• and
• a digital signal processing (DSP) circuit configured to generate a digital signal representative of the input complex baseband signal based on the complex decision signal.