Femtosecond Yb:KGW MOPA driven broadband NOPA as a frontend for TW few-cycle pulse systems.

White light continuum seeded noncollinear optical parametric amplifier driven by Yb:KGW master oscillator power amplifier (MOPA) system is reported. The demonstrated design provides amplification of broadband pulses at 800 nm up to 20 µJ energy at 1 kHz repetition rate and can be used as simple and reliable frontend source for systems producing high intensity few-cycle pulses. The amplified spectral bandwidth allows for <7 fs pulse durations and preliminary compression of partial spectrum yields sub-10 fs pulse.

Optical parametric oscillator pumped by a Bessel beam.

We demonstrate operation of a KTP optical parametric oscillator (OPO) pumped by a Bessel beam for the first time to our knowledge. It is shown that the output of the OPO has a transverse profile, which is consistent with noncollinear phase-matching relations defined by a conical pump. The central spot and ring related to the pair of signal and idler beams were generated in the OPO. By adjusting the OPO cavity mirrors, we easily selected the lowest-order mode as well as the higher-order transverse modes in the central spot. Bessel beam pumping was shown to be useful, providing tubular beam coupling into OPO cavity modes. The OPO threshold pump energy was ~100 muJ in a 6-ns pulse.

[Effects of light-activated hematoporphyrin derivative on nucleotides and experimental tumors]. / Vozdeistvie aktivirovannogo svetom proizvodnogo gematoporfirina na nukleotidy i éksperimental'nye opukholi.

The data on the photodamage of biomolecules and experimental tumours by a hematoporphyrin derivative activated with laser radiation are presented. Inhibition of the tumour growth and prolongation of the life-span of treated tumour-bearing animals are observed.