Spatial multiplexing of whispering gallery mode sensors for trace species detection

Holler, Stephen; Speck, Matthew

doi:10.1117/12.2223340

Cited by 2 publications

(3 citation statements)

References 16 publications

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“…In some other free-space coupling studies, the scattered resonant light was measured with a CCD or CMOS image sensor 32,50,51 , which is limited by the resolution, dynamic range, and frame rate. Our use of a DMD combined with a high-performance single-pixel detector here provides better resolution, controllable gain, and a fast response, while maintaining the capability for spatial imaging.…”

Section: Resonance Line Shapes and System Efficiencymentioning

confidence: 99%

“…This optical configuration is also compatible with other WGM resonators since they rely on the same principle. For example, monitoring microsphere resonances through scattering has been reported 32,33 . An analytic expression for the free space coupling efficiency to WGM resonators exists 34 , suggesting that maximum coupling efficiency can be enhanced by reducing the size of the Gaussian beam waist.…”

Section: Introductionmentioning

confidence: 99%

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Ultra-high-Q free-space coupling to microtoroid resonators

Suebka,

McLeod,

2024

Light Sci Appl

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Whispering gallery mode (WGM) microtoroid resonators are one of the most sensitive biochemical sensors in existence, capable of detecting single molecules. The main barrier for translating these devices out of the laboratory is that light is evanescently coupled into these devices though a tapered optical fiber. This hinders translation of these devices as the taper is fragile, suffers from mechanical vibration, and requires precise positioning. Here, we eliminate the need for an optical fiber by coupling light into and out from a toroid via free-space coupling and monitoring the scattered resonant light. A single long working distance objective lens combined with a digital micromirror device (DMD) was used for light injection, scattered light collection, and imaging. We obtain Q-factors as high as $$1.6\times {10}^{8}$$ 1.6 × 10 8 with this approach. Electromagnetically induced transparency (EIT)-like and Fano resonances were observed in a single cavity due to indirect coupling in free space. This enables improved sensing sensitivity. The large effective coupling area (~10 μm in diameter for numerical aperture = 0.14) removes the need for precise positioning. Sensing performance was verified by combining the system with the frequency locked whispering evanescent resonator (FLOWER) approach to perform temperature sensing experiments. A thermal nonlinear optical effect was examined by tracking the resonance through FLOWER while adjusting the input power. We believe that this work will be a foundation for expanding the implementation of WGM microtoroid resonators to real-world applications.

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Section: Resonance Line Shapes and System Efficiencymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultra-high-Q free-space coupling to microtoroid resonators

Suebka,

McLeod,

2024

Light Sci Appl

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“…One way to circumvent the limitations of serial coupling is to switch coupling schemes and implement an imaging stage using low-cost CCD detectors for parallel, spatially multiplexed detection [4]. In what follows, we will discuss this approach and demonstrate its ability to obtain resonance spectra from optical microcavities.…”

Section: Introductionmentioning

confidence: 99%

Spatial Multiplexing of Whispering Gallery Mode Sensors

Holler

Speck

2023

Sensors

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Whispering gallery mode resonators have proven to be robust and sensitive platforms for the trace detection of chemical and/or biological analytes. Conventional approaches using serially addressed resonators face challenges in simultaneous multi-channel (i.e., multi-species) detection. We present an alternative monitoring scheme that allows for the spatial multiplexing of whispering gallery mode resonators with the simultaneous observation of the resonance spectra from each of them. By imaging arrays of microspheres and monitoring the glare spot intensities through image processing routines, resonance spectra from multiple resonators may be simultaneously recorded without interference or confounding effects of serial excitation/detection. We demonstrate our multiplexed imaging approach with bulk refractive index variations and virus–antibody binding.

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Spatial multiplexing of whispering gallery mode sensors for trace species detection

Cited by 2 publications

References 16 publications

Ultra-high-Q free-space coupling to microtoroid resonators

Ultra-high-Q free-space coupling to microtoroid resonators

Spatial Multiplexing of Whispering Gallery Mode Sensors

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