scholarly journals Measurement of Terahertz Optical-Beat Frequency Using High-Order Harmonics of Microwave in a Photoconductive Device

2011 ◽  
Vol 2011 ◽  
pp. 1-8
Author(s):  
Kengo Murasawa ◽  
Koki Sato ◽  
Takehiko Hidaka
Keyword(s):  
Measurement Error ◽  
Beat Frequency ◽  
Microwave Signal ◽  
High Order ◽  
Wave Frequency ◽  
Laser Beams ◽  
Thz Radiation ◽  
Homodyne Detection ◽  
Thz Wave ◽  
Frequency Meter

A method for measuring frequencies of the terahertz (THz) radiation emitted by the antenna mounted on the photoconductive (PC) device is presented. Two laser beams with slightly different frequencies irradiate the PC device, producing a beat current of 1 THz in the photocurrent. A microwave signal is applied to the antenna electrode. The frequency of the THz wave is measured using the homodyne detection of the optical beat with the high-order harmonics of the microwave. It is being investigated that the high-order harmonics are produced by the PC device owing to its nonlinearity. Periodic peaks generated by the homodyne detection were observed in the photocurrent, as the microwave was swept from 16 to 20 GHz with a power of −40 dBm. Using the peak frequencies, the THz-wave frequency was determined to be  GHz. The measurement error is estimated to be less than 0.43 GHz. The proposed method realizes a compact frequency meter in the THz region.

scholarly journals Strong terahertz radiation generation by cosh-Gaussian laser beams in axially magnetized collisional plasma under non-relativistic ponderomotive regime

2018 ◽  
Vol 36 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Prateek Varshney ◽  
Ajit Upadhayay ◽  
K. Madhubabu ◽  
Vivek Sajal ◽  
J. A. Chakera
Keyword(s):  
Magnetic Field ◽  
Ponderomotive Force ◽  
Beat Frequency ◽  
Magnetized Plasma ◽  
Laser Beams ◽  
Thz Radiation ◽  
Thz Wave ◽  
Oscillatory Velocity ◽  
Non Linear ◽  
Radiation Generation

AbstractWe propose a scheme for terahertz (THz) radiation generation by non-linear mixing of two cosh-Gaussian laser beams in axially magnetized plasma with spatially periodic density ripple where electron-neutral collisions have been taken into account. The laser beams exert a non-linear ponderomotive force due to spatial non-uniformity in the intensity. The plasma electrons acquire non-linear oscillatory velocity under the influence of ponderomotive force. This oscillatory velocity couples with preformed density ripples (n′ = n0αeiαz) to generate a strong transient non-linear current that resonantly derives THz radiation of frequency ~ωh (upper hybrid frequency). Laser frequencies (ω1 and ω2) are chosen such that the beat frequency (ω) lies in the THz region. The periodicity of density ripple provides phase-matching conditions (ω = ω1 − ω2 and $\vec k = \vec k_1 - \vec k_2 + {\rm \vec \alpha} $) to transfer maximum momentum from laser to THz radiation. The axially applied external magnetic field can be utilized to enhance the non-linear coupling and control various parameters of generated THz wave. The effects of decentered parameters (b), collisional frequency (νen), and magnetic field strength (B0 = ωcm/e) are analyzed for strong THz radiation generation. Analytical results show that the amplitude of THz wave enhances with decentered parameters as well as with the magnitude of axially applied magnetic field. The THz amplitude is found to be highly sensitive to collision frequency.

scholarly journals Generation of terahertz radiation from beating of two intense cosh-Gaussian laser beams in magnetized plasma

2019 ◽  
Vol 37 (4) ◽  
pp. 415-427
Author(s):  
Gunjan Purohit ◽  
Vinod Rawat ◽  
Priyanka Rawat
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Beat Frequency ◽  
Magnetized Plasma ◽  
Laser Beams ◽  
Thz Radiation ◽  
Highly Sensitive ◽  
Oscillatory Velocity ◽  
Radiation Generation ◽  
Paraxial Ray

AbstractAn analytical and numerical study has been carried out for the generation of terahertz (THz) radiation by beating of two intense cosh-Gaussian laser beams (decentered Gaussian beams) in the rippled density magnetized plasma under the relativistic–ponderomotive regime. In this process, both laser beams exert a relativistic–ponderomotive force on plasma electrons at the beat frequency and impart them an oscillatory velocity in the presence of a static magnetic field. Due to coupling between this nonlinear oscillatory velocity with density ripple, nonlinear current is generated that excites the THz radiation at the different frequency. Higher-order paraxial-ray approximation (non-paraxial theory) has been used in this study. The effects of the decentered parameter, magnetic field, and density ripple on the THz radiation generation in ripple density magnetized plasma have been investigated. Further, the effect of beating of laser beams on the THz field amplitude and the efficiency of THz radiation have been studied. The amplitude and efficiency of the emitted radiation are found to be highly sensitive to the decentered parameter, magnetic field, and density ripple. It has been found that the amplitude and efficiency of the generated THz radiation increase significantly with increasing the values of decentered parameter, magnetic field, and density ripple.

scholarly journals Design for a Highly Stable Laser Source Based on the Error Model of High-Speed High-Resolution Heterodyne Interferometers

