Enhancing Vector Network Analysis With a Photonic Frequency Extender Setup

TL;DR

This paper introduces a photonic frequency extender for vector network analyzers that significantly broadens measurement capabilities into the terahertz range, reducing system complexity and cost.

Contribution

The paper presents a novel photonic frequency extension method for VNAs, enabling ultra-wideband measurements up to 520 GHz and beyond without additional extender modules.

Findings

Achieved measurements from 70 GHz to 520 GHz with Hz resolution.

Demonstrated extension to 1 THz using cascaded lasers.

Validated measurements against simulations and commercial extenders.

Abstract

We present a photonic ultra-wideband frequency extension for a commercial Vector Network Analyzer (VNA) to perform free-space measurements in a frequency range from 70 GHz up to 520 GHz with a Hz level resolution. The concept is based on the synchronization of continuous-wave (CW) lasers with highly frequency-stable electronic emitter sources as a reference. The use of CW photomixers with bandwidths up to several terahertz allows for the straightforward expansion of the covered frequency range to 1 THz or even beyond. This can be achieved, for instance, by cascading additional lasers within the synchronization scheme. Consequently, the necessity for additional frequency extender modules, as seen in current state-of-the-art VNAs, is eliminated, thereby reducing the complexity and cost of the system significantly. To showcase the capabilities of the Photonic Vector Network Analyzer (PVNA) extender concept, we conducted S21 transmission measurements of various cross-shaped bandpass filters and waveguide-coupled high-frequency (HF) components. Additionally, the analyzed magnitude and phase data were either compared to electro-magnetic (EM) simulations or referenced against data obtained from commercial electronic frequency extender modules.