Phase-shift cavity ring-down spectroscopy on a microsphere resonator by Rayleigh backscattering

Barnes, Jack A.; Gagliardi, G.; Loock, Hans‐Peter

doi:10.1103/physreva.87.053843

Cited by 13 publications

(8 citation statements)

References 34 publications

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“…Fitting algorithms, however, still play a key role in extraction of the cavity decay time, and hence an associated fitting error results. To avoid this noise use of phase-shift CDRS [225] is now frequently employed [226–229]. By amplitude modulating the input field from a CW laser (such that the rise time is less than the decay time) and monitoring the phase shift of the transmitted field, the ring-down time of the cavity τ can be determined with a time resolution set by the repetition rate of the amplitude modulation.…”

Section: Sensingmentioning

confidence: 99%

Whispering gallery mode sensors

2015

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We present a comprehensive overview of sensor technology exploiting optical whispering gallery mode (WGM) resonances. After a short introduction we begin by detailing the fundamental principles and theory of WGMs in optical microcavities and the transduction mechanisms frequently employed for sensing purposes. Key recent theoretical contributions to the modeling and analysis of WGM systems are highlighted. Subsequently we review the state of the art of WGM sensors by outlining efforts made to date to improve current detection limits. Proposals in this vein are numerous and range, for example, from plasmonic enhancements and active cavities to hybrid optomechanical sensors, which are already working in the shot noise limited regime. In parallel to furthering WGM sensitivity, efforts to improve the time resolution are beginning to emerge. We therefore summarize the techniques being pursued in this vein. Ultimately WGM sensors aim for real-world applications, such as measurements of force and temperature, or alternatively gas and biosensing. Each such application is thus reviewed in turn, and important achievements are discussed. Finally, we adopt a more forward-looking perspective and discuss the outlook of WGM sensors within both a physical and biological context and consider how they may yet push the detection envelope further.

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Section: Sensingmentioning

confidence: 99%

Whispering gallery mode sensors

2015

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“…For high modulation frequencies deviations from linearity are expected, as described in Ref. [35]. A fit of the phase-shift values obtained at different AM frequencies to Eq.…”

Section: Results and Analysismentioning

confidence: 71%

“…In addition, we also recorded the phase shift of the backscattered field. It has been shown recently that the phase shift for the backscattered light is [35,36] ΔΦ bs 2 tan −1…”

Section: Results and Analysismentioning

confidence: 99%

“…and γ is the coupling constant between near-degenerate clockwise and counterclockwise WGMs [35,36]. The coupling constant, γ, was assumed to remain unchanged throughout the adsorption process.…”

Section: Results and Analysismentioning

confidence: 99%

“…In addition, WGM resonances are observed by monitoring the light transmitted through the tapered waveguide using a second photodetector. A spectrum of a typical WGM resonance, viewed simultaneously in backscatter and transmission modes, is shown in references [35,36]. Frequency locking of the diode laser was achieved using the Pound-Drever-Hall (PDH) technique [37], as described previously [38].…”

Section: Methodsmentioning

confidence: 99%

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Absolute absorption cross-section measurement of a submonolayer film on a silica microresonator

Barnes

Gagliardi

Loock

2014

Optica

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Conventional absorption spectroscopy is not nearly sensitive enough for quantitative overtone measurements on submonolayer coatings. While cavity-enhanced absorption detection methods using microresonators have the potential to provide quantitative absorption cross sections of even weakly absorbing submonolayer films, this potential has not yet been fully realized. To determine the absorption cross section of a submonolayer film of ethylene diamine (EDA) on a silica microsphere resonator, we use phase-shift cavity ringdown spectroscopy simultaneously on near-IR radiation that is Rayleigh backscattered from the microsphere and transmitted through the coupling fiber taper. We then independently determine both the coupling coefficient and the optical loss within the resonator. Together with a coincident measurement of the wavelength frequency shift, an absolute overtone absorption cross section of adsorbed EDA, at submonolayer coverage, was obtained and was compared to the bulk value. The smallest quantifiable absorption cross section is σ min 2.7 × 10 −12 cm 2. This absorption cross section is comparable to the extinction coefficients of, e.g., single gold nanoparticles or aerosol particles. We therefore propose that the present method is also a viable route to absolute extinction measurements of single particles.

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Optical Microresonators for Sensing and Transduction: A Materials Perspective

et al. 2017

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Optical microresonators confine light to a particular microscale trajectory, are exquisitely sensitive to their microenvironment, and offer convenient readout of their optical properties. Taken together, this is an immensely attractive combination that makes optical microresonators highly effective as sensors and transducers. Meanwhile, advances in material science, fabrication techniques, and photonic sensing strategies endow optical microresonators with new functionalities, unique transduction mechanisms, and in some cases, unparalleled sensitivities. In this progress report, the operating principles of these sensors are reviewed, and different methods of signal transduction are evaluated. Examples are shown of how choice of materials must be suited to the analyte, and how innovations in fabrication and sensing are coupled together in a mutually reinforcing cycle. A tremendously broad range of capabilities of microresonator sensors is described, from electric and magnetic field sensing to mechanical sensing, from single-molecule detection to imaging and spectroscopy, from operation at high vacuum to in live cells. Emerging sensing capabilities are highlighted and put into context in the field. Future directions are imagined, where the diverse capabilities laid out are combined and advances in scalability and integration are implemented, leading to the creation of a sensor unparalleled in sensitivity and information content.

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Phase-shift cavity ring-down spectroscopy on a microsphere resonator by Rayleigh backscattering

Cited by 13 publications

References 34 publications

Whispering gallery mode sensors

Whispering gallery mode sensors

Absolute absorption cross-section measurement of a submonolayer film on a silica microresonator

Optical Microresonators for Sensing and Transduction: A Materials Perspective

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