In-situ optical vector analysis based on integrated lithium niobate single-sideband modulators

TL;DR

This paper presents a compact, broadband optical vector analysis system using integrated lithium niobate SSB modulators, enabling in-situ characterization of photonic devices with high precision and revealing their intrinsic properties.

Contribution

The work introduces a miniaturized, in-situ optical vector analysis system based on broadband SSB modulators on a lithium niobate platform, capable of directly measuring amplitude and phase responses of integrated photonic devices.

Findings

Achieved kHz-level resolution and tens of THz bandwidth in measurements.

Successfully characterized on-chip microring resonators and their coupling states.

Demonstrated in-situ measurement of phase dynamics and density of states in a synthetic frequency crystal.

Abstract

Optical vector analysis (OVA) is an enabling technology for comprehensively characterizing both amplitude and phase responses of optical devices or systems. Conventional OVA technologies are mostly based on discrete optoelectronic components, leading to unsatisfactory system sizes, complexity, and stability. They also encounter challenges in revealing the on-chip characteristics of integrated photonic devices, which are often overwhelmed by the substantial coupling loss and extra spectral response at chip facets. In this work, we demonstrate a miniaturized OVA system for integrated photonics devices based on broadband single sideband (SSB) modulators on a thin-film lithium niobate (LN) platform. The OVA could provide a direct probe of both amplitude and phase responses of photonic devices with kHz-level resolution and tens of terahertz measurement bandwidth. We perform in-situ characterizations of single and coupled microring resonators fabricated on the same chip as the OVA, unfolding their intrinsic loss and coupling states unambiguously. Furthermore, we achieve the direct measurement of collective phase dynamics and density of states of the Bloch modes in a synthetic frequency crystal, by in-situ OVA of a dynamically modulated microring resonator. Our in-situ OVA system provides a compact, high-precision, and broadband solution for characterizing future integrated photonic devices and circuits, with potential applications ranging from optical communications, biosensing, neuromorphic computing, to quantum information processing.