Adaptive etalon suppression technique for long‐term stability improvement in high index contrast waveguide‐based laser absorption spectrometers. Issue 15 (1st July 2019)

• Record Type: Journal Article
• Authors: Zhang, E.J.; Tombez, L.; Teng, C.C.; Wysocki, G.; Green, W.M.J.
• Is Part Of: Electronics letters. Volume 55:Issue 15(2019)
• Page Start: 851
• Page End: 853
• Publication Date: 2019-07-01
• Subjects: infrared spectra -- silicon -- regression analysis -- measurement by laser beam -- optical waveguides -- elemental semiconductors -- laser noise -- chemical sensors -- organic compounds -- optical sensors -- infrared detectors -- photodetectors -- light interferometry -- light interference -- adaptive optics -- light reflection -- statistical analysis; line‐scanned optical absorption spectrometers -- etalon spectral background -- spectral baseline recalibration interval -- near‐infrared methane absorption spectroscopy -- stochastic line‐edge roughness imperfections -- Gaussian‐noise limited performance -- on‐chip sensor embodiment -- absorption sensor -- adaptive etalon suppression technique -- long‐term stability improvement -- high index contrast waveguide‐based laser absorption spectrometers -- nonlinear regression model -- light reflections -- time‐varying etalon drifts -- on‐chip silicon waveguide -- dynamic etalon fitting‐routine -- fringe subtraction models -- Allan‐variance analysis -- size 10.0 cm -- Si; Electronics -- Periodicals; 621.381
• DOI: 10.1049/el.2019.0901
• Languages: English
• ISSNs: 0013-5194

Abstract

Abstract : The authors present an adaptive algorithm based on a non‐linear regression model for mitigating time‐varying etalon drifts in line‐scanned optical absorption spectrometers. By dynamically varying the etalon spectral background using physically realistic degrees of freedom, the authors' dynamic etalon fitting‐routine (DEF‐R) significantly increases the spectral baseline recalibration interval as compared to conventional fringe subtraction models. They provide an empirical demonstration of the efficacy of DEF‐R using an on‐chip 10 cm silicon waveguide for near‐infrared methane absorption spectroscopy at 6057 cm −1, which suffers significant etalon spectral noise due to reflections and multi‐path interference from stochastic line‐edge roughness imperfections. They demonstrate the corresponding improvement in both spectral clean‐up and long‐term stability via Allan‐variance analysis. For the sensor presented here, application of DEF‐R enables Gaussian‐noise limited performance for more than 10 2 s and provides almost an order‐of‐magnitude improvement in stability time with respect to conventional baseline subtraction. Although DEF‐R is applied here to an on‐chip sensor embodiment, they envision their technique to be applicable to any absorption sensor limited by time‐varying etalon drifts.