In-situ Optical Vector Analysis Based on Integrated Lithium Niobate Single-Sideband Modulators

Optical vector analysis (OVA) is an enabling technology for comprehensivelycharacterizing both amplitude and phase responses of optical devices orsystems. Conventional OVA technologies are mostly based on discreteoptoelectronic components, leading to unsatisfactory system sizes, complexity,and stability. They also encounter challenges in revealing the on-chipcharacteristics of integrated photonic devices, which are often overwhelmed bythe substantial coupling loss and extra spectral response at chip facets. Inthis work, we demonstrate a miniaturized OVA system for integrated photonicsdevices based on broadband single sideband (SSB) modulators on a thin-filmlithium niobate (LN) platform. The OVA could provide a direct probe of bothamplitude and phase responses of photonic devices with kHz-level resolution andtens of terahertz measurement bandwidth. We perform in-situ characterizationsof single and coupled microring resonators fabricated on the same chip as theOVA, unfolding their intrinsic loss and coupling states unambiguously.Furthermore, we achieve the direct measurement of collective phase dynamics anddensity of states of the Bloch modes in a synthetic frequency crystal, byin-situ OVA of a dynamically modulated microring resonator. Our in-situ OVAsystem provides a compact, high-precision, and broadband solution forcharacterizing future integrated photonic devices and circuits, with potentialapplications ranging from optical communications, biosensing, neuromorphiccomputing, to quantum information processing.