High gain and high peak power in planar waveguide lasers
We report enhanced peak power and gain for pulses in the 10-100 /spl mu/sec range, with specific peak power to 240 kW m/sup -2/ of electrode area at frequencies to 4 kHz. Pulsed small signal gain is increased by a factor of 7 relative to cw/long pulse excitation.
Enhanced peak power CO2 laser processing of PCB materials
Laser drilling has become a common processing step in the fabrication of printed circuit boards (PCB's). For this work, a recently developed enhanced peak power CO2 laser (~2.5 kW peak power, 200W average) or ultra-super pulse (USP) laser is used to drill alumina and copper coated dielectric laminate materials. The higher peak power and faster response times (than conventional CO2 lasers) produced by the USP laser are used to produce high speed alumina laser scribing and copper coated laminate microvia drilling processes. Alumina is a common PCB material used for applications, where its resistance to mechanical and thermal stresses is required. Here we present a comprehensive study of the melt eject mechanisms and recast formation to optimise the speed and quality of alumina laser scribing. Scribe speeds of up to 320 mms-1 (1.8 times current scribe rate) have been achieved using novel temporal pulse shapes unique to the USP laser. Also presented is the microvia drilling process of copper dielectric laminates, where the multi-level configuration presents different optical and thermal properties complicating their simultaneous laser ablation. In our experiments the USP laser has been used to drill standard thickness copper films (up to 50 μm thick) in a single shot. This investigation concentrates on understanding the mechanisms that determine the dielectric undercut dimensions.
Slab waveguide high-power pulsed rf-excited CO2 laser
Slab RF-excited pulsed CO2-laser with the pumping frequency F equals 152 MHz, pulse duration in the range of 20 divided by 50 microsecond(s) , and pulse repetition rate f up to 100 Hz has been investigated. Output power, temporal shape of laser pulses, laser beam divergence were measured at the pumping power up to 400 W/cm3. Pulsed output power was varied in the range of 2 divided by 5 kW. The package of numerical simulation codes of pulse-repetition mode of slab CO2 laser was created. It is shown that the maximum input power is significantly increased by the change of excitation frequency from 80 up to 150 MHz. The measured and numerical data are compared.