Interference fringes in a nonlinear Michelson interferometer based on spontaneous parametric down-conversion

TL;DR

This paper presents a systematic study of a quantum nonlinear Michelson interferometer based on spontaneous parametric down-conversion, demonstrating theoretical and experimental results for interference phenomena and applications in measuring crystal properties.

Contribution

It introduces a simplified theoretical model of the QNI and experimentally verifies interference effects, applying it to measure refractive index and surface angles of a BBO crystal.

Findings

Interference visibility and coherence length are demonstrated both theoretically and experimentally.

Equal-inclination and equal-thickness interference effects are characterized.

The QNI effectively measures crystal refractive index and surface angles.

Abstract

Quantum nonlinear interferometers (QNIs) can measure the infrared physical quantities of a sample by detecting visible photons. A QNI with Michelson geometry based on the spontaneous parametric down-conversion in a second-order nonlinear crystal is studied systematically. A simplified theoretical model of the QNI is presented. The interference visibility, coherence length, equal-inclination interference, and equal-thickness interference for the QNI are demonstrated theoretically and experimentally. As an application example of the QNI, the refractive index and the angle between two surfaces of a BBO crystal are measured using equal-inclination interference and equal-thickness interference.