Optimized design of the lithium niobate for spectrally-pure-state generation at MIR wavelengths using metaheuristic algorithm

TL;DR

This paper demonstrates an optimized lithium niobate crystal design using a metaheuristic algorithm to generate spectrally pure quantum states in the mid-infrared range, enhancing spectral purity and tunability.

Contribution

It introduces a novel optimization approach for lithium niobate crystals to improve MIR quantum light sources, achieving near-perfect spectral purity and broad wavelength tunability.

Findings

Spectral purity improved from 0.820 to 0.998

Wavelength tunability from 3.0 to 4.0 μm (degenerate)

Wavelength tunability from 3.0 to 3.7 μm (nondegenerate)

Abstract

Quantum light sources in the mid-infrared (MIR) band play an important role in many applications, such as quantum sensing, quantum imaging, and quantum communication. However, there is still a lack of high-quality quantum light sources in the MIR band, such as the spectrally pure single-photon source. In this work, we present the generation of spectrally-pure state in an optimized poled lithium niobate crystal using a metaheuristic algorithm. In particular, we adopt the particle swarm optimization algorithm to optimize the duty cycle of the poling period of the lithium niobate crystal. With our approach, the spectral purity can be improved from 0.820 to 0.998 under the third group-velocity-matched condition, and the wavelength-tunable range is from 3.0 $\mu$m to 4.0 $\mu$m for the degenerate case and 3.0 $\mu$m to 3.7 $\mu$m for the nondegenerate case. Our work paves the way for developing quantum photonic technologies at the MIR wavelength band.