scholarly journals Interferometers with Internal and External Phase Modulation: Experimental and Analytical Comparison

1995 ◽  
Vol 48 (6) ◽  
pp. 971 ◽  
Author(s):  
Andrew J Stevenson ◽  
Malcolm B Gray ◽  
Charles C Harb ◽  
David E McClelland ◽  
Hans-A Bachor
Keyword(s):  
Shot Noise ◽  
High Frequency ◽  
Phase Modulation ◽  
Low Frequency ◽  
Local Oscillator ◽  
Intensity Noise ◽  
Fringe Contrast ◽  
Limited Region ◽  
External Modulation ◽  
Frequency Phase

Optical intensity noise in a light source easily degrades the sensitivity of a shot-noise-limited interferometer which is directly detecting low frequency phase or displacement variations. In this paper we describe and compare two experimental methods in which we use high frequency optical phase modulation to shift low frequency phase signals in an interferometer to a shot noise limited region of the photocurrent spectrum. This phase modulation is applied either within the interferometer arms-internal modulation-or in a local oscillator beam tapped off the main interferometer and coherently recombined with the interferometer output-external modulation. he photocurrent is mixed electronically with the high frequency modulating waveform to extract the signal information free from laser intensity noise. In our experiments, we have been able to detect interferometrically low frequency signals with true shot-noise-limited sensitivity. We find, theoretically and experimentally, that the interferometric sensitivity achievable in each scheme depends critically on non-ideal factors, such as imperfect interferometric fringe contrast and electronic noise in the detectors or amplifiers. This paper examines the relative merits and operating requirements of both modulation schemes in practical interferometers.

scholarly journals Low-frequency phase measurement with high-frequency squeezing

2012 ◽  
Vol 20 (16) ◽  
pp. 18173 ◽  
Author(s):  
Zehui Zhai ◽  
Jiangrui Gao
Keyword(s):  
High Frequency ◽  
Phase Measurement ◽  
Low Frequency ◽  
Frequency Phase

Shot-Noise Limited Low-Frequency Intensity Noise of a Nd:YAG Laser

1992 ◽  
Vol 31 (Part 1, No. 4) ◽  
pp. 1241-1242 ◽  
Author(s):  
Kimio Tsubono ◽  
Shigenori Moriwaki
Keyword(s):  
Shot Noise ◽  
Nd:Yag Laser ◽  
Low Frequency ◽  
Intensity Noise ◽  
Frequency Intensity

Design and Research on Piezoelectric Acceleration Geophone

2012 ◽  
Vol 468-471 ◽  
pp. 826-830 ◽  
Author(s):  
Ya Min Xing ◽  
Sheng Hu Liu ◽  
Dong Xu Wang
Keyword(s):  
High Frequency ◽  
Detection Method ◽  
Low Frequency ◽  
Response Characteristic ◽  
Piezoelectric Crystal ◽  
Field Test Result ◽  
Test Result ◽  
Higher Sensitivity ◽  
Frequency Phase ◽  
Piezoelectric Acceleration

A kind of piezoelectricity acceleration geophone is studied and discussed. carried on its amplitude frequency, phase-frequency characteristic theoretically, obtained the primary factor of the influence on frequency response, and improved in the piezoelectric crystal choice and geophone structure. The theory and the field test result indicated that, this piezoelectricity acceleration geophone has better response characteristic on low frequency and the high-frequency as well as a higher sensitivity, it is one better detection method.

scholarly journals A statistical framework to assess cross-frequency coupling while accounting for confounding analysis effects

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jessica K Nadalin ◽  
Louis-Emmanuel Martinet ◽  
Ethan B Blackwood ◽  
Meng-Chen Lo ◽  
Alik S Widge ◽  
...  
Keyword(s):  
High Frequency ◽  
Statistical Power ◽  
Brain Activity ◽  
Low Frequency ◽  
Modeling Framework ◽  
Frequency Coupling ◽  
Phase Amplitude ◽  
Cross Frequency Coupling ◽  
Frequency Phase

Cross frequency coupling (CFC) is emerging as a fundamental feature of brain activity, correlated with brain function and dysfunction. Many different types of CFC have been identified through application of numerous data analysis methods, each developed to characterize a specific CFC type. Choosing an inappropriate method weakens statistical power and introduces opportunities for confounding effects. To address this, we propose a statistical modeling framework to estimate high frequency amplitude as a function of both the low frequency amplitude and low frequency phase; the result is a measure of phase-amplitude coupling that accounts for changes in the low frequency amplitude. We show in simulations that the proposed method successfully detects CFC between the low frequency phase or amplitude and the high frequency amplitude, and outperforms an existing method in biologically-motivated examples. Applying the method to in vivo data, we illustrate examples of CFC during a seizure and in response to electrical stimuli.

scholarly journals Visualization of Phase-Amplitude Coupling Using Rhythmic High-Frequency Activity

2020 ◽  
Author(s):  
Hiroaki Hashimoto ◽  
Hui Ming Khoo ◽  
Takufumi Yanagisawa ◽  
Naoki Tani ◽  
Satoru Oshino ◽  
...  
Keyword(s):  
High Frequency ◽  
Focal Epilepsy ◽  
Low Frequency ◽  
Θ Rhythm ◽  
Human Epilepsy ◽  
High Frequency Activity ◽  
Phase Amplitude ◽  
Intracranial Electrode ◽  
Intracranial Electrodes ◽  
Frequency Phase

AbstractObjectiveHigh-frequency activities (HFAs) and phase-amplitude coupling (PAC) are gaining attention as key neurophysiological biomarkers for studying human epilepsy. We aimed to clarify and visualize how HFAs are modulated by the phase of low-frequency bands during seizures.MethodsWe used intracranial electrodes to record seizures of symptomatic focal epilepsy (15 seizures in seven patients). Ripples (80–250 Hz), as representative of HFAs, were evaluated along with PAC. The synchronization index (SI), representing PAC, was used to analyze the coupling between the amplitude of ripples and the phase of lower frequencies. We created a video in which the intracranial electrode contacts were represented by circles that were scaled linearly to the power changes of ripple.ResultsThe main low frequency band modulating ictal-ripple activities was the θ band (4–8 Hz), and after completion of ictal-ripple burst, δ (1–4 Hz)-ripple PAC occurred. The video showed that fluctuation of the diameter of these circles indicated the rhythmic changes during significant high values of θ-ripple PAC.ConclusionsWe inferred that ripple activities occurring during seizure evolution were modulated by θ rhythm. In addition, we concluded that rhythmic circles’ fluctuation presented in the video represents the PAC phenomenon. Our video is thus a useful tool for understanding how ripple activity is modulated by the low-frequency phase in relation with PAC.

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