Athermal planar-waveguide Fourier-transform spectrometer for methane detection

Abstract

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous. Abstract:We demonstrate a passively thermally-stabilized planar waveguide Fourier-transform spectrometer for remote detection of atmospheric methane. The device is implemented as a spatial heterodyne spectrometer using an array of 100 Mach-Zehnder interferometers (MZIs) on an integrated photonic chip. The spectrometer is buffered against temperature fluctuations by using waveguides with a carefully engineered, athermal geometry. The achieved waveguide thermooptic optic coefficient is 3.5 × 10 −6 K −1 . Effective entrance aperture is increased over dispersive element spectrometers, without sacrificing spectral resolution, by coupling light independently to each of the 100 MZIs. The output of each MZI is sampled in quadrature, to compensate for non-uniform illumination across the MZI input apertures. The spectrometer is validated using a methane reference cell in a benchtop setup: an interferogram is inverted via least-squares spectral analysis (LSSA) to retrieve multiple absorption lines at a spectral resolution of 50 pm over a 1 nm free spectral range (FSR) centered at λ 0 = 1666.5 nm. The retrieved spectrum is compared against the Beer-Lambert absorption law and is found to provide a correct measurement of the volume mixing ratio (VMR) in the optical path. 44(10), 761-765 (1954 Florjańczyk, and M. Vachon, "High-resolution Fourier-transform spectrometer chip with microphotonic silicon spiral waveguides," Opt. Lett., 38(5), 706-708 (2013). 13. M. Yang, M. Li, and J.-J. He, "Static FT imaging spectrometer based on a modified waveguide MZI array," Opt.

Research Progress on On‐Chip Fourier Transform Spectrometer

“…The third challenge yet to be addressed in the implementation of SHSs based on MZI arrays lies in compensation for rapid thermal drifts, which result in nonuniform sampling of the interferogram. [83] Temperature changes lead to changes in the refractive index of the waveguide, which further lead to changes in the OPD. Takada et al provided thermal control and temperature stability to a spectrometer by placing temperature controllers on both sides of the waveguide, allowing it to operate without recalibration.…”

“…Inset: magnified view of the spiral structure [73]. b) Photograph of an FTS chip next to a 25-cent Canadian coin [83]. c) MZI-based modulators [137].…”

“…Copyright 2013, Optical Society of America. b) Reproduced with permission [83]. Copyright 2017, Optical Society of America.…”

On-chip spectrometer : design, fabrication and experiment

“…The optical spectrometer has been made smaller and smaller for more convenience and lower cost [2][3][4][5] as it is critical to bring the chemical/biological sensing, spectroscopy, and spectral imaging into robust, compact 3 and cost-effective devices. Hence, on-chip spectrometer has been a hot research topic with the development of devices requiring spectrum analysis such as wavelength monitoring [6][7][8], photonic sensors and on-chip spectroscopy [9][10][11][12][13][14][15][16] The maturity of nano-silicon-photonic fabrication technology and availability of foundries has enabled the integration of large scale photonic devices on a single chip [17]. And actually, the nano-silicon-photonic fabrication line has been perfectly applied in integrated photonic devices fabrication.…”

“…Conventional Fourier-transform (FT) spectrometer using Michelson interferometer is known for high resolution, broadband and high SNR, which is suitable for infrared (IR) applications [32]. On-chip FT spectrometers are also demonstrated such as FT spectrometer based on micro-electromechanical systems (MEMS) technology [33][34][35][36], stationary-wave integrated FT spectrometer (SWIFT) [37,38], spatial heterodyne spectrometers (SHS) [16,[39][40][41][42][43][44], thermally tunable MZI [45,46], co-propagative FT (CPFT) spectrometer [47] and digital Fourier-transform (DFT) spectrometer [48,49]. The similar trade-off between channel count and SNR is encountered in most FT methods.…”