Euser Tijmen G, Harding Philip J, Vos Willem L
FOM Institute for Atomic and Molecular Physics (AMOLF), Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
Rev Sci Instrum. 2009 Jul;80(7):073104. doi: 10.1063/1.3156049.
We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21,050 cm(-1). A broad pump scan range allows a large optical penetration depth, while a broad probe scan range is crucial to study strongly photonic crystals. A new data acquisition method allows for sensitive pump-probe measurements, and corrects for fluctuations in probe intensity and pump stray light. We observe a tenfold improvement of the precision of the setup compared to laser fluctuations, allowing a measurement accuracy of better than DeltaR=0.07% in a 1 s measurement time. Demonstrations of the improved technique are presented for a bulk Si wafer, a three-dimensional Si inverse opal photonic bandgap crystal, and z-scan measurements of the two-photon absorption coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in the infrared wavelength range.
我们描述了一种用于研究纳米光子结构开关的超快时间分辨泵浦-探测光谱装置。飞秒泵浦脉冲和探测脉冲均可在3850至21,050 cm⁻¹的宽频率范围内独立调谐。宽泵浦扫描范围可实现较大的光穿透深度，而宽探测扫描范围对于研究强光子晶体至关重要。一种新的数据采集方法可实现灵敏的泵浦-探测测量，并校正探测强度波动和泵浦杂散光。我们观察到，与激光波动相比，该装置的精度提高了十倍，在1 s测量时间内测量精度优于ΔR = 0.07%。针对体硅晶片、三维硅反蛋白石光子带隙晶体以及在红外波长范围内对硅、砷化镓的双光子吸收系数和磷化镓的三光子吸收系数进行的z扫描测量，展示了该改进技术。
