Yan Feng -

Poor man's laser

yan — Thu, 06 Nov 2008 20:06:11 +0000

Two published poor man's lasers:

1. Poor man’s source for sub 7 fs: a simple route to ultrashort laser pulses and their full characterization.
2. Poor Man's Channel Waveguide Laser: KY(WO4)2:Yb.

I may add a paper to the list later. :)

Solar pumped laser reaches 80W

yan — Thu, 23 Oct 2008 14:56:53 +0000

A new report from Prof. Takashi Yabe: 100 W-class solar pumped laser for sustainable magnesium-hydrogen energy cycle, J. Appl. Phys. 104, 083104 (2008). They used a Fresnel lens (2×2 m, f=2000 mm) for collecting solar radiation, a Cr:Nd: YAG ceramic rod as gain medium, and get 80 W maximum laser power, corresponding to a 4.3% net conversion from solar light. That's really a cool result.

I always say to my colleagues that solar pumped laser is my dream research project, because then I can do experiments under sunshine instead of in a basement lab. ;)

Dr. Rüdiger Paschotta's books

yan — Mon, 20 Oct 2008 19:14:11 +0000

Dr. Rüdiger Paschotta, who runs a consulting company after a successful academic career, just published another book: SPIE Field Guide to Laser Pulse Generation. His first book is SPIE Field Guide to Lasers.

Encyclopedia of Laser Physics and Technology, his notable and useful web project, also has a print version now.

He leads a very interesting career.

Why do all three taikonauts of Shenzhou 7 are 42 years old?

yan — Fri, 26 Sep 2008 07:39:12 +0000

Because 42 is the Answer to Life, the Universe, and Everything.

Shenzhou 7

The engineering of Science

yan — Sun, 17 Aug 2008 10:55:44 +0000

Science 2.0 is all about better way of Science practice in new time. A new academic discipline of Science Engineering is emerging?!

This is what came to my mind, when I saw Michael Nielsen resigned from Perimeter Institute for pursuing his new interests in the development of new tools for scientific collaboration and publication.

Active galactic nuclei with laser guide star adaptive optics

yan — Wed, 16 Jul 2008 15:10:32 +0000

I found this presentation on Google Video: Active galactic nuclei with laser guide star adaptive optics. It is from the AAS 212th Meeting. The presenter is Claire Max.

Adaptive optics on the current generation of 8 - 10 meter telescopes yields spatial resolutions in the near-infrared comparable to those of Hubble at visible wavelengths. Laser guide stars are now making these high spatial resolutions available over a large fraction of the sky. I will describe several areas in which these advances are being applied to AGN science: 1) measurement of black hole masses in nearby galaxies from kinematics of stars and gas; 2) study of the spatial distribution of stellar populations and dust in galaxies at 0.5 < z < 1.5, and 3) tests of the relationship between galaxy mergers and AGN activity. I will conclude with a discussion of the planned Next Generation Adaptive Optics system at the W. M. Keck Observatory, outlining the expected improvements in AGN science with this new system.

A timelapse of the Paranal laser guide star

yan — Wed, 16 Jul 2008 14:54:10 +0000

The authors of the time lapse movie are Stéphane Guisard, Valère Leroy and Jean Pajus. It is fun to see the PARSEC laser pointing to different directions of the universe over the night. I wonder what the night sky would look like in Hawaii, where there are several guide star lasers.

This is a time lapse movie made from individual images taken with a Canon 20Da camera and a 8mm lens. This accelerated movie shows a complete night at Paranal Observatory starting at sunset and finishing at dawn. That night, the Laser Guide Star Facility was in use and its yellow sodium Laser beam left its footprint on our movie. The laser beam creates a Laser Guide Star in the high atmosphere, 90 km above us. This 'bright' artificial star helps the adaptive optics system located in the main telescope, to measure and correct the distorsions of the images produced by the atmosphere, in real time and several hundreds of times per second.

The bright part of the Milky Way, containing the galactic center, is disappearing to the west on the left hand side of the movie. The Andromeda galaxy is visible also, as a diffused and elongated spot crossing the sky just above the domes. One can also see the Pleiades and "upside down" Orion constellation rising (remember this movie is done from the Southern hemisphere) together with the other half of our Milky Way . Finally the moon lightens the morning sky just before sunrise.

Narrow linewidth laser with fiber Raman amplification

yan — Thu, 10 Jul 2008 20:15:09 +0000

We have a new publication online now: multiwatts narrow linewidth fiber Raman amplifiers. Basically, the paper shows fiber Raman amplifier can be used to amplify narrow linewidth laser to a useful power level, while linewidth keeping narrow. This would be a surprise to most laser researchers. In this specific report, we have obtained 4.8 W, ~10MHz 1178nm laser with 27dB gain and more than 10% efficiency. The tricks and reason are explained in the paper.

2007 Journal impact factors

yan — Thu, 03 Jul 2008 20:52:34 +0000

Files containing journal impact factors for 2007 can be downloaded here or here.

The Lindau Nobel Laureate Meetings

yan — Thu, 03 Jul 2008 20:47:39 +0000

Waw, there is a big event in Lindau, not far away from me.

The Lindau Nobel Laureate Meetings provide a globally recognised forum for the transfer of knowledge between generations of scientists. They inspire and motivate Nobel Laureates and international Best Talents. Lectures of Nobel Laureates reflect current scientific topics and present relevant fields of research of the future. In panel discussions, seminars and during the various events of the social programme young researchers nominated by a worldwide network of Academic Partners interact with Nobel Laureates.