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Selective Anti-Stokes Excitation of a Single Defect Center in Hexagonal Boron Nitride
ACS Photonics ( IF 6.5 ) Pub Date : 2024-09-05 , DOI: 10.1021/acsphotonics.4c00594
Yudai Okashiro 1 , Hideaki Takashima 2 , Konosuke Shimazaki 1 , Kazuki Suzuki 1 , Yu Mukai 1 , Igor Aharonovich 3, 4 , Shigeki Takeuchi 1
Affiliation  

Hexagonal boron nitride (hBN) with defect centers is attracting attention as a promising candidate for single-photon emitters because its emission spectrum shows sharp emission peaks and it exhibits ultrabright single-photon emission at room temperature. However, when hBN containing multiple defect centers with various transition frequencies is excited using a pump laser with a wavelength shorter than the emission wavelength of the target defect center, problems such as a broad emission spectrum and nonsingle photon emission often arise. In this paper, we present a method for selectively exciting a single defect center in hBN nanoflakes by anti-Stokes excitation, where the wavelength of the excitation laser is longer than the emission wavelength of the target defect center. By exciting an hBN nanoflake with multiple defect centers using a 637 nm laser, as opposed to the normal excitation using a 532 nm laser, we observed a sharp emission peak and an antibunching dip (g2(0) = 0.08 ± 0.05) in the second-order correlation function, indicating strong evidence of a single defect center. In addition, we explored the temperature dependence of the emission spectrum from the defect centers in a hBN nanoflake to clarify the mechanism of the anti-Stokes excitation. As a result, we confirmed that single-phonon-mediated anti-Stokes excitation plays a substantial role in suppressing shorter-wavelength emissions and improving g2(0). Because this method uses a long-wavelength laser for excitation, it is speculated to substantially reduce the background photons generated not only inside the hBN nanoflakes but also in the optical fiber guiding the pump light, which is often a severe problem.

中文翻译:


六方氮化硼单缺陷中心的选择性反斯托克斯激发



具有缺陷中心的六方氮化硼(hBN)作为单光子发射器的有前途的候选者而引起人们的关注,因为它的发射光谱显示出尖锐的发射峰,并且在室温下表现出超亮的单光子发射。然而,当使用波长短于目标缺陷中心的发射波长的泵浦激光器来激发包含具有不同跃迁频率的多个缺陷中心的hBN时,经常会出现宽发射光谱和非单光子发射等问题。在本文中,我们提出了一种通过反斯托克斯激发选择性激发六方氮化硼纳米片中单个缺陷中心的方法,其中激发激光的波长比目标缺陷中心的发射波长长。通过使用 637 nm 激光激发具有多个缺陷中心的六方氮化硼纳米片(与使用 532 nm 激光的正常激发相反),我们在二阶相关函数,表明存在单个缺陷中心的有力证据。此外,我们还探讨了六方氮化硼纳米片缺陷中心发射光谱的温度依赖性,以阐明反斯托克斯激发的机制。结果,我们证实单声子介导的反斯托克斯激发在抑制较短波长发射和提高 g 2 (0) 方面发挥着重要作用。由于该方法使用长波长激光进行激发,因此推测不仅可以大幅减少六方氮化硼纳米片内部产生的背景光子,还可以大大减少引导泵浦光的光纤中产生的背景光子,这通常是一个严重的问题。
更新日期:2024-09-05
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