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1083
Author(s):  
Hongxing Yang ◽  
Ziqi Yin ◽  
Ruitao Yang ◽  
Pengcheng Hu ◽  
Jing Li ◽  
...  
Keyword(s):  
Measurement Error ◽  
High Resolution ◽  
High Speed ◽  
Beat Frequency ◽  
Error Model ◽  
Laser Source ◽  
Measurement Error Model ◽  
High Resolution Measurement ◽  
Resolution Measurement ◽  
The Impact

Heterodyne interferometers with two opposite Doppler shift interference signals have been proposed for high-resolution measurement with high measurement speed, which can be used in the background of high-speed high-resolution measurement. However, a measurement error model for high-speed high-resolution heterodyne interferometers (HSHR-HIs) has not yet been proposed. We established a HSHR-HI measurement error model, analyzed the influence of beat frequency stability with a simplified optical structure, and then designed an offset-locked dual-frequency laser source with a digital control system to reduce the impact of beat frequency drift. Experiments were used to verify the correction of the measurement error model and the validity of the laser source. The results show that the new laser source has a maximum beat frequency range of 45 MHz, which shows the improvements in the measuring speed and resolution.

scholarly journals Tailoring the longitudinal electric fields of high-order laser beams and their direct verification in three dimensions

2020 ◽  
Vol 459 ◽  
pp. 124894
Author(s):  
Leevi Kallioniemi ◽  
Léo Turquet ◽  
Harri Lipsanen ◽  
Martti Kauranen ◽  
Godofredo Bautista
Keyword(s):  
Electric Fields ◽  
High Order ◽  
Three Dimensions ◽  
Laser Beams ◽  
Direct Verification

scholarly journals Strong terahertz field generation by relativistic self-focusing of hollow Gaussian laser beam in magnetoplasma

2015 ◽  
Vol 34 (1) ◽  
pp. 86-93 ◽  
Author(s):  
Saba Hussain ◽  
Ram Kishor Singh ◽  
R. P. Sharma
Keyword(s):  
Beat Frequency ◽  
Thz Radiation ◽  
Phase Matching ◽  
Electron Mass ◽  
Gaussian Laser Beam ◽  
Electron Plasma Wave ◽  
Self Focusing ◽  
Highly Sensitive ◽  
Background Magnetic Field ◽  
Density Plasma

AbstractThe present paper proposes a model for the generation of Terahertz (THz) radiation by self-focused hollow Gaussian beam (HGB) in collisionless magnetized rippled density plasma. At high intensities, the change in the electron mass occurs due to relativistic effect, introducing a nonlinearity in the plasma leading to the self-focusing of the HGB. The nonlinear interaction of this highly intense self-focused HGB with the electron plasma wave in the rippled density plasma, satisfying proper phase matching conditions, results in the resonant excitation of THz radiations at the beat frequency. We have studied the dependence of generated THz radiations on the order of the HGB as well as on the static background magnetic field. The results show that the intensity of the generated radiations is highly sensitive to both of these parameters. For the current scheme the power of the generated THz waves comes out to be of the order of Gigawatts.

Effect of high-order field corrections in electron scattering by intense laser beams in vacuum

2001 ◽  
Vol 55 (4) ◽  
pp. 492-498
Author(s):  
J. X Wang ◽  
W Scheid ◽  
M Hoelss ◽  
Y. K Ho ◽  
Q Kong
Keyword(s):  
Electron Scattering ◽  
High Order ◽  
Intense Laser ◽  
Laser Beams ◽  
High Order Field

scholarly journals Broadband THz Sources from Gases to Liquids

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yiwen E ◽  
Liangliang Zhang ◽  
Anton Tcypkin ◽  
Sergey Kozlov ◽  
Cunlin Zhang ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Laser Pulses ◽  
High Energy ◽  
Wave Generation ◽  
High Energy Density ◽  
Intense Laser ◽  
Thz Radiation ◽  
Flowing Liquid ◽  
Thz Wave ◽  
Thz Sources

Matters are generally classified within four states: solid, liquid, gas, and plasma. Three of the four states of matter (solid, gas, and plasma) have been used for THz wave generation with short laser pulse excitation for decades, including the recent vigorous development of THz photonics in gases (air plasma). However, the demonstration of THz generation from liquids was conspicuously absent. It is well known that water, the most common liquid, is a strong absorber in the far infrared range. Therefore, liquid water has historically been sworn off as a source for THz radiation. Recently, broadband THz wave generation from a flowing liquid target has been experimentally demonstrated through laser-induced microplasma. The liquid target as the THz source presents unique properties. Specifically, liquids have the comparable material density to that of solids, meaning that laser pulses over a certain area will interact with three orders more molecules than an equivalent cross-section of gases. In contrast with solid targets, the fluidity of liquid allows every laser pulse to interact with a fresh area on the target, meaning that material damage or degradation is not an issue with the high-repetition rate intense laser pulses. These make liquids very promising candidates for the investigation of high-energy-density plasma, as well as the possibility of being the next generation of THz sources.

Generation of elliptically polarized high-order harmonic radiation with bi-elliptical two-color laser beams

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Anne Weber ◽  
Birger Böning ◽  
Björn Minneker ◽  
Stephan Fritzsche
Keyword(s):  
High Order ◽  
Laser Beams ◽  
Harmonic Radiation ◽  
High Order Harmonic ◽  
Elliptically Polarized
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