Controling the coupling properties of active ultrahigh-Q WGM microcavities from undercoupling to selective amplification

Rasoloniaina, Alphonse; Huet, Vincent; Nguyên, Thị Kim Ngân; Cren, Élodie Le; Mortier, Michel; Michely, Laurent; Dumeige, Yannick; Féron, Patrice

doi:10.1038/srep04023

Cited by 51 publications

(43 citation statements)

References 49 publications

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“…Many unique properties of optical WGMs, e.g. ultra-high quality (Q) factors and small cavity sizes, make them suitable for a variety of applications, such as all-optical switches1, laser sources23, filters45, sensors467, and quantum computing8. WGM-based highly-sensitive sensing has drawn great attention because WGM cavities are able to confine the optical field in a very small space for an extended time period, which greatly enhances the interaction between the optical field and the analyte46910.…”

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Ringing phenomenon in chaotic microcavity for high-speed ultra-sensitive sensing

Chen¹,

Liu²,

Zhang³

et al. 2016

Sci Rep

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The ringing phenomenon in whispering-gallery-mode (WGM) microcavities has demonstrated its great potential for highly-sensitive and high-speed sensing. However, traditional symmetric WGM microcavities have suffered from an extremely low coupling efficiency via free-space coupling because the emission of symmetric WGMs is non-directional. Here we report a new approach for high-speed ultra-sensitive sensing using the ringing phenomenon in a chaotic regime. By breaking the rotational symmetry of a WGM microcavity and introducing chaotic behaviors, we show that the ringing phenomenon in chaotic WGM microcavities extends over both the positive and the negative frequency detune, allowing the ringing phenomenon to interact with analytes over a much broader bandwidth with a reduced dead time. Because the coupling of the chaotic microcavity is directional, it produces a significantly higher signal output, which improves its sensitivity without the need of a fiber coupler.

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“…When the frequency chirp rate of the laser is increased for high-speed sensing, a ringing phenomenon (RP) in the mapped WGM spectrum occurs3. Traditionally, the RP in a symmetric WGM microcavity is used to measure the Q-factor and the mode-coupling strength413.…”

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confidence: 99%

Ringing phenomenon in chaotic microcavity for high-speed ultra-sensitive sensing

Chen¹,

Liu²,

Zhang³

et al. 2016

Sci Rep

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“…A transient ringing effect [29,30] is observable even if the laser is scanned as quickly as 25 MHz/μs [31]. The ringing spectrum can be used to distinguish between the overcoupled and undercoupled cases [32]. When the scanning speed is faster than the character speed, as defined in [28], the steady-state treatment can no longer be used to describe the coupled mode system.…”

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Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

et al. 2016

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generation [1,2], laser stabilization [3][4][5] and sensing [6,7]. The high optical quality factor (Q-factor) and relatively small mode volume of whispering gallery resonators (WGRs) render the modes very sensitive to subtle environmental changes. Until now, WGRs have been used to measure changes in a number of parameters such as refractive index [8,9], temperature [10][11][12], pressure [13,14] and stress [15,16]. Aside from parameter change detection, ultrahigh Q resonators have also been used to detect nanoparticles [17,18] and single viruses [19,20]. The mechanism behind ultrahigh sensitivity sensing in WGRs is based on a reactive (i.e. dispersive) frequency shift of the whispering gallery modes [19] as a result of perturbations that may be present. Alternatively, a perturbation may increase the optical linewidth of the WGM by introducing more dissipation [21,22], or may change the back-scattering strength [23] and subsequent mode splitting if modal coupling is present [17,20]. The optomechanical properties of WGRs can also be used for force [24] or viscosity sensing [25].Currently, in order to retrieve the dispersive, dissipative and mode splitting information, the transmission spectrum of a WGR through an externally coupled waveguide, such as a tapered optical fibre, is usually measured. Light from a tunable laser source is coupled into the tapered fibre and the transmission is monitored. Low powers are used in order to minimise thermal and nonlinear effects on the whispering gallery modes. By sweeping the laser frequency, the transmission spectrum through the fibre can be recorded. Any changes to the frequency, mode splitting or linewidth are used to monitor perturbations induced by the physical parameter that is being sensed. During measurements, the transmission spectrum represents a steady state of the coupled system; therefore, time response of the sensor [26][27][28] is related to the lifetime of the resonator which limits the scanning speed. For a WGR with Abstract In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady-state transmission spectrum through the coupling waveguide. Alternatively, sensing based on cavity ring-up spectroscopy, i.e. CRUS, can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh Q-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which may improve the data collection rate.

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“…For practice applications, the high Q factor and ER of the DSR sensor are required. For a ring resonator based on the same SOI substrate, the bend loss can be neglected once the bending radius is more than 5 μm [18] , so the Q factor of the DSR mainly depends on the propagation loss and coupling loss [19] if all the radii of the semirings that are over 5 μm. The ER depends strongly on the coupling loss, so it will reach a maximal value at a critical coupling point where the coupling loss equals the intrinsic loss.…”

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Single-waveguide-based microresonators for optical sensing

et al. 2017

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Optical biosensors with a high sensitivity and a low detection limit play a highly significant role in extensive scenarios related to our daily life. Combined with a specific numerical simulation based on the transfer matrix and resonance condition, the idea of novel single-waveguide-based microresonators with a double-spiral-racetrack (DSR) shape is proposed and their geometry optimizations and sensing characteristics are also investigated based on the Vernier effect. The devices show good sensing performances, such as a high quality factor of 1.23 × 10 5 , a wide wavelength range of over 120 nm, a high extinction ratio (ER) over 62.1 dB, a high sensitivity of 698.5 nm/RIU, and a low detection limit of 1.8 × 10 −5 . Furthermore, single-waveguide-based resonators can also be built by cascading two DSR structures in series, called twin-DSRs, and the results show that the sensing properties are enhanced in terms of quasi free spectral range (FSR) and ER due to the double Vernier effect. Excellent features indicate that our novel single-waveguide-based resonators have the potential for future compact and highly integrated biosensors.

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Controling the coupling properties of active ultrahigh-Q WGM microcavities from undercoupling to selective amplification

Cited by 51 publications

References 49 publications

Ringing phenomenon in chaotic microcavity for high-speed ultra-sensitive sensing

Ringing phenomenon in chaotic microcavity for high-speed ultra-sensitive sensing

Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

Single-waveguide-based microresonators for optical sensing

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