Single-particle photothermal imaging via inverted excitation through high-Q all-glass toroidal microresonators

Knapper, Kassandra A.; Pan, Feng; Rea, Morgan T.; Horak, Erik H.; Rogers, Jeremy D.; Goldsmith, Randall H.

doi:10.1364/oe.26.025020

Cited by 22 publications

(18 citation statements)

References 52 publications

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“…13 High backgrounds in SiO2-Si toroids can be mitigated with all-glass microtoroids, which can be used for visible spectroscopy. 15,16 However, immersing a WGM microresonator in water mandates the use of larger microresonators to avoid bending losses, 65 with consequent lower photothermal sensitivity. Furthermore, although tapers 66 and prisms 9 can be optically coupled to WGM microresonators in water, immersion of such couplers in solution may reduce mechanical stability and also result in fouling, particularly as more caustic reagents are employed for chemical studies.…”

Section: Toward Real-time Monitoring and Control Of Single Nanoparticle Properties With A Microbubble Resonator Spectrometermentioning

confidence: 99%

“…12 However, the ability to perform spectroscopy on adsorbed objects would not only open a path toward label-free chemical identification, but also allow the interrogation of single object properties, free from the static and dynamic blurring of typical ensemble measurements. To this end, we recently employed microtoroid resonators as single-particle absorption spectrometers, whereby the heat dissipated by optically pumped nano-objects such as gold nanorods (AuNRs), [13][14][15][16] carbon nanotubes, 17 or conductive polymers 18 is detected via small shifts in the WGM resonance condition. However, to harness the sensitivity of this method for chemically dynamic systems, a platform easily compatible with solution-phase measurements is necessary.…”

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confidence: 99%

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Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer

Hogan¹,

Horak²,

Ward³

et al. 2019

Preprint

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Optical microresonators have widespread application at the frontiers of nanophotonic technology, driven by their ability to confine light to the nanoscale and enhance light-matter interactions. Microresonators form the heart of a new method for single-particle photothermal absorption spectroscopy, whereby the microresonators act as microscale thermometers to detect the heat dissipated by optically pumped, non-luminescent nanoscopic targets. However, translation of this technology to chemically dynamic systems requires a platform that is mechanically stable, solution compatible, and visibly transparent. We report microbubble absorption spectrometers as a new and versatile platform that meets these requirements. Microbubbles integrate a two-port microfluidic device within a Whispering Gallery Mode (WGM) microresonator, allowing for the facile exchange of chemical reagents within the resonator’s interior while maintaining a solution-free environment on its exterior. We first leverage these qualities to investigate the photo-activated etching of single gold nanorods by ferric chloride, providing a new method for rapid acquisition of spatial and morphological information about nanoparticles as they undergo chemical reactions. We then demonstrate the ability to control nanorod orientation within a microbubble through optically exerted torque, a new route toward the construction of hybrid photonic-plasmonic systems. Critically, the reported platform advances microresonator spectrometer technology by permitting room-temperature, aqueous experimental conditions, opening a regime of time-resolved single-particle experiments on non-emissive, nanoscale analytes engaged in catalytically and biologically relevant chemical dynamics.

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Section: Toward Real-time Monitoring and Control Of Single Nanoparticle Properties With A Microbubble Resonator Spectrometermentioning

confidence: 99%

mentioning

confidence: 99%

Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer

Hogan¹,

Horak²,

Ward³

et al. 2019

Preprint

Self Cite

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“…The resulting strong temperature variations largely distort the optical response via changing the refractive index and the size of the resonator, inducing a strong thermo-optical effect 1 . While the thermo-optical effect can be used for resonance wavelength tuning [2][3][4] , thermal sensing [5][6][7] , thermal locking 8,9 , and thermal imaging [10][11][12] , the heat from the light absorbed within the cavity generates undesired thermalinstability 13,14 and nonlinear dynamics [15][16][17] , and can strongly limit sensitivity and bandwidth of nanophotonic sensors 18 . A technique for experimentally distinguishing absorption losses from radiation losses with high confidence would help guide the design and fabrication strategies for nanophotonic resonators, including lowering absorptive loss rates to reduce the thermo-optical nonlinearities, as well as quantifying and harnessing these nonlinearities.…”

Section: Introductionmentioning

confidence: 99%

Using thermo-optical nonlinearity to robustly separate absorption and radiation losses in nanophotonic resonators

2021

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Low-loss nanophotonic resonators have been widely used in fundamental science and applications thanks to their ability to concentrate optical energy. Key for resonator engineering, the total intrinsic loss is easily determined by spectroscopy, however, quantitatively separating absorption and radiative losses is challenging. While the concentrated heat generated by absorption within the small mode volume results in generally unwanted thermo-optical effects, they can provide a way for quantifying absorption. Here, we propose and experimentally demonstrate a technique for separating the loss mechanisms with high confidence using only linear spectroscopic measurements. We use the optically measured resonator thermal time constant to experimentally connect the easilycalculable heat capacity to the thermal impedance, needed to calculate the absorbed power from the temperature change. We report the absorption, radiation, and coupling losses for ten whispering-gallery modes of three different radial orders on a Si microdisk. Similar absorptive loss rates are found for all the modes, despite order-of-magnitude differences in the total dissipation rate due to widely differing radiation losses. Measuring radiation losses of many modes enables distinguishing the two major components of radiation loss originating from scattering and leakage. The all-optical characterization technique is applicable to any nanophotonic resonators subject to thermo-optical effects.

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“…Besides, thermal scanning technique has been demonstrated to reduce the noise of frequency comb and optical solitons 65 . Moreover, thermal locking 66,67 and thermal imaging techniques [68][69][70] have also been developed by taking advantages of thermal instabilities and thermal absorption, respectively, which will find broad applications in sensing, microscopy, and spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Optothermal dynamics in whispering-gallery microresonators

2020

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Optical whispering-gallery-mode microresonators with ultrahigh quality factors and small mode volumes have played an important role in modern physics. They have been demonstrated as a diverse platform for a wide range of photonics applications, such as nonlinear optics, optomechanics, quantum optics, and information processing. Thermal behaviors induced by power buildup in resonators or environmental perturbations are ubiquitous in high-quality-factor whispering-gallery-mode resonators and have played an important role in their operation for various applications. Here in this review, we discuss the mechanisms of laser field induced thermal nonlinear effects, including thermal bistability and thermal oscillation. With the help of the thermal bistability effect, optothermal spectroscopy and optical non-reciprocity have been demonstrated. On the other hand, by tuning the temperature of the environment, the resonant mode frequency will shift, which could also be used for thermal sensing/tuning applications. Thermal locking technique and thermal imaging mechanisms are discussed briefly. Last, we review some techniques to realize thermal stability in a high-quality-factor resonator system.

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Single-particle photothermal imaging via inverted excitation through high-Q all-glass toroidal microresonators

Cited by 22 publications

References 52 publications

Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer

Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer

Using thermo-optical nonlinearity to robustly separate absorption and radiation losses in nanophotonic resonators

Optothermal dynamics in whispering-gallery microresonators

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