Fourier transform with matched non-linear frequency modulation in femtosecond laser ranging with imbalanced dispersion.

We propose a new algorithm based on the Fourier transform with matched non-linear frequency modulation for processing femtosecond laser ranging data. The algorithm allows us to compensate for both the influence of the third-order dispersion in the fiber-based dispersive Fourier spectrometer and the influence of imbalanced second- and third-order dispersions in the interferometer. Computer simulations and experimental results show that the proposed algorithm significantly increases the accuracy of measuring the position of an object at larger displacements than the well-established non-linear time stretching.

NV diamond laser.

For the first time, lasing at NV centers in an optically pumped diamond sample is achieved. A nanosecond train of 150-ps 532-nm laser pulses was used to pump the sample. The lasing pulses have central wavelength at 720 nm with a spectrum width of 20 nm, 1-ns duration and total energy around 10 nJ.

Total internal reflection of the mid-IR near single-cycle light bullet in LiF.

Mid-IR light bullets formation and self-reconstruction after total internal reflection in LiF is investigated experimentally and through numerical simulations. The experiment showed that spatial-temporal deformations of the wave packet in inhomogeneous wave on a reflecting interface can be neglected for this process and a near single-cycle light bullet can be formed or recovered after a distance determined by its energy loss for ionization and supercontinuum radiation. The estimation of the reconstruction distance by an empirical formula for self-focusing distance on the base of the peak power and the radius of the LB numerical simulation are in a good agreement with experimental data received.

Mid-infrared single-cycle light bullet self-reconstruction after an air gap under single-pulse femtosecond filamentation in LiF.

We have studied the penetration of the extremely compressed wave packet-"light bullet" (LB)-through an air gap upon femtosecond single-pulse mid-IR filamentation in LiF. Applying the laser coloration method and performing numerical simulations, we have found that the single-cycle LB, which is formed before the air gap up to 0.5 mm wide, completely recovers after passing a certain distance inside LiF after the gap.

Giantically blue-shifted visible light in femtosecond mid-IR filament in fluorides.

A giant blue shift (more than 3000 nm) of an isolated visible band of supercontinuum was discovered and studied in the single filament regime of Mid-IR femtosecond laser pulse at powers slightly exceeding critical power for self-focusing in fluorides. At the pulse central wavelength increasing from 3000 nm to 3800 nm the spectral maximum of the visible band is shifted from 570 nm and 520 nm up to 400 nm and 330 nm for BaF(2) and CaF(2), respectively, its spectral width (FWHM) being reduced from 50 - 70 nm to 14 nm. It is shown that the formation of this narrow visible wing is a result of the interference of the supercontinuum components in the anomalous group velocity dispersion regime.