All-optical analog comparator.

Area of Science:

• Photonics
• Optical Computing
• Semiconductor Devices

Background:

• Analog comparators are crucial for all-optical analog-to-digital conversion (AO-ADC).
• Existing AO-ADC systems often rely on electrical comparators, contradicting the goal of all-optical devices.
• A true all-optical comparator is needed to achieve complete optical signal processing.

Purpose of the Study:

• To propose and numerically demonstrate a novel all-optical analog comparator.
• To enable true all-optical analog-to-digital conversion without electrical components.
• To characterize the performance of the proposed all-optical comparator.

Main Methods:

• Numerical demonstration of an all-optical analog comparator.
• Utilizing a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures.
• Analysis of the comparator's transfer function and operational characteristics.

Main Results:

• The proposed device functions as an all-optical analog comparator.
• Achieved low threshold power (mW range) and high extinction ratio (up to 40 dB).
• Demonstrated fast operation rate (tens of Gb/s) and a step-like transfer function suitable for binarization.

Conclusions:

• The developed all-optical comparator is well-suited for true AO-ADC systems.
• Enables complete digitization of analog optical signals into binary representations within the optical domain.
• Offers significant advantages in speed, power consumption, and signal fidelity for optical computing applications.