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Laser-ionization of molecules is one of the most important processes in the strong-field and attosecond sciences. One of the key mechanisms governing molecular ionization is enhanced ionization, where for diatomic molecules the ionization probability becomes strongly enhanced at a critical internuclear distance [1, 2]. Experiments on polytatomic molecules have revealed remarkably high charge states...
Continuous wave (CW) terahertz (THz) sources are highly desirable for a plethora of applications ranging from spectroscopy [1] over quality inspection [2,3] of industrial goods to THz astronomy [4]. It is, however, still challenging to generate decent power levels from tunable room-temperature sources; in particular in the frequency window between 1 and 5 THz. Here, we present a compact, tunable room-temperature...
We study the temporal stability of two-color emission in vertical-external-cavity surface-emitting lasers via streak-camera measurements. Dynamically stable and unstable regions are found and the dependence on the pump conditions is analyzed.
We present a cost efficient delay technique for terahertz spectrometers based on discrete phase shifting of the THz wave. This can be achieved by using a polymer disc with segments of different thickness. The approach is demonstrated by measurements with a six segment disc placed in the THz beam.
We present broadband terahertz spectroscopy systems based on continuous wave multi-mode laser diodes. By using commercial lasers with equidistant mode spacing we obtain signals similar to that of conventional time domain spectrometers.
A strip detector readout chip used in an individual photon counting detection system for precision Compton polarimetry has been chosen as a platform for the implementation, comparison and the in-silicon test of several alternative architectural analog and digital circuit concepts. For this application first an analytic result for the noise optimization has been derived based on the EKV model which...
The authors report on the direct observation of a higher-order dressed state in the transmission spectrum of an optical cavity QED system. A single trapped rubidium atom is coupled to the mode of a high-finesse optical resonator. When the system is probed at low input power, only single photon transitions are driven and the transmission spectrum shows the normal modes. By increasing the probe power,...
We present a THz time-domain spectrometer based on an 830 nm all semiconductor femtosecond laser system. Optical pulses with durations of less than 600 fs are used to gate standard LT-GaAs antennas. We achieve a signal to noise ratio of more than 40 dB in intensity and a bandwidth of 1.4 THz. Simulations based on the Drude-Lorentz model show a good agreement with the measured THz signals. Spectroscopic...
We have devolved 1064 nm high-power monolithic distributed feedback lasers which operate simultaneously on two longitudinal modes. These modes correspond to the fundamental and first-order lateral mode and arise from a 7.5 mum width ridge waveguide supporting both of them. They are further stabilized by a first-order grating built into an InGaP/GaAs/InGaP multilayer structure. The threshold current...
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