Search

A study of the photosensitivity of lead germanate glasses grown by pulsed laser deposition is presented. Lead germanate films were grown from stoichiometric bulk targets, on borosilicate glass substrates in an oxygen atmosphere, to form optical waveguides. The films grown exhibited high absorption in the ultra violet spectral area (around 240 nm) which indicated the possibility of high photosensitivity. The photosensitivity of the materials was examined by phase mask and interferometric grating recording over a wide ultra violet spectral region (325nm-193nm) using various continuous and pulsed laser sources. Very high refractive index changes (up to 1%) have been observed along with variable sign of the refractive index change depending on the oxygen background pressure used during growth and recording intensity

Lead germanate thin films have been grown on BK7 and silica substrates, using pulsed excimer laser deposition (PLD) at wavelengths of 193 and 248 nm, from a bulk lead germanate target under various partial pressures of oxygen. The films produced vary in colour from brown, through clear, to yellow, and a parametric study has been undertaken of the film properties as a function of the growth conditions. The measured losses of the lead germanate films grown on glass substrates varied from ~ 2.5 to 7 dB /cm depending on the oxygen partial pressure used.

Description Edited by major contributors to the field, this text summarizes current or newly emerging pulsed laser deposition application areas. It spans the field of optical devices, electronic materials, sensors and actuators, biomaterials, and organic polymers. Every scientist, technologist and development engineer who has a need to grow and pattern, to apply and use thin film materials will regard this book as a must-have resource.

Here we analyze the achievable resolution for a single interface deflector. It can be seen that with a suitably sized device, significant resolution can be attained from a single interface deflector. This would be the first ever report to our knowledge of a 2D EO solid state beam deflector.

We discuss the maximum theoretical resolution of a single interface, electro-optically controllable beam deflector in domain-engineered LiNbO3 and report on experimental results for implementation of devices optimized either for maximum resolution or for maximum deflection angle. For the resolution optimized device we observed approximately 50 resolvable spots for a +/- 1250-V range, which to our knowledge is a report of one of the highest ratios of resolution per volt from a solid-state electro-optic beam deflector.

Summary from only given. Self adaptive laser resonators based on laser induced gain gratings have successfully demonstrated correction of thermally induced aberrations in solid-state lasers. This technique has recently been shown to produce distortion corrected beams in a diode pumped, injected seeded system in Nd:YVO/sub 4/. This paper describes the first characterization of a fully self-starting, high power Nd:YVO/sub 4/ self adaptive laser without the requirement of an external seed source.

Summary from only given. Self-adaptive gain grating lasers have previously been demonstrated that can actively correct for thermally induced phase distortions. Here we discuss the power-scaling of such a resonator which operates at 6 W in its basic form. Our first attempts using a power amplifier in the output arm have lead to almost 12 W of single longitudinal mode output with a beam quality of M/sup 2/ = 1.3.

We demonstrate a power-scaling strategy in a continuous-wave adaptive phase-conjugate oscillator power amplifier (PCO-PA) system that actively corrects, via phase-conjugation, for thermally induced phase-distortions introduced by a power-amplifier (PA) placed in the output arm of the phase conjugate oscillator (PCO). Phase-conjugation is achieved by saturable gain four-wave mixing in a PCO Nd:YVO4 amplifier. Single-longitudinal mode phase-conjugate (PC) outputs of almost 11.5 W with an Mx2=1.4, My2=1.2 have so far been achieved with a PCO operating at 6 W PC output, a power gain of two through the PA. The saturable gain four-wave mixing that takes place in the PCO-PA system has been modelled and the results can be used to predict how best to proceed with further increasing the PC output power from such a system.

Summary form only given. Pulsed laser deposition (PLD) has always been a potentially attractive method of fabricating waveguides due to low running and capital costs. The ability to quickly and easily grow stochiometric, epitaxial films of a large variety 15 of laser media makes it an almost ideal fabrication process. PLD has been avoided as a preferred method, however, due to the large number of particulates generated on the waveguides during growth. There has been no direct correlation however, between the number of particulates seen on the films and the losses generated. In this paper we report on the comparison between losses observed in a waveguide and particulate density. We shall also report the performance of a buried waveguide structure, in which the effects of particulates should prove less important. Using similar to conditions to those reported earlier, we have grown films of epitaxial [100] Nd:GdGG on a [100] YAG substrate.

Photosensitivity in (predominantly) germanium doped fibres and planar waveguide structures is the subject of intense current interest. Permanent refractive index gratings, written using UV light from either pulsed or C.W. laser sources, can be produced by interferometric exposure, yielding Δ(n) values ranging from 10-5 to 10-3. Additional techniques such as hydrogen loading, or flame brushing, can further increase this value to ~10-2.In this paper, we report our studies of planar waveguides of lead germanate glass, grown by Pulsed Laser Deposition. The films are grown under various partial pressures of oxygen, and show distinct and systematic differences in colour, waveguide loss and photosensitivity. We interpret our results in the context of induced oxygen vacancies produced during the growth.

A recently proposed alternative to conventional prism-type electro-optic solid-state deflectors is the single interface deflector. Whereas these deflectors are comparable in performance to prism-type deflectors, they are far simpler in construction. This simplicity obviously has the advantages that it reduces fabrication time and cost and allows for easier optimization. Less obviously, but more advantageously, the simplified geometry provides, for the first time to our knowledge, the ability to achieve a completely solid-state two-dimensional beam deflector. We also detail how the two-dimensional deflector can be further augmented by the addition of intensity and color switching to the device.