Performance analysis of an all-optical logic gate based on a single I/Q modulator with direct detection

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Digital Optics

Background:

• All-optical logic gates offer high-speed computation potential.
• In-phase and quadrature (I/Q) modulators are key components in optical signal processing.
• Direct detection schemes simplify optical receiver design.

Purpose of the Study:

• To investigate the performance of an all-optical logic gate scheme utilizing a single I/Q modulator with direct detection.
• To develop a new theoretical model for the I/Q modulator in this context.
• To analyze the impact of key system parameters on the performance metrics of extinction ratio (ER) and Q-factor.

Main Methods:

• Theoretical modeling of the I/Q modulator.
• Numerical simulations of an OR logic gate.
• Analysis of performance metrics (ER and Q-factor) under varying system parameters like phase shift, Mach-Zehnder modulator (MZM) extinction ratios, laser output power, and MZM insertion loss.

Main Results:

• The system's extinction ratio is influenced by the phase shift and MZM extinction ratios.
• The Q-factor is affected by laser output power and MZM insertion loss.
• For a 20 dB MZM extinction ratio, a minimum laser output of 3 dBm is needed for ER > 16 dB, and >10 dBm for Q-factor > 6.

Conclusions:

• The proposed all-optical logic gate scheme is simple, high-speed, and reconfigurable.
• Optimal design of the laser, I/Q modulator, and RF module is essential for best performance.
• Specific laser power requirements are identified for achieving desired ER and Q-factor performance levels.