Analysis of Trade-offs in RF Photonic Links based on Multi-Bias Tuning of Silicon Photonic Ring-Assisted Mach Zehnder Modulators

TL;DR

This paper analyzes multi-bias tuning in silicon photonic RAMZMs to optimize RF photonic link performance, demonstrating significant improvements in linearity, gain, and noise figure through biasing strategies.

Contribution

It introduces a comprehensive analysis of multi-bias tuning in RAMZMs, deriving performance metrics and proposing biasing schemes for enhanced RF photonic link performance.

Findings

18 dB/Hz^{2/3} SFDR improvement with RAMZM linearization

6x slope efficiency increase and 15.56 dB gain over MZMs

Method to enhance gain in photodiode saturation limited links

Abstract

Recent progress in silicon-based photonic integrated circuits (PICs) have opened new avenues for analog circuit designers to explore hybrid integration of photonics with CMOS ICs. Traditionally, optoelectronic systems are designed using discrete optics and electronics. Silicon photonic (SiP) platforms provide the opportunity to realize these systems in a compact chip-scale form factor and alleviate long-standing challenges in optoelectronics. In this work, we analyze multi-bias tuning in Ring-Assisted Mach Zehnder Modulator (RAMZM) and resulting trade-offs in analog RF photonic links realized using RAMZMs. Multi-bias tuning in the rings and the Mach-Zehnder arms allow informed trade-offs between link noise figure and linearity. We derive performance metrics including gain, noise figure, and linearity metrics associated with tuning of multiple bias settings in RAMZM based links and present resulting design optimization. Compared to MZM, an improvement of 18 dB/Hz$^{\frac{2}{3}}$ in SFDR is noted when RAMZM is linearized. We also propose a biasing scheme for RAMZM that provides 6x improvement in slope efficiency, or equivalently, 15.56dB in power Gain over MZMs (single drive) while still providing similar SFDR performance ($\sim$ 109 dB/Hz$^{\frac{2}{3}}$) as MZMs. Moreover, a method to improve gain in photodiode saturation limited links is presented and studied.