Institute of Electrical and Optical Communications Engineering (INT), University of Stuttgart, 70569 Stuttgart, Germany.
Institute of Interfacial Process Engineering and Plasma Technology (IGVP), University of Stuttgart, 70569 Stuttgart, Germany.
Biosensors (Basel). 2017 Sep 14;7(3):37. doi: 10.3390/bios7030037.
The dual-mode interferometer (DMI) is an attractive alternative to Mach-Zehnder interferometers for sensor purposes, achieving sensitivities to refractive index changes close to state-of-the-art. Modern designs on silicon-on-insulator (SOI) platforms offer thermally stable and compact devices with insertion losses of less than 1 dB and high extinction ratios. Compact arrays of multiple DMIs in parallel are easy to fabricate due to the simple structure of the DMI. In this work, the principle of operation of an integrated DMI with differential outputs is presented which allows the unambiguous phase shift detection with a single wavelength measurement, rather than using a wavelength sweep and evaluating the optical output power spectrum. Fluctuating optical input power or varying attenuation due to different analyte concentrations can be compensated by observing the sum of the optical powers at the differential outputs. DMIs with two differential single-mode outputs are fabricated in a 250 nm SOI platform, and corresponding measurements are shown to explain the principle of operation in detail. A comparison of DMIs with the conventional Mach-Zehnder interferometer using the same technology concludes this work.
双模干涉仪（DMI）是用于传感器的马赫-曾德尔干涉仪的一种有吸引力的替代方案，其对折射率变化的灵敏度接近最新水平。基于绝缘体上硅（SOI）平台的现代设计提供了热稳定且紧凑的器件，其插入损耗小于 1 dB，消光比高。由于 DMI 的结构简单，很容易在平行方向上制造出具有多个 DMI 的紧凑阵列。在这项工作中，提出了具有差分输出的集成 DMI 的工作原理，该原理允许通过单次波长测量进行明确的相移检测，而无需使用波长扫描并评估光学输出功率谱。通过观察差分输出处的光功率总和，可以补偿波动的光输入功率或由于不同分析物浓度引起的衰减。在 250nm SOI 平台上制造了具有两个差分单模输出的 DMI，并进行了相应的测量，以详细解释其工作原理。使用相同技术的 DMI 与传统的马赫-曾德尔干涉仪的比较结束了这项工作。
