Dual frequency comb assisted analog-to-digital conversion

Abstract

Photonic analog to digital conversion offers promise to overcome the signal-to-noise ratio and sample rate trade-off in conventional analog to digital converters (ADCs), critical for modern digital communications and signal analysis. We propose using phase-stable dual frequency combs with a fixed frequency spacing offset to downconvert spectral slices of a broadband signal and enable high-resolution parallel digitization. To prove the concept of our proposed method, we demonstrate the detection of a 10 GHz subcarrier modulated (SCM) signal using 500 MHz bandwidth ADCs by optically converting the SCM signal to 10 1 GHz bandwidth signals that can be processed in parallel for full signal detection and reconstruction. Using sinusoidal-wave-based standard ADC testing, we demonstrate a spurious-free dynamic range of > --> 45 d B and signal-to-noise-and-distortion of > --> 20 d B , limited by the receiver front-end design.