New ultrashort pulse laser source for nano-materials processing

Experimental setup of the femtosecond laser. Blue light is emitted from the new pump diodes. (Image: B. Resan, FHNW)

In the Nano Argovia project NanoLase, a team from the School of Engineering (FHNW), the Paul Scherrer Institute and the company TLD Photonics AG (Wettingen, AG) is developing a novel laser source that generates ultrashort pulses. The new device is expected to be more cost-effective, reliable and compact compared with existing laser systems. It will also generate several times shorter pulses compared with current industrial lasers enabling transition from laser micromachining to laser nanomachining. In addition to industrial materials processing, such a laser source would be very beneficial in life sciences and numerous other scientific applications.

Different parameters
Today, lasers are used to process a variety of materials. The wavelength, average power, pulse energy and pulse duration of the laser are parameters that must be adapted to the particular material and project and are decisive for the result of the processing. How much the material heats up and degrades the quality of the microstructure, and the amount of material removed by the laser in the process, are determined primarily by the duration of the laser pulse and the irradiance.

If heat generation is to be reduced to a very small zone (heat-affected zone < 1 micrometer) when processing with a laser, pulses of extremely short duration of less than 100 femtoseconds (1 femtosecond = 10-15 seconds) are required. Until now, this was only possible using scientific laser setups in the scientific labs and low power. This leads to results that are not reproducible and long processing times that are not acceptable for industrial applications.

Shorter pulses
In the Nano Argovia project NanoLase, the teams of project leader Professor Bojan Resan (FHNW), Dr. Alexandre Trisorio (PSI) together with industry partner Stephan von Wolff (TLD Photonics AG) are pursuing a new approach that allows higher precision processing due to shorter pulses, for polymers and glass with lasers with emission wavelength in the infrared range, and for metals with the laser wavelength converted to the UV region.

The researchers aim to achieve this by developing a laser amplifier made of titanium-doped sapphire with a new single-crystal geometry (SCF). The SCF geometry enables manifold increase in the average laser output power due to higher efficiency cooling. In addition, the scientists will use novel low-cost blue laser diodes with a wavelength of 445 nanometers (mass produced for displays and the car industry) to pump titanium-doped sapphire lasers, which will make the lasers compact, low cost and industrial grade.

The results of this project are expected to address the current lack of compact, low-cost and reliable lasers that produce high power and ultrashort pulses suitable for industrial micro- and nano-machining.

“The NanoLase project is very exciting and promising for TLD Photonics as it helps to develop new technology, as well as to demonstrate its use in materials processing. It will bring the new product line to TLD Photonics, which could represent a breakthrough from laser micro- to laser nano-machining.”

Quote Stephan von Wolff, CEO of TLD Photonics AG

Additional information

TLD Photonics
School of Engineering (FHNW)
Paul Scherrer Institute