2025/01/24 by Wu‐Hao Cai, So-Young Baek, Cai, Wu-Hao +5
Engineering · Medicine · Physics and Astronomy · #Advanced Optical Sensing Technologies #FOS: Physical sciences #Ocular and Laser Science Research #Photonic and Optical Devices #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.2501.14214
openalex publication_date 2025/01/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We report on optimizing the spectral purity of heralded single photons in the telecom O-band, where single photons can be propagated with low loss and low dispersion in a standard telecom optical fiber. We numerically searched for various group-velocity-matching conditions and corresponding optimal poling structures of a potassium titanyl phosphate crystal for spontaneous parametric downconversion. Our poling optimization results using phase-matching coherence-length and sub-coherence-length modulation schemes show > 99.4% spectral purity with pump wavelengths ranging from 603.8 nm to 887.3 nm. Some optimized configurations are feasible with off-the-shelf lasers and single-photon detectors. Moreover, by investigating noise photon spectra for different poling optimization methods, we show that, in practice, appropriate, gentle spectral filtering helps achieve high purity. This study will pave the way for developing practical quantum sources for quantum information applications at the telecom O-band.