Towards integrated sensors for optimized OCT with undetected photons

TL;DR

This paper presents an integrated sensor scheme for optical coherence tomography with undetected photons, demonstrating improved performance and high axial resolution using nonlinear waveguides and optimized measurement schemes.

Contribution

It introduces a novel integrated OCT sensor scheme with undetected photons, comparing SU(1,1) and induced coherence methods, and demonstrates high-resolution measurements.

Findings

Induced coherence scheme outperforms SU(1,1) in integrated systems.

Achieved axial resolution as low as 28 micrometers.

Optimized pump gain enhances measurement performance.

Abstract

The development of practical sensors for optical coherence tomography (OCT) with undetected photons requires miniaturization via integration. To be practical, these sensors must exhibit a large spectral bandwidth and a high brightness, which are linked to a high axial resolution and a sufficient signal to noise ratio, respectively. Here, we combine these requirements in a scheme for OCT-measurements with undetected photons based on nonlinear Ti:LiNbO$_3$ waveguides. We investigate the performance benchmarks of the commonly used SU(1,1) scheme in comparison to an induced coherence scheme and find that the latter is actually better suited when implementing measurements with undetected photons in integrated systems. In both schemes, we perform pump gain optimization and OCT measurements with undetected photons with an axial resolution as low as 28 $\mathrm{\mu}$m.