A photonic analog-to-digital converter using phase modulation and self-coherent detection with spatial oversampling

Area of Science:

• Photonics
• Integrated Optics
• Signal Processing

Background:

• Photonic analog-to-digital converters (ADCs) are crucial for high-speed signal processing.
• Existing photonic ADCs face challenges in achieving both high resolution and high sampling rates simultaneously.
• Temporal oversampling is a common technique to enhance ADC resolution, but it increases sampling rate requirements.

Purpose of the Study:

• To propose and demonstrate a novel photonic ADC architecture.
• To leverage spatial oversampling for enhanced conversion resolution.
• To achieve high-resolution (>7 bit) and high sampling rates (tens of GS/s) for gigahertz signals.

Main Methods:

• Encoding analog voltage signals onto the phase of optical pulses from a mode-locked laser.
• Implementing spatial oversampling using a LiNbO(3)/silica hybrid photonic integrated circuit.
• Experimentally digitizing gigahertz signals at an undersampled rate.

Main Results:

• Demonstrated digitization of signals up to 18 GHz at a 2.56 GS/s undersampled rate.
• Achieved a conversion resolution of up to 7.6 effective bits.
• Successfully demonstrated spatial oversampling with oversampling factors of 1-4.

Conclusions:

• The proposed photonic ADC with spatial oversampling is a viable approach for high-resolution, high-speed signal conversion.
• Spatial oversampling offers an alternative to temporal oversampling for improving ADC resolution.
• This technology has potential applications in high-frequency signal acquisition and processing.