skip to main content

Title: Forward terahertz wave generation from liquid gallium in the non-relativistic regime

We characterize a terahertz (THz) source based on plasma in liquid gallium. The dependence of the emitted THz pulse energy on second-order phase, pump pulse energy, and polarization of the short laser pulse is demonstrated. Our study suggests that the THz emission mechanism is due to the ponderomotive force and is aided by a direct-field driven term. The proposed source and accompanying generation mechanism are studied under a non-relativistic regime (1015<<#comment/>I<<#comment/>1018W/cm2) for forward directed THz under a single pump excitation scheme.

more » « less
Award ID(s):
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Journal of the Optical Society of America B
0740-3224; JOBPDE
Page Range / eLocation ID:
Article No. 3639
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. The mid-IR spectroscopic properties ofEr3+doped low-phononCsCdCl3andCsPbCl3crystals grown by the Bridgman technique have been investigated. Using optical excitations at∼<#comment/>800nmand∼<#comment/>660nm, both crystals exhibited IR emissions at∼<#comment/>1.55,∼<#comment/>2.75,∼<#comment/>3.5, and∼<#comment/>4.5µ<#comment/>mat room temperature. The mid-IR emission at 4.5 µm, originating from the4I9/2→<#comment/>4I11/2transition, showed a long emission lifetime of∼<#comment/>11.6msforEr3+dopedCsCdCl3, whereasEr3+dopedCsPbCl3exhibited a shorter lifetime of∼<#comment/>1.8ms. The measured emission lifetimes of the4I9/2state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the4I9/2→<#comment/>4I11/2transition inEr3+dopedCsCdCl3andCsPbCl3were determined to be∼<#comment/>0.14×<#comment/>10−<#comment/>20cm2and∼<#comment/>0.41×<#comment/>10−<#comment/>20cm2, respectively. The results of Judd–Ofelt analysis are presented and discussed.

    more » « less
  2. We experimentally demonstrate simultaneous turbulence mitigation and channel demultiplexing in a 200 Gbit/s orbital-angular-momentum (OAM) multiplexed link by adaptive wavefront shaping and diffusing (WSD) the light beams. Different realizations of two emulated turbulence strengths (the Fried parameterr0=0.4,1.0mm) are mitigated. The experimental results show the following. (1) Crosstalk between OAMl=+1andl=−<#comment/>1modes can be reduced by><#comment/>10.0and><#comment/>5.8dB, respectively, under the weaker turbulence (r0=1.0mm); crosstalk is further improved by><#comment/>17.7and><#comment/>19.4dB, respectively, under most realizations in the stronger turbulence (r0=0.4mm). (2) The optical signal-to-noise ratio penalties for the bit error rate performance are measured to be∼<#comment/>0.7and∼<#comment/>1.6dBunder weaker turbulence, while measured to be∼<#comment/>3.2and∼<#comment/>1.8dBunder stronger turbulence for OAMl=+1andl=−<#comment/>1mode, respectively.

    more » « less
  3. Here, we reportχ<#comment/>(3)-based optical parametric oscillation (OPO) with widely separated signal–idler frequencies from crystalline aluminum nitride microrings pumped at2µ<#comment/>m. By tailoring the width of the microring, OPO reaching toward the telecom and mid-infrared bands with a frequency separation of 64.2 THz is achieved. While dispersion engineering through changing the microring width is capable of shifting the OPO sideband by><#comment/>9THz, the OPO frequency can also be agilely tuned in the ranges of 1 and 0.1 THz, respectively, by shifting the pump wavelength and controlling the chip’s temperature. At high pump powers, the OPO sidebands further evolve into localized frequency comb lines. Such large-frequency-shift OPO with flexible wavelength tunability will lead to enhanced chip-scale light sources.

    more » « less
  4. For easy manipulation of polarization states of light for applications in communications, imaging, and information processing, an efficient mechanism is desired for rotating light polarization with a minimum interaction length. Here, we report giant polarization rotations for terahertz (THz) electromagnetic waves in ultrathin (∼<#comment/>45nm), high-density films of aligned carbon nanotubes. We observed polarization rotations of up to∼<#comment/>20∘<#comment/>and∼<#comment/>110∘<#comment/>for transmitted and reflected THz pulses, respectively. The amount of polarization rotation was a sensitive function of the angle between the incident THz polarization and the nanotube alignment direction, exhibiting a “magic” angle at which the total rotation through transmission and reflection becomes exactly 90°. Our model quantitatively explains these giant rotations as a result of extremely anisotropic optical constants, demonstrating that aligned carbon nanotubes promise ultrathin, broadband, and tunable THz polarization devices.

    more » « less
  5. We report on spectroscopic measurements on the4f76s28S7/2∘<#comment/>→<#comment/>4f7(8S∘<#comment/>)6s6p(1P∘<#comment/>)8P9/2transition in neutral europium-151 and europium-153 at 459.4 nm. The center of gravity frequencies for the 151 and 153 isotopes, reported for the first time in this paper, to our knowledge, were found to be 652,389,757.16(34) MHz and 652,386,593.2(5) MHz, respectively. The hyperfine coefficients for the6s6p(1P∘<#comment/>)8P9/2state were found to beA(151)=−<#comment/>228.84(2)MHz,B(151)=226.9(5)MHzandA(153)=−<#comment/>101.87(6)MHz,B(153)=575.4(1.5)MHz, which all agree with previously published results except for A(153), which shows a small discrepancy. The isotope shift is found to be 3163.8(6) MHz, which also has a discrepancy with previously published results.

    more » « less