Terahertz generation in Czochralski grown periodically poled Mg:Y:LiNbO3 via optical rectification

Using a canonical pump-probe experimental technique, we studied the terahertz (THz) waves generation and detection via optical rectification and mixing in Czochralski-grown periodically poled Mg:Y:LiNbO3 (PPLN) crystals. THz waves with frequencies at 1.37 THz and 0.68 THz as well as 1.8 THz were obtained for PPLN with nonlinear grating periods of 0.03 and 0.06 mm, respectively. A general theoretical model was developed by considering the dispersion and damping of low frequency phonon-polariton mode. Our results show that THz waves are generated in forward and backward directions via pumping pulse rectification. The generated THz waves depend on the spectral shape of the laser pulses, quasi-phase mismatches and dispersion characteristics of a crystal.Comment: 25 pages, 4 figure

On negative higher-order Kerr effect and filamentation

As a contribution to the ongoing controversy about the role of higher-order Kerr effect (HOKE) in laser filamentation, we first provide thorough details about the protocol that has been employed to infer the HOKE indices from the experiment. Next, we discuss potential sources of artifact in the experimental measurements of these terms and show that neither the value of the observed birefringence, nor its inversion, nor the intensity at which it is observed, appear to be flawed. Furthermore, we argue that, independently on our values, the principle of including HOKE is straightforward. Due to the different temporal and spectral dynamics, the respective efficiency of defocusing by the plasma and by the HOKE is expected to depend substantially on both incident wavelength and pulse duration. The discussion should therefore focus on defining the conditions where each filamentation regime dominates.Comment: 22 pages, 11 figures. Submitted to Laser physics as proceedings of the Laser Physics 2010 conferenc

Reduction of optical nonlinearities of Ga-La-S glasses for active fibre applications through addition of CsCl

Measurements of the optical nonlinearities of halide modified GaLa sulphide glasses near 1.3µm are reported. The addition of CsCl to the glass matrix reduces the intensity-dependent index of refraction by up to an order of magnitude, making these glasses better candidates for fibre amplifiers than pure Ga-La sulphide glass

Next generation access networks: PIEMAN and beyond

Long-reach access networks such as the hybrid TDM-WDM-PON studied in the EU-funded project PIEMAN reduce node count and increase bandwidth per customer, but require challenging opto-electronic component development. We review PIEMAN's achievements and future possibilities

Next generation access networks: PIEMAN and beyond

Long-reach access networks such as the hybrid TDM-WDM-PON studied in the EU-funded project PIEMAN reduce node count and increase bandwidth per customer, but require challenging opto-electronic component development. We review PIEMAN's achievements and future possibilities