Dual-wavelength sub-Nyquist sampling scheme for clipping-avoidance photonic ADC.

Area of Science:

• Photonics
• Electrical Engineering
• Signal Processing

Background:

• Photonic analog-to-digital converters (PADCs) face challenges with signal clipping, especially at high sampling rates.
• Sub-Nyquist sampling offers advantages in reduced hardware complexity and power consumption.
• Existing methods for clipping avoidance in PADCs often require complex circuitry or specific operating conditions.

Purpose of the Study:

• To propose and experimentally validate a dual-wavelength scheme for clipping-avoidance in PADCs operating at sub-Nyquist sampling rates.
• To leverage the phase-wrapping and wavelength-sensitive properties for effective modulo operation.
• To enable reliable signal reconstruction independent of the sampling rate.

Main Methods:

• A dual-wavelength scheme employing phase modulation and a dual-modulus (DM) modulo operation was developed.
• An unwrapping algorithm based on the Chinese Remainder Theorem (CRT) was integrated for signal reconstruction.
• Proof-of-concept experiments were conducted on a PADC chip fabricated on a Lithium Niobate on Insulator (LNOI) platform.

Main Results:

• The proposed scheme successfully avoided clipping in the PADC.
• 1G/2G/4G-baud 10-level pulse amplitude modulation (PAM-10) waveforms were accurately reconstructed.
• Reconstruction was achieved at sub-Nyquist sampling rates of 1/2/4 Gs/s, demonstrating the scheme's effectiveness.

Conclusions:

• The dual-wavelength scheme offers a viable solution for on-chip clipping-avoidance in PADCs.
• The integration of CRT-based unwrapping ensures robust signal reconstruction.
• This approach facilitates high-performance PADC operation at sub-Nyquist sampling rates.