scholarly journals Tailoring of multi-pulse dynamics in mode-locked laser via optoacoustic manipulation of quasi-continuous-wave background

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Ki Sang Lee ◽  
Chang Kyun Ha ◽  
Kyoung Jun Moon ◽  
Dae Seok Han ◽  
Myeong Soo Kang
Keyword(s):  
Information Processing ◽  
Time Domain ◽  
Continuous Wave ◽  
Single Pulse ◽  
Laser Cavity ◽  
Temporal Position ◽  
Optical Information ◽  
Pulse Dynamics ◽  
Mode Locked Laser ◽  
The Time Domain

Abstract Various nonequilibrium multi-pulse states can emerge in a mode-locked laser through interactions between the quasi-continuous-wave background (qCWB) and pulses inside the laser cavity. While they have been regarded as unpredictable and hardly controllable due to the noise-like nature of qCWB, we here demonstrate that the qCWB landscape can be manipulated via optoacoustically mediated pulse-to-qCWB interactions, which alters the behaviors of multi-pulse dynamics. In this process, impulsive qCWB modulations are created at well-defined temporal locations, which act as the point emitters and attractive potentials for drifting pulse bunches and soliton rains. Hence, we can transport a single pulse bunch from a certain temporal position to another, and also make soliton rains created and collided exclusively at specific temporal locations. Our study opens up possibilities to control the nonequilibrium multi-pulse phenomena precisely in the time domain, which would offer a practical means of advanced optical information processing.

scholarly journals Archimedean Spiral Antenna Calibration Procedures to Increase the Downrange Resolution of a SFCW Radar

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Ioan Nicolaescu ◽  
Piet van Genderen
Keyword(s):  
Time Domain ◽  
Continuous Wave ◽  
Phase Variation ◽  
Antenna System ◽  
Spiral Antenna ◽  
Multiple Reflections ◽  
Archimedean Spiral ◽  
Wave Radar ◽  
Time Domain Response ◽  
The Time Domain

This paper deals with the calibration procedures of an Archimedean spiral antenna used for a stepped frequency continuous wave radar (SFCW), which works from 400 MHz to 4845 MHz. Two procedures are investigated, one based on an error-term flow graph for the frequency signal and the second based on a reference metallic plate located at a certain distance from the ground in order to identify the phase dispersion given by the antenna. In the second case, the received signal is passed in time domain by applying an ifft, the multiple reflections are removed and the phase variation due to the time propagation is subtracted. After phase correction, the time domain response as well as the side lobes level is decreased. The antenna system made up of two Archimedean spirals is employed by SFCW radar that operates with a frequency step of 35 MHz.

Information processing with spectral decomposition of ultrafast pulses in the time domain

2006 ◽  
Author(s):  
Robert E. Saperstein ◽  
Nikola Alic ◽  
Dmitriy Panasenko ◽  
Xiaobo Xie ◽  
Paul K. L. Yu ◽  
...  
Keyword(s):  
Information Processing ◽  
Time Domain ◽  
Spectral Decomposition ◽  
Ultrafast Pulses ◽  
The Time Domain

Inapplicability of pulse train time‐domain measurements to spectral induced polarization

Geophysics ◽  
1984 ◽  
Vol 49 (6) ◽  
pp. 826-827 ◽  
Author(s):  
Heikki Soininen
Keyword(s):  
Time Domain ◽  
Pulse Train ◽  
Apparent Resistivity ◽  
Single Pulse ◽  
Induced Polarization ◽  
Spectral Measurements ◽  
Frequency Spectra ◽  
Voltage Transient ◽  
The Fourier Transform ◽  
The Time Domain

The method of induced polarization (IP) is based on the frequency dependence of resistivity of rocks. In spectral IP the apparent resistivity is measured at a wide‐frequency band (e.g., 1/1024…4096 Hz). The apparent resistivity depends upon the distribution of the resistivity of the earth according to the laws of electromagnetism. On the basis of their spectral measurements Pelton et al. (1978) proposed that variations in mineral texture give rise to variations in the frequency spectra of resistivity. It should thus be feasible to use these spectra to discriminate between, say, graphite and sulfides. The frequency domain and the time domain are equivalent in a linear and causal system, the domains being interrelated through the Fourier transform. The time domain is attractive in that the whole transient can be recorded in a single measurement. Hence, there are devices in commercial use that record spectra in the time domain by measuring the voltage transient at a number of instances after the current pulse has been switched off. The primary current signal in these devices is generally a pulse train composed of pulses of finite duration. The pulse train has advantages over the single pulse because it permits the measurements to be repeated and thus improves the signal‐to‐noise (S/N) ratio of the measurements.

Apodisation in the time domain

1992 ◽  
Vol 2 (4) ◽  
pp. 615-620
Author(s):  
G. W. Series
Keyword(s):  
Time Domain ◽  
The Time Domain

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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