Journal: Sensors (Basel, Switzerland)

Article Title: Acoustic, Phononic, Brillouin Light Scattering and Faraday Wave-Based Frequency Combs: Physical Foundations and Applications

doi: 10.3390/s22103921

Figure Lengend Snippet: ( a ) Schematic of the OFC generation using a mode-locked laser. The top panel shows a train of optical pulses with a period 1 / f r e p . The bottom panel depicts the spectrum of narrow frequency peaks corresponding to the train of pulses in the time domain. The phase shift Δ ϕ of the carrier wave with respect to the pulse envelope induces a translation f 0 = f r e p Δ ϕ / π of spectral peaks from their harmonic frequencies n f r e p . Reproduced from with permission from Elsevier. ( b ) Sketch of an OFC-based spectroscopy technique. The OFC as a broadband light source interrogates an absorbing sample and a spectrometer analyses the transmission spectrum. ( c ) Artist’s rendition of a Kerr effect-based OFC generation in a micro-photonic disc resonator. A continuous-wave (CW) input pump wave creates a pattern of optical whispering-gallery modes (WGMs) inside the disc resonator, thereby inducing a periodic light intensity modulation and thus producing an output signal with an OFC-like spectrum. The bottom panel shows the sketch of a simplified experimental setup for the generation of a Kerr OFC and its further processing using a photodetector (PD). Reproduced from published by De Gruyter Open under a Creative Commons License.

Article Snippet: For some practical applications, OFCs can be generated using an electro-optical modulation of a continuous wave laser light.

Techniques: Spectroscopy, Transmission Assay

Journal: Sensors (Basel, Switzerland)

Article Title: Acoustic, Phononic, Brillouin Light Scattering and Faraday Wave-Based Frequency Combs: Physical Foundations and Applications

doi: 10.3390/s22103921

Figure Lengend Snippet: ( a ) Measured time-domain acoustic response of gas bubbles. The time between the vertical dashed lines is Δ T = 1 / f n a t ≈ 0.6 ms, where f n a t is the natural frequency of the bubble oscillations (see for details). The insets show a closeup of the waveforms and demonstrate the amplitude modulation. ( b ) Experimental AFC spectra obtained using gas bubbles in water insonated with an f 0 = 24.6 kHz sinusoidal signal of increasing pressure amplitude α = 1.15, 3.75, 4, 4.2, 4.3, 7.5 and 11.5 kPa. The scattered pressure values (in dB) are shown along the vertical axis with a vertical offset of 30 dB between the spectra. Reproduced from published by Springer Nature under the terms of the Creative Commons CC BY license.

Article Snippet: For some practical applications, OFCs can be generated using an electro-optical modulation of a continuous wave laser light.

Techniques:

Journal: Sensors (Basel, Switzerland)

Article Title: Acoustic, Phononic, Brillouin Light Scattering and Faraday Wave-Based Frequency Combs: Physical Foundations and Applications

doi: 10.3390/s22103921

Figure Lengend Snippet: ( a ) Experimental average response of an ethanol drop subjected to vertical vibration at 70 Hz plotted as a function of the vibration amplitude. The inset shows the power spectra obtained by Fourier-transforming the measured signals. The parenthetical labels relate the spectra to the experimental points in the main panel. ( b ) Experimental average response of a canola oil drop subjected to vertical vibration at 70 Hz plotted as a function of the vibration amplitude. The modulation sidebands (the spectrum label 7) are present in the ethanol drop spectra and absent in the spectra of a canola oil drop. The shaded regions in the main panels correspond to the chaotic oscillations, resulting in strong diffuse scattering leading to a decrease in the optical intensity of the detected signal. Reproduced from . Copyright 2019 by the American Physical Society.

Article Snippet: For some practical applications, OFCs can be generated using an electro-optical modulation of a continuous wave laser light.

Techniques: