Iddo Geltner

Picosecond pulse frequency upshifting by rapid free-carrier creation in ZnSe

The frequency upshifting of 0.8 μm picosecond laser pulses was demonstrated using the temporal change of the free carrier density in a ZnSe semiconductor crystal. The crystal was ionized by transverse propagating ps pulses. Shifts of up to 1.6 nm were observed, which agree within 25% with the theory.

Interferometric measurements of plasma density in microcapillaries and laser sparks

The spatial and temporal evolution of electron density in laser- and discharge-created plasmas in microcapillaries and laser sparks in gases, has been measured by interferometry. The results are compared and the features of these three types of plasmas are summarized from the point of view of x-ray lasers and Raman amplification of ultrashort pulses.

Formation of periodic structures in a laser spark

Periodic plasma density modulations have been observed in a laser spark created by focusing a 5–20 MW laser pulse into nitrogen at 1 to 2 atmospheres. The formation of such structures has been studied by measuring the period as a function of the wavelength λ and the incident angle γ of the laser pulse. The results show good agreement with a surface-instability model. The intensity of the scattered laser light has the same periodicity and is consistent with the measured plasma density profile.

Experimental and Theoretical Simulations for Conditions for Lasing at 13.5 nm in LiIII

We present results related to the search for optimum conditions for lasing to ground state of H‐like LiIII ions at 13.5 nm. These conditions are being considered from the point of view of the development of a prototype of a very compact 13.5 nm laser for metrology of soft x‐ray (EUV) lithography. Theoretical simulations are discussed in relation to experimental data. Experiments on channeling of ultrashort high intensity pumping laser beam in microcapillary plasma are presented for conditions appropriate for lasing at 13.5 nm. We are also discussing Raman amplification of ultrashort pulses in microcapillary plasma as a possibility for future use in X‐ray lasers.

Search For Optimum Conditions For Gain To Ground State In Liiii

The optimum conditions for gain generation for the transition to the ground state at 13.5 nm in Liiii ions were investigated in discharge created pre‐plasma. The spatial and temporal evolution of plasma density was measured and a hollow density profile was observed. Waveguiding of high power laser pulses has been demonstrated in discharge created plasma channels, which can be helpful in increasing the interaction length, thus improving the gain‐length product.

Raman Amplification of Laser Pulses in Microcapillary Plasmas

Raman amplification of ultrashort pulses is demonstrated in microcapillary plasmas. Experiments in very short microcapillaries (0.2 – 0.5 mm) with a broadband seed pulse show that the amplification factor is in agreement with the linear growth rate.