Dual-Polarization Bandwidth-Bridged Bandpass Sampling Fourier Transform Spectrometer from Visible to Near-Infrared on a Silicon Nitride Platform

Yoo, Kyo Sang; Chen, Ray T.

doi:10.1021/acsphotonics.2c00451

Cited by 9 publications

(8 citation statements)

References 43 publications

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“…Also, the FSR broadening of nanobeam cavities is typically accompanied by the tightly confined mode volume, resulting in a narrow tuning range and an increase in aggregate power consumption. , For FTSs, the unknown spectrum is retrieved in the Fourier domain from a modulated interferogram. Various schemes, e.g., spatial heterodyne Mach–Zehnder interferometers (MZIs), − tunable/switchable MZIs, − and stationary-wave interferometers, − have been reported to implement the chip-scale Fourier spectrometry. The major shortcoming of integrated FTSs is the centimeter-scale device footprint, as the resolution is inversely proportional to the optical path length (OPL) or maximum power applied, and the broad bandwidth relies on a massive number of spatial channels or complex switch topologies.…”

Section: Introductionmentioning

confidence: 99%

Integrated Single-Resonator Spectrometer beyond the Free-Spectral-Range Limit

Qin

et al. 2023

ACS Photonics

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The chip-scale miniaturization of optical spectrometers may enable many potential applications, such as wearable health monitoring, field deployable biochemical sensing, dense hyperspectral imaging, and portable optical coherence tomography. However, the widespread use of integrated spectrometers is hampered by an inherent trade-off between resolutions and bandwidths. Here, a ground-breaking design strategy is proposed to overcome the bottleneck. The most noteworthy finding in this work is that, by simultaneously leveraging temporal and spatial decorrelations, a single micro-ring resonator (MRR) can serve as a spectrometer with an ultra-high-resolution across an ultrabroad bandwidth far exceeding the narrow free spectral range (FSR). The structure is based on a tunable MRR that supports TE 0 and TE 1 transverse modes. When tuning the MRR, the unknown spectrum is scanned by dual-mode resonances in a synchronized manner. The recorded signal is formed by "splicing" the responses of TE 0 and TE 1 . Due to the intermodal dispersion, all of the wavelength channels in the transmission matrix are sufficiently decorrelated beyond the FSR limit by cross-referring two matrix halves; thus, any arbitrary spectra can be retrieved by solving a linear inverse problem with preconditioned iterative optimizations. Experimental results demonstrate an ultrahigh resolution of <80 pm across an ultrabroad working bandwidth of >100 nm, which yields an ultralarge-wavelength channel capacity of 1250. The device footprint is also as compact as 20 × 35 μm 2 . These results represent the smallest-resolution-footprint product (≈0.056 pm•mm 2 ), the highest bandwidth-to-footprint ratio (≈0.14 nm μm −2 ), and the highest channel-to-footprint ratio (≈1.79 μm −2 ) ever demonstrated.

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Section: Introductionmentioning

confidence: 99%

Integrated Single-Resonator Spectrometer beyond the Free-Spectral-Range Limit

Qin

et al. 2023

ACS Photonics

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“…The input/output fibers were not relocated during the measurement of each port, ensuring an accurate mapping between A and O . This proof-of-concept method has been used in prior works on SHSs 23 and speckle spectrometers 49 . Practical multiport acquisition can be realized by integrating silicon-germanium PDs to each output channel and reading their signals under a synchronized clock 50 .…”

Section: Methodsmentioning

confidence: 99%

Scalable integrated two-dimensional Fourier-transform spectrometry

Xu,

Qin,

et al. 2024

Nat Commun

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Integrated spectrometers offer the advantages of small sizes and high portability, enabling new applications in industrial development and scientific research. Integrated Fourier-transform spectrometers (FTS) have the potential to realize a high signal-to-noise ratio but typically have a trade-off between the resolution and bandwidth. Here, we propose and demonstrate the concept of the two-dimensional FTS (2D-FTS) to circumvent the trade-off and improve scalability. The core idea is to utilize 2D Fourier transform instead of 1D Fourier transform to rebuild spectra. By combining a tunable FTS and a spatial heterodyne spectrometer, the interferogram becomes a 2D pattern with variations of heating power and arm lengths. All wavelengths are mapped to a cluster of spots in the 2D Fourier map beyond the free-spectral-range limit. At the Rayleigh criterion, the demonstrated resolution is 250 pm over a 200-nm bandwidth. The resolution can be enhanced to 125 pm using the computational method.

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“…According to bandpass sampling theory, the interferogram from post-dispersed FTS has the characteristics of a small number of sampling points and a large sampling interval along the optical path difference. Due to its attractive advantages, BPS-FTS has been widely studied and different types of BPS-FTS have been proposed [7][8][9][10][11][12][13][14][15]. Compared to post-dispersed FTS, BPS-FTS has many theoretical issues and technical challenges that still need to be analyzed and addressed, which arise from bandpass sampling and limit the implementation of BPS-FTS.…”

Section: Introductionmentioning

confidence: 99%

Suitable Integral Sampling for Bandpass-Sampling Time-Modulated Fourier Transform Spectroscopy

Chen,

Tan,

Zhao

et al. 2024

Applied Sciences

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For traditional Fourier transform (FTS), its integral sampling usually meets the Spectral Modulation Transfer Function (SMTF) criterion. However, for bandpass-sampling Fourier transform spectroscopy (BPS-FTS), based on our analysis, the integral sampling condition derived from the Spectral Modulation Transfer Function (SMTF) is excessively stringent. In other words, the interval of the integral sampling time that fulfills the tolerance requirements for the reconstructed spectrum is very narrow. There are numerous integration sampling time intervals outside this range that still meet the tolerance requirements for the reconstructed spectrum. In this paper, through theoretical modeling, we propose a method based on average |SMTF| as the selection criterion for the integration sampling time. Through simulation analysis, it is evident that the intervals and range of the integral sampling time obtained via this method are more accurate, ensuring the tolerance requirements of the reconstructed spectrum. Under these intervals, when conducting integral sampling on the interferogram, the spectral deviation of the reconstructed spectrum is minimal, and the Spectral Correlation Mapper (SCM) is nearly equal to one. This indicates that compared with the SMTF criterion in traditional FTS, this method is more suitable for the characteristics of BPS-FTS. The analysis in this paper can provide theoretical and simulation support for the implementation of BPS-FTS.

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Dual-Polarization Bandwidth-Bridged Bandpass Sampling Fourier Transform Spectrometer from Visible to Near-Infrared on a Silicon Nitride Platform

Cited by 9 publications

References 43 publications

Integrated Single-Resonator Spectrometer beyond the Free-Spectral-Range Limit

Integrated Single-Resonator Spectrometer beyond the Free-Spectral-Range Limit

Scalable integrated two-dimensional Fourier-transform spectrometry

Suitable Integral Sampling for Bandpass-Sampling Time-Modulated Fourier Transform Spectroscopy

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