Photonics West: Monday

23 Jan 2004

Low noise fiber lasers which help to measure wind at airports go on show at Photonics West.

A new range of miniature fiber lasers released at Photonics West 2004 by the Danish firm Koheras are enabling small high-performance LIDAR systems for measuring wind conditions around aircraft.

To date, most compact LIDAR rely on semiconductor lasers but performance is limited by their noise characteristics. “Compared to these, our fiber DFB [distributed feedback] laser typically has several decades better frequency-noise performance and a comparable or even better intensity-noise performance,” said Christian Poulsen, Koheras’ chief technology officer.

The 125x175x75 mm sized module, named PULSIK, emits a train of nanosecond pulses at a single-frequency in the near infrared (selectable between 1535 and 1570 nm). Typical specs include a linewidth of about 1 kHz, a pulse width of 1-10 ns, a repetition rate of 10 kHz and a peak power of 100 W.

As a result, PULSIK laser offers similar optical performance to a Nd:YAG laser but with a footprint and electrical power consumption that rivals a semiconductor source. The key to the fiber laser’s low noise is its DFB design where a fiber grating is used to ensure very stable laser emission that has a very narrow linewidth.

According to Poulsen, the lasers are currently being used at several airports to measure windshear and turbulence. “These have been operating over some time with great success. There is also the potential to equip planes with such LIDAR to give 30 seconds of information on the future wind conditions,” he told Optics.org.

The Copenhagen-based firm has also released a high-power continuous-wave DFB fiber laser which it is also showing at Photonics West. The BOOSTIK module emits up to 5 W of optical power in the near infrared.

Koheras can be found at booth 1442.