Valentin Petrov

Optical, vibrational, thermal, electrical, damage, and phase-matching properties of lithium thioindate

Lithium thioindate (LiInS2) is a new nonlinear chalcogenide biaxial material transparent from 0.4 to 12 μm that has been successfully grown in large sizes and with good optical quality. We report on new physical properties that are relevant for laser and nonlinear optics applications. With respect to AgGaS(e)2 ternary chalcopyrite materials, LiInS2 displays a nearly isotropic thermal expansion behavior, a 5-times-larger thermal conductivity associated with high optical damage thresholds, and an extremely low-intensity-dependent absorption, allowing direct high-power downconversion from the near-IR to the deep mid-IR. Continuous-wave difference-frequency generation (5–11 μm) of Ti:sapphire laser sources is reported for the first time to our knowledge.

Experimental and theoretical study of third-order harmonic generation in carbon nanotubes

Third-harmonic generation from solid samples of carbon nanotubes has been studied experimentally, using ultrashort pulses generated by a Cr:Forsterite laser, at a wavelength of 1250 nm. The results show an unusual nonperturbative behavior of the third-harmonic yield, for relatively low input laser fields, of ∼1010u2002W/cm2. This strong nonlinearity of the laser interaction with carbon nanoubes is also confirmed theoretically, in a full quantum-mechanical theory for harmonics generation from a single-walled carbon nanotube.

Widely tunable continuous-wave mid-infrared laser source based on difference-frequency generation in AgGaS 2

We demonstrate difference-frequency generation in the 6.8-12.5-mum range by mixing two high-power single-frequency laser diodes in a type II AgGaS(2) crystal. This compact all-solid-state scheme provides maximum output powers that exceed 1 muW and permits continuous adjustment-free scans larger than 2 cm(-1) across the entire tuning range.

Femtosecond regenerative amplification in Cr:forsterite

We describe an oscillator-amplifier laser system for the generation of high-power femtosecond pulses near 1.25 microm based on chromium-doped forsterite. Chirped-pulse amplification at a 1-kHz repetition rate raises the pulse energy to >350 microJ. The nearly transform-limited 200-microJ, 135-fs-long recompressed pulses have a peak power of approximately 1.5 GW.

Optical properties of a new nonlinear borate crystal LiRbB4O7

Abstract We present measurements of optical transmission, dispersion and first second-harmonic generation results with the newly discovered nonlinear crystal, LiRbB 4 O 7 . Sellmeier equations are constructed for the 400–700xa0nm spectral range, and the single nonlinear coefficient is estimated to amount to d 14 =0.45xa0pm/V.

Characterization of LiInS2 and LiInSe2 Single Crystals for Nonlinear Optical Applications

Abstract : X-ray structural analysis, nuclear magnetic resonance, optical spectroscopy and second harmonic generation were used to characterize the new nonlinear crystals LiINS2 and LiInSe2 which possess maximum band gap (3.59 and 2.86 eV at 300 K, respectively) among ternary chalcogenides. As grown crystals are only slightly colored while color change after annealing is due to native point defects.

Third-harmonic generation in carbon nanotubes: theory and experiment

The nonlinear optical response of carbon nanotubes (CNTs) to the interaction with intense ultrashort laser pulses was studied theoretically and experimentally. A full quantum-mechanical theory for harmonics generation from a single-walled CNT has been developed, using the quantum kinetic equations for π-electrons with both intraband and interband transitions taken into account. In the regime of strong driving fields, a non-perturbative approach with the numerical solution of the quantum kinetic equations in the time domain was used to calculate the density of the axial electric current in CNTs. The results of this theory are compared to experiments performed on samples of multi-walled CNTs, using pulses of 160 fs generated by a Cr:Forsterite laser, at a wavelength of 1250 nm. The experimental results show indeed an unusual nonperturbative behavior of the third-harmonic yield, for relatively low input laser fields of ~ 1010 W/cm2, in very good agreement with the theoretical predictions. The interaction of CNTs with strong laser fields results not only in the generation of harmonics, but also in the generation of a broad spectral background. Generation of a continuous background in the vicinity of the third-harmonic of the laser field was also obtained from the quantum-mechanical calculations, however, with lower intensities than observed experimentally. Possible explanations for this discrepancy will be discussed.