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Stimulated THz emission from intra-excitonic 3p to 2s transitions in Cu2O is directly observed by ultrafast opto-electronics. The process occurs at a photon energy of 6.6 meV, with a cross section of ~10-14 cm2.
We show theoretically how electrical and pure spin AC currents can be optically injected in semiconductors via excitation of continuum carriers. The electrical current should be observable by detecting its THz radiation.
Pulses from an ultrafast oscillator are conditioned, amplified, and delivered in an all-optical-fiber architecture. Combined with an electro-optic receiver, the complete system delivers a 4-V electrical trigger with less than 400 fs additive jitter.
We demonstrate generation of few-cycle THz pulses through optical rectification in organic DAST crystals at telecommunication wavelength (1550 nm). An extremely high conversion efficiency is achieved through velocity-matching and the materialpsilas large nonlinear optical susceptibility.
We demonstrate a muW-level broadly tunable THz source based on parametric down-conversion in orientation-patterned GaAs pumped by femtosecond pulses from a Tm-doped fiber laser. Generated THz powers should be scalable to mW-levels with this approach.
A simple non-iterative electric field retrieval method using a sinusoidally driven optical phase modulator is proposed. The method is validated by demonstrating accurate characterization of picosecond pulses used in telecommunication.
We demonstrate a dispersion-free split mirror interferometric autocorrelator suitable for measuring pulses with durations from hundreds of attoseconds to tens of femtoseconds and spectral content from the near-UV to near-IR.
We demonstrate control of the sign and magnitude of self-steepening in quadratic media. Consequently, the self-steepening-like distortions due to group-velocity mismatch can be enhanced or cancelled, which allows new applications in the near-single-cycle regime.
A high-resolution THz-spectrometer without mechanical delay-line is demonstrated. THz-field-transients with 1 ns duration are acquired at 9 kHz scan-rate. Spectra up to 3 THz are obtained with a 40 dB signal-to-noise ratio within 250 s of total measurement time.
We present a novel setup for characterizing DUV femtosecond pulses and investigating ultrafast phenomena. This allows us to directly utilize femtosecond pulses for spectroscopic applications without changing an optical alignment.
Two-dimensional multicolored arrays of quadratic spatial solitons and up-converted parametric amplifications are observed through cascaded non-collinear quadratic processes in quadratic media, which can be switched by phase-insensitive weak beam control with second harmonic seeding pulses.
Small optical third-order nonlinearities of waveguides like hollow-core photonic crystal fibers are characterized using a femtosecond four-wave-mixing scheme. Possible perturbations arising from acoustical and optical phonons are suppressed by low-frequency operation.
We suggest a new efficient method of generation of intense (micro-J) short (fs-ns) THz pulses via coherent scattering of infrared radiation in atomic and molecular gases (f.e. Rb, methanol, and others) at room temperature.
We report the light-assisted poling of controllable periodic and arbitrarily-shaped domain patterns in lithium niobate and lithium tantalate via the simultaneous application of a low uniform DC electric-field and sequence of ultrashort pulses (150-200 fs).
The spectral width of terahertz emission from ion-implanted terahertz emitters increases with ion damage, owing to ultrafast carrier capture. Carrier dynamics simulations reinforce these findings. Optical-pump, terahertz-probe experiments confirm the sub-picosecond lifetimes of these materials.
Optical-pump, terahertz-probe reflection spectroscopy was investigated for the study of femtosecond laser-induced ablation dynamics. The technique can directly measure the quasi-DC complex electrical conductivities of laser-heated solids using non-contact terahertz probe pulses.
We have designed a compact solid compressor by stimulated Brillouin scattering used in a fused silica glass. An 13 ns Nd:YAG laser pulse has been temporally compressed to a 1.2 ns pulse at 1064 nm.
Power scalable approach for THz generation is demonstrated using optical rectification in GaP pumped by a high power ultrafast Yb-doped fiber amplifier. 1.8 muW THz radiation is obtained from 2.6 W pump power.
We fabricate a sub-ps erbium doped fiber laser using a carbon nanotube-polymer composite mode-locker. The spectral and pulse width data are analysed to evaluate the contribution of different physical process into ultra-short lasing.
We demonstrate that microbubbles generated through optical breakdown in tissue phantoms or individual cells are controllable with laser parameters. The controlled microbubbles can be used as an acoustically detectable agent for diagnostic and therapeutic applications.
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