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Two orthogonal-polarized pulse trains are simultaneously emitted from a single, all-polarization-maintaining fiber laser using two saturable absorber mirrors. This design shows great potential to reduce the complexity of current time-resolved measurement systems without sacrificing performance.
We present results from a TDS imaging system for non-destructive evaluation of aeronautics composite materials, like glass fiber laminate and sandwich structures. Time-of-flight information from reflection measurements allows for 3D reconstruction of test sample volumes. Clear identification and spatial positioning of defects like delamination and foreign inclusion is possible.
We present a comparison of fast optical sampling in a THz time domain system using ASOPS and ECOPS and a conventional opto-mechanical TDS based system. The system is operated both with the fundamental (1560 nm) and the frequency doubled output of a fiber laser. LT-GaAs based photoconductive switches are applied as THz emitters and detectors.
We report realization of a THz camera based on electro-optical detection of THz radiation from an optical parametric oscillator, using a silicon-based CCD camera as the optical detector. The dynamic range of 16.5 dB for a 6000-frame average (2-minute data acquisition time) is limited by laser noise.
We have built a THz system for one-dimensional imaging with a THz line focus and electro-optic detection based on two line-scan cameras in a balanced arrangement. The system uses pulsed THz radiation generated with a fast-repetition-rate (80 MHz) femtosecond laser and an electrically chopped dipole antenna.
We successfully realized electro-optical detection of nanosecond THz pulses based on a THz optical parametric oscillator. A maximum dynamic range of ∼30 dB/ Hz is achieved in the electro-optical measurements.
Resonant magneto-inductive surface waves at terahertz frequencies are investigated on metamaterials consisting of split-ring resonators. The excitation of surface waves is observed in transmission experiments and numerical calculations.
We present a nanosecond optical parametric oscillator for terahertz generation in periodically poled lithium niobate. The used QPM-scheme based on periodic poling leads to a collinear pump and signal wave and an emission of the terahertz wave under the well known Cherenkov-angle.
We present recent progress in on-the-fly broadband raster transmission and reflection terahertz imaging with a focus on the data evaluation. Possibilities to enhance the resolution by frequency domain filtering as well as terahertz tomography are discussed.
A nanosecond OPO pumped by a Q-switched Nd:YVO4 laser for terahertz generation in periodically poled lithium niobate with a new pattern is presented. Characteristic properties of the OPO including cascaded processes are discussed.
A high speed optical delay line in combination with a fiber-coupled terahertz time domain spectroscopy system allows for scan rates up to 200 Hz, a spectral resolution of about 10 GHz and a bandwidth of 3 THz.
A nanosecond OPO pumped by a single mode Q-switched Nd:YVO4 laser for terahertz generation in slant stripe periodically poled lithium niobate is presented. The oscillation threshold is overcome by stabilized pump enhancement and lowered by means of injection seeding by a grating stabilized, tunable diode laser.
We report on an actively controlled enhancement cavity for terahertz generation using optical rectification in lithium niobate. By recycling the transmitted fundamental laser power from a Ti:Sapphire laser an increased pump power is available for the nonlinear process. Therefore a much higher THz signal is obtained in relation to single-pass geometry. Terahertz intensities generated by different emitters...
We report on the efficient Cherenkov-type terahertz (THz) generation using lithium niobate crystals and a high repetition rate femtosecond laser. An actively length controlled synchronously pumped ring resonator acts as an enhancement cavity for the near infrared pump and therefore recycles the available pump power towards a higher terahertz output. A seven times higher THz field amplitude was measured...
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