Digitization method for a photonic analog-to-digital converter with phase-shifted optical quantization

Area of Science:

• Photonics
• Electrical Engineering
• Signal Processing

Background:

• Photonic analog-to-digital converters (ADCs) are crucial for high-speed signal processing.
• Traditional direct digitization methods face challenges with excessive bit width and invalid code generation.
• Phase-shifted optical quantization (PSOQ-ADC) offers potential for improved performance.

Purpose of the Study:

• To introduce a novel matrix digitization method for PSOQ-ADCs.
• To address limitations of existing direct digitization techniques.
• To demonstrate the effectiveness of the proposed method in digitizing radio frequency (RF) signals.

Main Methods:

• Development and implementation of a matrix digitization technique for PSOQ-ADCs.
• Fabrication of a PSOQ-ADC on a lithium niobate on insulator (LNOI) platform.
• Experimental setup to digitize RF signals using a 50 GS/s optical pulse train.

Main Results:

• Successful digitization of 1/2/5 GHz RF signals using the matrix digitization method, yielding 5-bit codes without invalid outputs.
• The matrix digitization method produced fewer invalid codes compared to the direct digitization method, even at lower optical signal-to-noise ratios (OSNR).
• The effective number of bits (ENOB) for the matrix digitization method surpassed that of the direct digitization method, even with error correction.

Conclusions:

• The proposed matrix digitization method is a viable and superior alternative for PSOQ-ADCs.
• This method effectively overcomes the limitations of traditional direct digitization, offering higher accuracy and reliability.
• The LNOI-based PSOQ-ADC with matrix digitization shows promise for advanced high-speed signal processing applications.