Canunda-Pulse | Ultrafast Laser Beam Shaper

• Stabilizing ultrashort lasers: CANUNDA-PULSE Mode-Cleaner boosts the stability of femtosecond laser processes

Precision is critical for many of today’s industries, including watchmaking, luxury goods, smartphones, electronics and solar panels. High-precision manufacturing on an industrial scale presents a major challenge, not just for today’s technology, but also for future innovations. That is why lasers, and in particular ultrashort pulse lasers (picoseconds and femtoseconds), have become an essential manufacturing tool. They perform cutting, engraving and welding operations with unparalleled precision and detail (on a micrometer or even nanometer scale).

However, this degree of precision requires lasers to be as stable as possible. A laser source is a complex photonic system composed of multiple components (mirrors, lenses, amplifying medium, electronics, etc.) which are subjected to various forms of turbulence during operation. This results in an “unstable” laser beam output that is subject to various fluctuations: beam tilt, beam shift, defocusing, diameter variations, etc.

The main causes of laser beam fluctuations are:

1. Mechanical vibrations, transmitted from the ground or caused by shocks, which can affect the alignment of the optical elements inside the laser source.⁽¹⁾ 
2. Thermal effects in the amplifying medium (caused by changes in operating parameters, or simply by heating during use), which can induce defocusing or deflection of the laser beam.^{(1, 2)} 

This type of beam instability can cause significant problems in a laser system. For example, it can lead to manufacturing inaccuracies in micromachining applications due to variations in the shape and position of the incoming beam on the material to be machined. For laser detection applications, it can result in measurement inaccuracies. Such instability can even cause damage, for example when a high-energy femtosecond beam is coupled to a hollow-core fiber, which can be damaged if the beam is not precisely injected into it. Finally, if a beam shaping system is also used, these instabilities can lead to beam distortion, resulting in a loss of machining quality.

To ensure laser beam stability, Cailabs has developed an innovative solution: CANUNDA-PULSE Mode-Cleaner. It is a passive stabilization module specifically designed for ultrashort pulse lasers which “absorbs” the various instabilities of a laser beam (tilt, shift, defocus, etc.).

Integrated at the laser source output, the MPLC technology developed by Cailabs decomposes the laser beam into several components:  

1. The TEM00 or fundamental mode laser, corresponding to a Gaussian beam as it would be produced by a perfect laser source.
2. Other “parasitic” modes, corresponding to laser imperfections (tilt, shift, defocus, etc.). 

By instantly suppressing the parasitic modes and keeping only the fundamental mode, it generates a perfectly stable beam, even with strong fluctuations of the laser source due to intensive use, vibrations or shocks. CANUNDA-PULSE Mode-Cleaner can be easily integrated into an existing laser system, making it the ideal solution for boosting the stability of your laser. 

The Mode-Cleaner functionality is also included in all CANUNDA-PULSE top-hat modules. 

• Thin film laser ablation: Canunda improves the quality and efficiency of thin film laser ablation processes.

Thin film patterning, also called decoating, is the selective ablation of one or more layers from a material substrate. This process is usually performed by ultrashort (typically femtosecond) lasers. This laser process is athermal. The material is sublimated using ultra-high peak power pulses.  

The use of ultrashort lasers not only allows the ablation of extremely narrow track widths (in the micrometer range), it also enables the extremely precise control of ablation depth. As the ablation depth per pulse is generally less than the final depth required, the laser must move several times over the same area. Finally, the athermal process does not damage the underlying layers (substrate) of the ablated layers surrounding the machined area, thus preserving their properties.  

This process is mainly used for photovoltaic panels, OLED panels, and electronics.  

The challenges of thin film patterning are the process efficiency and track quality, especially in terms of conicity.

Improved thin film ablation process quality using ultrashort pulsed lasers with CANUNDA-PULSE by reducing the track conicity. CANUNDA-PULSE enables the shaping of an ultra-narrow top-hat beam in the machining plane (ranging from a few micrometers to a few tens of micrometers) with particularly narrow transition zones (up to 17 times narrower than a traditional Gaussian beam) in order to provide high-speed taper-free drilling. CANUNDA-PULSE products can be easily integrated into micromachining equipment. 

• Laser drilling: Improve the quality and efficiency of laser drilling processes

Laser drilling consists of removing material to create a partial or a fully drilled hole. Micro-drilling is usually performed by ultrashort (typically femtosecond) lasers. This laser process is athermal. The material is sublimated using ultra-high peak power pulses. The drilled parts can be all types of materials — metals, ceramics, polymers, etc. 

There are many methods of drilling materials:

1. Percussion drilling: this involves applying repeated laser pulses to the same place until the desired thickness has been ablated. The resulting hole is slightly larger than the laser spot.  
2. Spiral drilling: this involves making multiple successive spirals from the center to the edge of the hole until the desired hole width has been achieved. The resulting hole can be much larger than the laser spot. Trepanning and precession drilling are similar techniques, with different beam angles.
3. Contour drilling: this involves moving the laser around the perimeter of the hole to be drilled several times until the central part becomes detached. This type of drilling creates a through hole.  

The first industrial application of femtosecond lasers was to produce fuel injectors for the automotive industry, where extremely small holes needed to be drilled to optimize engine efficiency. Drilling processes are also used in the electronics sector to produce boards and to insert ever smaller components into them with extreme accuracy.  

Today’s drilling processes face two challenges: improving process efficiency and drilling fast, taper-free holes.  

Improved cutting process quality using ultrashort pulsed lasers with CANUNDA-PULSE by reducing the drilling conicity. CANUNDA-PULSE enables the shaping of an ultra-narrow top-hat beam in the machining plane (ranging from a few micrometers to a few tens of micrometers) with particularly narrow transition zones (up to 17 times narrower than a traditional Gaussian beam) in order to provide high-speed taper-free drilling. CANUNDA-PULSE products can be easily integrated into micromachining equipment.