Lugt A V
Appl Opt. 1981 Aug 15;20(16):2770-9. doi: 10.1364/AO.20.002770.
Dynamic range is a key performance parameter for spectrum analyzers. The dynamic range of a Bragg cell power spectrum analyzer is generally limited by the dynamic range of self-scanned photodetector arrays. Interferometric techniques can be used to increase the dynamic range; but it is at the expense of increasing the number of photodetectors required, when the interference is introduced in the spatial domain, or a large photodetector bandwidth, when the interference is introduced in the temporal domain. In this paper we describe an interferometric approach wherein a second Bragg cell generates a spatially modulated reference waveform to produce an interference term that has a constant temporal frequency for all spatial frequencies. The advantages of this approach are lower photodetector bandwidth, improved dynamic range, improved cross talk suppression, more efficient use of the Bragg cell time-bandwidth product, immunity to scattered noise, and improved short pulse detectability. The chief disadvantage is the need for a discrete element photodetector array; when such arrays become available in hybrid or integrated packages, an additional advantage will be that of parallel postdetection processing.
动态范围是频谱分析仪的一个关键性能参数。布拉格单元功率谱分析仪的动态范围通常受限于自扫描光电探测器阵列的动态范围。干涉测量技术可用于增加动态范围；但代价是，当在空间域引入干涉时，所需光电探测器的数量会增加，或者当在时间域引入干涉时，光电探测器带宽会增大。在本文中，我们描述了一种干涉测量方法，其中第二个布拉格单元生成一个空间调制的参考波形，以产生一个对于所有空间频率都具有恒定时间频率的干涉项。这种方法的优点包括较低的光电探测器带宽、改善的动态范围、更好的串扰抑制、更有效地利用布拉格单元的时间 - 带宽积、对散射噪声的免疫以及更好的短脉冲可探测性。主要缺点是需要一个离散元件光电探测器阵列；当这种阵列以混合或集成封装形式可用时，另一个优点将是并行检测后处理。
