CLEO Europe 2009, laser guide star, and Astrophotonics

On the CLEO Europe 2009 (which was already one month ago!), I presented our recent progresses in developing 589 nm laser for laser guide star adaptive optics. We had coherently beam combined two high power narrow linewidth Raman fiber amplifiers with an efficiency of 95%. After frequency doubling in an external resonant cavity, we have achieved 25 W 589 nm laser with a linewidth less than 2.3 MHz, which is limited by measurement resolution. I have put the slides online: 25 W CW Raman-fiber-amplifier-based 589 nm source for laser guide star.

The conference was intensive and very interesting for me. I noticed many talks and posters on yellow laser generation aiming at laser guide star application. Besides our works, most notable are optically pumped semiconductor lasers, long wavelength Yb fiber lasers, and Bismuth doped fiber lasers. Some new technologies may appear in the coming years, since so many researchers are looking at this direction.

I attended the talk by Prof. Joss Bland-Hawthorn on Astrophotonics. It appears that he had come to my blog and noticed my “concern“. He agreed that laser guide star is an important part of Astrophotonics. 🙂


improved narrow linewidth Raman fiber amplifier

In the past half year, we have improved our narrow linewidth Raman fiber amplifier to 20.7 W and 3.5 MHz linewidth. By external resonant cavity frequency doubling, we have obtained up to 14.5 W CW at 589nm with an optical to optical efficiency of 83% (after an optical isolator and other optics, 17.2 W 1178 nm laser is left to couple to the cavity).

My colleagues will present the work at Photonics West 2009 (LASE 2009, 7195: Fiber Lasers VI: Technology, Systems, and Applications, Post-Deadline Session, Paper 7195-101). Below is the abstract:

20W CW, 4MHz linewidth Raman fiber amplifier with SHG to 589nm

Yan Feng, Luke Taylor, and Domenico Bonaccini Calia
European Southern Observatory, Karl-Schwarzschildstr.2, D-85748 Garching, Germany

Up to 20.7 W CW, 3.5 MHz linewidth, 1178 nm continuous-wave laser has been obtained at ESO laser labs by Raman amplification of a distributed feedback diode laser. The 1178nm laser has a linear polarization-extinction-ratio of 25dB. Frequency doubling with an LBO-based SHG commercial cavity has given 83% conversion efficiency and 14.5W CW at 589nm. The source is suitable to produce mesospheric laser guide stars as reference stars for adaptive optics. The presented narrow-band, high power Raman amplification technique might be used for a large number of different wavelength ranges.

Download the 2-page summary:
Y. Feng, L. Taylor, D. Bonaccini Calia, “20W CW, 4 MHz linewidth Raman fiber amplifier with SHG to 589 nm,” Photonics West 2009, San Jose (postdeadline paper 7195-101).