In the current issue of Optics Express, there is a focus issue on Astrophotonics. The coordinators, Joss Bland-Hawthorn and Pierre Kern, have an introductory paper, Astrophotonics: a new era for astronomical instruments. The abstract is

Astrophotonics lies at the interface of astronomy and photonics. This burgeoning field has emerged over the past decade in response to the increasing demands of astronomical instrumentation. Early successes include: (i) planar waveguides to combine signals from widely spaced telescopes in stellar interferometry; (ii) frequency combs for ultra-high precision spectroscopy to detect planets around nearby stars; (iii) ultra-broadband fibre Bragg gratings to suppress unwanted background; (iv) photonic lanterns that allow single-mode behaviour within a multimode fibre; (v) planar waveguides to miniaturize astronomical spectrographs; (vi) large mode area fibres to generate artificial stars in the upper atmosphere for adaptive optics correction; (vii) liquid crystal polymers in optical vortex coronographs and adaptive optics systems. Astrophotonics, a field that has already created new photonic capabilities, is now extending its reach down to the Rayleigh scattering limit at ultraviolet wavelengths, and out to mid infrared wavelengths beyond 2500nm.

I think laser guide star should be an important part of Astrophotonics. They mentioned in (vi), but didn't mention in the main text at all. Also I don't understand why large mode area fibers are the key to generate artificial stars.

It is a very interesting issue for me, although laser guide star is suprisingly absent.

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).

Poor man's laser

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

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

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.

Active galactic nuclei with laser guide star adaptive optics

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

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.

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.

OSA Podcast: Enhancing Your Career in Optics

An update from OSA Podcast, on career in Optics. Worth listening.

First Laser

May 16, 2008. Above is today's Google logo.

The first working laser was demonstrated on May 16, 1960 by Theodore Maiman at Hughes Research Laboratories.

According to Wikipedia.