THz Repetition Rate Research Articles

Dynamic temporal pulse shaping in advanced ultrafast laser material processing

Phase-manipulated ultrafast laser pulses and temporally tailored pulse trains with THz repetition rates are promising new tools for quality micromachining of brittle dielectrics, allowing to adapt the laser energy delivery rate to the material properties for optimal processing. Different materials respond with specific reaction pathways to the sudden energy input depending on the efficiency of electron generation and on the ability to release the energy into the lattice. The sequential energy delivery with judiciously chosen pulse trains may induce softening of the material during the initial steps of excitation and change the energy coupling for the subsequent steps. We show that this can result in lower stress, cleaner structures, and allow for a material-dependent optimization process.

Optical creation of vibrational intrinsic localized modes in anharmonic lattices with realistic interatomic potentials

Using an efficient optimal control scheme to determine the exciting fields, we theoretically demonstrate the optical creation of vibrational intrinsic localized modes (ILM's) in anharmonic perfect lattices with realistic interatomic potentials. For systems with finite size, we show that ILM's can be excited directly by applying a sequence of femtosecond visible laser pulses at THz repetition rates. For periodic lattices, ILM's can be created indirectly via decay of an unstable extended lattice mode which is excited optically either by a sequence of pulses as described above or by a single picosecond far-infrared laser pulse with linearly chirped frequency. In light of recent advances in experimental laser-pulse shaping capabilities, the approach is experimentally promising.

Optical pulse synthesis with three cw semiconductor lasers using nonlinear phase-locking

Optical pulse synthesis is demonstrated by superposition of equidistant frequencies from separate single-frequency AlGaAs semiconductor lasers which are phase-synchronized by a nonlinear phase-locking scheme. This is done by phase-locking the second harmonic of a laser frequency to the sum frequency of the other two lasers using homodyne detection. Well-defined optical pulses are generated in both the fundamental infrared and the blue light regions. The pulse synthesis principle is examined with relatively small frequency separations of up to several hundred MHz. This method can be easily extended to extremely wide frequency separations, which results in ultra-short optical pulses with more than THz repetition rates.

Generation of 5 THz repetition optical pulses by modulation instability in optical fibers

5 THz repetition rate optical pulses have been achieved with modulation instability in an optical fiber. The detailed investigation on the relationship between fiber anomalous dispersion and modulation frequency enables high repetition rate optical pulses, yielding a control method of pulse repetition rate.

Generation of 2 THz repetition rate pulse trains through induced modulational instability

Trains of 130 fs pulses at 2 THz repetition rates have been generated through induced modulational instability in a single-mode fibre from an anti-Stokes CW diode laser signal on a carrier frequency provided by a mode-locked Nd:YAG laser

Generation of subpicosecond solitonlike optical pulses at 0.3 THz repetition rate by induced modulational instability

We report the generation of 0.5 ps full width at half-maximum optical pulses at >0.3 THz (tunable) repetition rate via an induced modulational instability in a single-mode fiber. A 1.319-μm neodymium:yttrium aluminum garnet laser is chosen as the carrier wave and the initial modulation on this carrier is introduced by mixing it with an external-grating-cavity InGaAsP laser. The use of this all-optical modulating scheme and the nonlinear optical propagation effect in fiber (i.e., modulational instability) allows one to reach into the terahertz regime, which is about two orders of magnitude beyond the fastest data limited by the finite response of electronics.