Trägårdh Johanna, Gersen Henkjan
HH Wills Physics laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
Opt Express. 2013 Jul 15;21(14):16629-38. doi: 10.1364/OE.21.016629.
We show how a combination of near-field scanning optical microscopy with crossed beam spectral interferometry allows a local measurement of the spectral phase and amplitude of light propagating in photonic structures. The method only requires measurement at the single point of interest and at a reference point, to correct for the relative phase of the interferometer branches, to retrieve the dispersion properties of the sample. Furthermore, since the measurement is performed in the spectral domain, the spectral phase and amplitude could be retrieved from a single camera frame, here in 70 ms for a signal power of less than 100 pW limited by the dynamic range of the 8-bit camera. The method is substantially faster than most previous time-resolved NSOM methods that are based on time-domain interferometry, which also reduced problems with drift. We demonstrate how the method can be used to measure the refractive index and group velocity in a waveguide structure.
我们展示了近场扫描光学显微镜与交叉光束光谱干涉测量法相结合如何能够对光子结构中传播的光的光谱相位和幅度进行局部测量。该方法仅需要在感兴趣的单点和参考点进行测量，以校正干涉仪分支的相对相位，从而获取样品的色散特性。此外，由于测量是在光谱域中进行的，因此可以从单个相机帧中获取光谱相位和幅度，在此，对于信号功率小于100 pW的情况，受8位相机动态范围限制，可在70毫秒内完成。该方法比大多数以前基于时域干涉测量法的时间分辨近场扫描光学显微镜方法要快得多，这也减少了漂移问题。我们展示了该方法如何用于测量波导结构中的折射率和群速度。
