Cascade circuit architecture for RF-photonic frequency multiplication with minimum RF energy

TL;DR

This paper introduces a cascaded Mach-Zehnder modulator architecture for RF-photonic frequency multiplication that significantly reduces RF energy consumption and improves efficiency without requiring optical filtering or precise modulation adjustments.

Contribution

The paper presents a novel cascade circuit design for RF-photonic frequency multiplication with lower RF energy requirements and enhanced efficiency compared to traditional parallel configurations.

Findings

Achieves frequency multiplication factor of 2N with N cascaded modulators.

Reduces RF energy input compared to parallel MZM configurations.

Improves conversion efficiency by 5 dB over existing designs.

Abstract

A general RF-photonic circuit design for implementing frequency multiplication is proposed. The circuit consists of N cascaded differentially-driven Mach-Zehnder modulators biased at the minimum transmission point with a progressive RF phase shift of 180/N applied to each stage. The frequency multiplication factor obtained is 2N. The novelty of the design is the reduced input RF energy required in comparison to the functionally equivalent parallel MZM configuration. Using transfer matrix method, a N=3 architecture is modeled to obtain frequency sextupling. An industry standard simulation tool is used to verify the architectural concepts and analysis. The proposed design requires no optical or electrical filtering nor careful adjustment of the modulation index for correct operation. In addition, the overall intrinsic conversion efficiency of the N=3 cascade circuit is improved by 5 dB over a parallel MZM circuit. Finite MZM extinction and/or phase errors and power imbalances in the electric drive signals are also taken into consideration and their impact on overall performance investigated. The circuit can be integrated in any material platform that offers electro-optic modulators.