研究目的
Investigating the nonlinear optical response in As50S50 thin films under nanosecond near resonant excitation and its application as an optical limiter for optoelectronic sensors.
研究成果
The As50S50 thin films exhibit strong nonlinear optical response under nanosecond near resonant excitation, with the nonlinear absorption coefficient and nonlinear refractive index being the highest reported in amorphous semiconductors. The observed effects are explained by a three-level energy band model, indicating reverse saturable absorption mediated by excited-state absorption. The films show potential for application as optical limiters for optoelectronic sensors.
研究不足
The study is limited to the nonlinear optical response under nanosecond near resonant excitation. The potential thermal effects and photo damage under continuous or higher intensity laser exposure were not explored.
1：Experimental Design and Method Selection:
The study employed the Z-scan technique to measure the nonlinear optical response of As50S50 thin films under nanosecond near resonant excitation. A three-level energy band model was proposed to explain the observed effects.
2：Sample Selection and Data Sources:
As50S50 thin films were prepared using the melt-quenching method and thermal evaporation technique. The films' composition and amorphous nature were confirmed through energy-dispersive x-ray analysis and x-ray diffraction measurements.
3：List of Experimental Equipment and Materials:
A Horiba JY LabRam HR Evolution Spectrometer for Raman spectroscopy, a Nd:YAG laser for Z-scan measurements, and a Xenon Arc lamp for pump-probe transient absorption measurements were used.
4：Experimental Procedures and Operational Workflow:
The Z-scan technique was used in both open-aperture and closed-aperture configurations to determine the nonlinear absorption coefficient and nonlinear refractive index, respectively. Nanosecond pump-probe measurements were conducted to study the interband relaxation time.
5：Data Analysis Methods:
The nonlinear optical parameters were extracted by fitting the experimental data with theoretical models. The interband relaxation time was determined from transient absorption kinetics.
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