Figure 1. LSTM-enabled interferometric sensing system with high sensitivity and wide measurement range. (IMAGE)
Caption
Figure 1. LSTM-enabled interferometric sensing system with high sensitivity and wide measurement range. a. Sensing system mainly consists of a broadband light source, single-mode fiber (prepared based on the flame-based conical mechanism), and a spectral analyzer. Meanwhile, a schematic diagram of the internal sensing optical path is also shown in the figure. b. Dynamic spectral response and sensing mechanism. Conventional methods are limited to tracking spectral shifts within a single FSR. Changes in the refractive index (RI) across multiple FSRs introduce ambiguity in spectral response analysis. Specifically, within one FSR range, as RI changes, a new Dip D appears between Dip A and Dip B, and the spectrum overlaps with Dip C at the same wavelength, but they correspond to different measured values. This phenomenon persists across the entire measurement range, underscoring the need for intelligent spectral analysis. c. Intelligent data processing and feature learning process. To accurately decode complex spectral variations and map them directly to the value of RI, the system employs a LSTM network for end-to-end data processing. The network's memory cells can selectively retain spectral features relevant to the RI via the coordinated action of the input, forget, and output gates, thereby governing the update and output of the hidden state. d. Model performance and error analysis. The fully trained LSTM model exhibits extremely high prediction accuracy. The refractive index values predicted by the model are highly consistent with the actual measured values. This proves that the intelligent sensing system not only achieves high-precision refractive index measurement but also has excellent stability and reliability, providing a powerful solution for optical sensing in complex environments.
Credit
Junling Hu et al.
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CC BY