Ultra-simplified diffraction-based computational spectrometer

We have developed an ultra-simplified compact computational spectrometer that achieves a reconstructed spectrum accuracy better than 1 nm over a bandwidth of 200 nm and a spectral peak resolution of 3 nm, all within a compact footprint under half an inch.
Published in Physics
Ultra-simplified diffraction-based computational spectrometer
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Miniaturizing spectrometers for mobile platforms has been a significant challenge in spectroscopy research. Previous designs often relied on intricate dispersion, high-precision fabrication, and complex calibration. Recently, we have demonstrated a compact spectrometer design with ultra-simplified architecture, offering a comprehensive alternative to current state-of-the-art compact computational spectrometers [1].

Inspired by the mono coherent diffractive imaging (CDI) approach introduced by Huijts et. al in 2020 [2], we propose a novel one-to-broadband diffraction decomposition strategy in computational spectrometer, facilitated by a numerical regularized transform using a spectral-point-spread-function (PSF) derived exclusively from the spectrumof the diffracted radiation. Our design introduces a conceptual leap in coherent mode decomposition with a PSF, rendering the architecture ultra-simplified and cost-effective. By employing a numerical regularized transform based on a single-shot measurement of quasi-monochromatic diffraction as the PSF, we eliminate the need for complex spectral encoding and calibrations. This streamlined design offers versatility for miniaturized, cost-effective, and lab-on-chip integrations.

A primary achievement of our method lies in its unprecedented compatibility, delivering wide bandwidth and precise spectral measurements. Our spectrometer achieves a reconstructed spectral peak precision of less than 1 nm over a 200 nm bandwidth, coupled with remarkable resolution for peaks within 3 nm separation. This level of performance is achieved from a single shot of a broadband diffraction pattern, bypassing the need for intricate dispersion designs and meticulous fabrications.

Notably, our innovative approach incorporates an arbitrarily shaped pinhole as a diffraction-based partial-disperser, positioned in front of the detector. This eliminates the need for intricate pre-encoding designs, making the spectrometer ultra-simplified and highly cost-effective, with a core disperser device priced at nearly one dollar.

Authors: Chuangchuang Chen, Honggang Gu, Shiyuan Liu.

References

[1] C. Chen, H. Gu, and S. Liu, "Ultra-simplified diffraction-based computational spectrometer," Light Sci. Appl.  13, 9 (2024). https://doi.org/10.1038/s41377-023-01355-4

[2] J. Huijts, S. Fernandez, D. Gauthier, M. Kholodtsova, A. Maghraoui, K. Medjoubi, A. Somogyi, W. Boutu, and H. Merdji, "Broadband coherent diffractive imaging," Nat. Photonics 14, 618–622 (2020). https://doi.org/10.1038/s41566-020-0660-7

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