14 research outputs found
Polarization dependence of semiconductor exciton and biexciton contributions to phase-resolved optical two-dimensional Fourier-transform spectra
We study the coherent light-matter interactions of GaAs quantum wells
associated with excitons, biexcitons and many-body effects. For most
polarization configurations, excitonic features dominate the phase-resolved
two-dimensional Fourier-transform (2DFT) spectra and have dispersive
lineshapes, indicating the presence of many-body interactions. For cross-linear
excitation, excitonic features become weak and absorptive due to the strong
suppression of many-body effects; a result that can not be directly determined
in transient four-wave mixing experiments. The biexcitonic features do not
weaken for cross-polarized excitation and thus are more important.Comment: 4 page, 3 figures, journal article - rapid communicatio
All-optical retrieval of the global phase for two-dimensional Fourier-transform spectroscopy
A combination of spatial interference patterns and spectral interferometry
are used to find the global phase for non-collinear two-dimensional
Fourier-transform (2DFT) spectra. Results are compared with those using the
spectrally resolved transient absorption (STRA) method to find the global phase
when excitation is with co-linear polarization. Additionally cross-linear
polarized 2DFT spectra are correctly phased using the all-optical technique,
where the SRTA is not applicable.Comment: 6 pages, 7 figures, journal publicatio
Coherent two-dimensional Fourier transform spectroscopy using a 25 Tesla resistive magnet.
We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an optical resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved using the split helix resistive magnet. Two-dimensional spectroscopy measurements based on the coherent four-wave mixing signal require phase stability. Therefore, these measurements are difficult to perform in environments prone to mechanical vibrations. Large resistive magnets use extensive quantities of cooling water, which causes mechanical vibrations, making two-dimensional Fourier transform spectroscopy very challenging. Here, we report on the strategies we used to overcome these challenges and maintain the required phase-stability throughout the measurement. A self-contained portable platform was used to set up the experiments within the time frame provided by a user facility. Furthermore, this platform was floated above the optical table in order to isolate it from vibrations originating from the resistive magnet. Finally, we present two-dimensional Fourier transform spectra obtained from GaAs quantum wells at magnetic fields up to 25 T and demonstrate the utility of this technique in providing important details, which are obscured in one dimensional spectroscopy
Atomic clock using a photodetector
In one embodiment, an atomic clock for use in an electronic device includes a photodetector with a single-isotope silicon crystal doped with impurity atoms in which a photocurrent generated via a two-photon process within the photodetector is used as a frequency resonance of the atomic clock
Atomic clock using a photodetector
In one embodiment, an atomic clock for use in an electronic device includes a photodetector with a single-isotope silicon crystal doped with impurity atoms in which a photocurrent generated via a two-photon process within the photodetector is used as a frequency resonance of the atomic clock
Silicon-based atomic clocks
In one embodiment, a silicon-based atomic clock for use in an electronic device includes a single-isotope silicon crystal and energy level transitions within the silicon are used as a frequency resonance of the clock
Coherent Two-dimensional Fourier Transform Spectroscopy using a 25 Tesla Resistive Magnet
We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an optical resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved using the split helix resistive magnet. Two-dimensional spectroscopy measurements based on the coherent four-wave mixing signal require phase stability. Therefore, these measurements are difficult to perform in environments prone to mechanical vibrations. Large resistive magnets use extensive quantities of cooling water, which causes mechanical vibrations, making two-dimensional Fourier transform spectroscopy very challenging. Here, we report on the strategies we used to overcome these challenges and maintain the required phase-stability throughout the measurement. A self-contained portable platform was used to set up the experiments within the time frame provided by a user facility. Furthermore, this platform was floated above the optical table in order to isolate it from vibrations originating from the resistive magnet. Finally, we present two-dimensional Fourier transform spectra obtained from GaAs quantum wells at magnetic fields up to 25 T and demonstrate the utility of this technique in providing important details, which are obscured in one dimensional spectroscopy
Biexcitons in Monolayer Transition Metal Dichalcogenides Tuned by Magnetic Fields
We present time-integrated four-wave mixing measurements on monolayer MoSe2 in magnetic fields up to 25 T. The experimental data together with time-dependent density function theory calculations provide interesting insights into the biexciton formation and dynamics. In the presence of magnetic fields the coherence at negative and positive time delays is dominated by intervalley biexcitons. We demonstrate that magnetic fields can serve as a control to enhance the biexciton formation and help search for more exotic states of matter, including the creation of multiple exciton complexes and excitonic condensates