光致发光
限制
吸收(声学)
材料科学
非线性光学
非线性光学
凝聚态物理
非线性系统
Crystal(编程语言)
光学
化学物理
分子物理学
光电子学
物理
量子力学
复合材料
计算机科学
机械工程
工程类
程序设计语言
作者
Anıl Doğan,Ahmet Karatay,M. Isik,Elif Akhüseyin Yıldız,Nizami Gasanly,Ayhan Elmalı
标识
DOI:10.1088/1402-4896/ad3aee
摘要
Abstract Nonlinear absorption properties of PbMo0.75W0.25O4 single crystal fabricated by the Czochralski method were studied. The band gap energy of the crystal was determined as 3.12 eV. Urbach energy which represents the defect states inside the band gap was found to be 0.106 eV. PbMo0.75W0.25O4 single crystal has a broad photoluminescence emission band between 376 and 700 nm, with the highest emission intensity occurring at 486 nm and the lowest intensity peak at 547 nm, depending on the defect states. Femtosecond transient absorption measurements reveal that the lifetime of localized defect states is found to be higher than the 4 ns pulse duration. Open aperture (OA) Z-scan results demonstrate that the PbMo0.75W0.25O4 crystal exhibits nonlinear absorption (NA) that includes simultaneous two-photon absorption (TPA) as the dominant mechanism at the 532 nm excitations corresponding to 2.32 eV energy. NA coefficient (βeff) increased from 7.24 x 10-10 m/W to 8.81 x 10-10 m/W with increasing pump intensity. At higher intensities βeff tends to decrease with intensity increase. This decrease is an indication that saturable absorption (SA) occurred along with the TPA, called saturation of TPA. The lifetime of the defect states was measured by femtosecond transient absorption spectroscopy. Saturable absorption behavior was observed due to the long lifetime of the localized defect states. Closed aperture (CA) Z-scan trace shows the sign of a nonlinear refractive index. The optical limiting threshold of PbMo0.75W0.25O4 single crystal at the lowest intensity was determined as 3.45 mJ/cm2. Results show that the PbMo0.75W0.25O4 single crystal can be a suitable semiconductor material for optical limiting applications in the visible region.
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