Passively Q-switched Yb : YAG laser with Cr4+: YAG as the saturable absorber

By using a continuous-wave Ti:sapphire laser as a pumping source, we demonstrated a passively Q-switched Yb:YAG laser at room temperature with Cr4+:YAG as the saturable absorber. We achieved an average output power of as much as 55 mW at 1.03 mum with a pulse width (FWHM) as short as 350 ns. The initial transmission of the Cr4+:YAG has an effect on the pulse duration (FWHM) and the repetition rate of the Yb:YAG passively Q-switched laser. The Yb:YAG crystal can be a most promising passively Q-switched laser crystal for compact, efficient, solid-state lasers. (C) 2001 Optical Society of America.

Temperature dependence of femtosecond laser induced refractive index change in Nd3+-doped phosphate glass

We report refractive index change in a femtosecond laser irradiated Nd3+-doped phosphate glass. The effects of annealing temperature on the refractive index change of the glass have been investigated. Absorption spectra of the glass sample before and after femtosecond laser irradiation and subsequent annealing were measured. The results indicate that multiphoton absorption can undertake although there are intrinsic absorption for the glass in irradiation wavelength. The results may be useful for fabrication of three-dimensional integrated optics devices and waveguide laser devices in this glass. (c) 2004 Elsevier B.V. All rights reserved.

Thermal stress-induced birefringence in borate glass irradiated by femtosecond laser pulses

Thermal stress-induced birefringence in borate glass which has been irradiated by 800-nm femtosecond laser pulses is observed under cross-polarized light. Due to the high temperature and pressure formed in the focal volume, the material at the edge of the micro-modified region is compressed between the expanding region and the unheated one, then stress emerges. Raman spectroscopy is used to investigate the stress distribution in the micro-modified region and indicates the redistributions of density and refractive index by Raman peak shift. We suggest that this technique can develop waveguide polarizers and Fresnel zone plates in integrated optics.

The separation of beta-BBO phase in alpha-BBO crystal by the irradiation of femtosecond laser

We observed and described some phenomena, which were that when a alpha-BBO crystal was irradiated by a focused femtosecond laser beam, the temperature effect happened in a minute area of focus, then the induced beta-BBO phase was separated within the minute area in the alpha-BBO crystal. (C) 2007 Elsevier B.V. All rights reserved.

A novel non-intrusive sampling technique for CO2 laser on-line beam monitoring utilising a silicon mirror

The measurement of high speed laser beam parameters during processing is a topic that has seen growing attention over the last few years as quality assurance places greater demand on the monitoring of the manufacturing process. The targets for any monitoring system is to be non-intrusive, low cost, simple to operate, high speed and capable of operation in process. A new ISO compliant system is presented based on the integration of an imaging plate and camera located behind a proprietary mirror sampling device. The general layout of the device is presented along with the thermal and optical performance of the sampling optic. Diagnostic performance of the system is compared with industry standard devices, demonstrating the high quality high speed data which has been generated using this system.

Thermodynamic damage mechanism of transparent films caused by a low-power laser

A new model for analyzing the laser-induced damage process is provided. In many damage pits, the melted residue can been found. This is evidence of the phase change of materials. Therefore the phase change of materials is incorporated into the mechanical damage mechanism of films. Three sequential stages are discussed: no phase change, liquid phase change, and gas phase change. To study the damage mechanism and process, two kinds of stress have been considered: thermal stress and deformation stress. The former is caused by the temperature gradient and the latter is caused by high-pressure drive deformation. The theory described can determine the size of the damage pit. (c) 2006 Optical Society of America.

Building up a frequency stabilisation based on a wavemeter for a diode laser and characterisation for a digital mirror device for artificial potentials

It has built and characterised a laser and It has learned what each of the components does. It has been able to run the laser in single-mode and stabilised it around a desired setpoint thanks to a PID controller that It has programmed. It has established a communication between the PID controller programmed in LabVIEW and Arduino Due, the DAC that It has chosen after comparing it with another candidate. It has learned some basics of how the LightCrafter 4500 DMD works. The projected light is the composition of the lights of three LED’s, each of which has a certain on-time. The mirrors chose to be in on- or off-stages depending to the amount of intensity that we want for each colour.