High power ultrafast lasers and thermal lensing

High power ultrafast lasers have a great diversity of applications thanks to their short pulse durations and high peak powers. 

Ultrafast lasers are applied in materials processing applications, medical fiber lasers, microscopy, etc. All the fiber lasers‘ advantages provide them with higher powers. However, fiber laser technology is particularly sensitive to the effects such as thermal lensing.

Thermal lensing is a process occurring in ultrafast laser gain media, especially for operation at higher power levels. It crucially limits the laser beam quality and the output power. These processes decline the ultrafast lasers‘ performance and can also cause an absence of the mode-lock and producing pulses. For high power ultrafast lasers, thermal lensing can even result in the whole system crashing. Besides, thermal lensing results in astigmatism in ultrafast laser cavities. Ultrafast lasers work in continuous-wave (CW) mode for cavity alignment. And then the ultrafast lasers switch to a pulsed configuration for actual use. But thermal lensing may disrupt the work of the ultrafast laser system.

The impossibility to apply pulsed laser beams makes ultrafast lasers ineffective. However, there are a few available options that can help in manipulating the inherent thermal properties of gain media and preventing thermal lensing. One of them is choosing the proper dispersive mirror coatings.

With the help of highly dispersive intracavity mirror coatings, scientists have an opportunity to minimize the effect of thermal lensing. Thanks to these achievements, they could produce better high power ultrafast lasers where there are intracavity optics with negligible thermal effects. These ultrafast laser systems are useful for both external optics and outside of the ultrafast laser cavity. The thermal lensing-limiting technology can supervise the laser beam stability and pulse compression whereas detrimental thermal effects are minimized.

Scientists could develop highly dispersive ultrafast mirrors for ultrafast lasers. These mirrors can maintain high reflectiveness and desirable pulse compression while providing negligible thermal effects. Such characteristics are achieved by careful management of the different processes during coating deposition.

However, several ultrafast laser systems don’t require this newly developed technology. Several lasers don’t have a high average power for thermal lensing to occur. So it isn’t a significant issue for them. Some fiber laser systems don’t include a solid-state lasing cavity where thermal effects may have a place. Nevertheless, there are solid-state high power ultrafast lasers where low thermal lensing is crucial.

Optromix Inc., headquartered in Cambridge, MA, USA, is a manufacturer of laser technologies, optical fiber sensors, and optical monitoring systems. We develop and manufacture a broad variety of Fiber lasers, СО 2 lasers, Ti: Sapphire lasers, Dye lasers, and Excimer Lasers. We offer simple Erbium laser and Ytterbium laser products, as well as sophisticated laser systems with unique characteristics, based on the client’s inquiry.

We manufacture laser modules using our technologies based on the advanced research work and patents of the international R&D team. Laser processes are high-quality, high-precision, easily automated manufacturing solutions that provide repeatability and flexibility.

If you are interested in Optromix fiber laser systems or Optromix CO2 lasers, please contact us at info@optromix.com

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