The Photonics Spotlight
Blog articles on topics in photonics, particularly laser technology and application.
- Last build:
- Mon, 05 Mar 2007 12:34:16 +0100
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- More Efficient Frequency Doubling with Shorter Pulses?
For nonlinear frequency conversion of optical pulses, a shorter pulse duration can be beneficial due to the higher peak power. However, other issues can favor longer pulses, and overall the optimum pulse duration or crystal material can strongly depend on the circumstances. The article discusses some of the key issues.
Mon, 5 Mar 2007 12:35:00 +0100 - No Laser, no Result?
This article is a reminder that usefulness in some sense, and not just performance of some hardware, must be the ultimate criterion for judging the quality of paper submissions, e.g. in laser conferences. It can be very misleading just to see whether there is a device with convincing performance, as this alone may not teach us anything interesting and useful.
Mon, 26 Feb 2007 10:35:00 +0100 - Lossy Laser Cavities
It is demonstrated with the example of a simple fiber laser that even severe optical losses within the cavity of a high-gain laser may not have a strong influence on the laser efficiency.
Thu, 22 Feb 2007 17:44:00 +0100 - The Science of Biophotons
The article reports some remarkable research of Prof. Fritz-Albert Popp on biophotons, which leads to mind-boggling new insight into many phenomena.
Fri, 16 Feb 2007 22:06:00 +0100 - Papers Reporting Yet Another Laser Crystal
While the flood of low-quality papers reporting new laser crystals can be tiring indeed, it is clear that good papers in this area should be very welcome even at a time where hundreds of materials are used already. This article identifies some common problems and tries to make constructive suggestions for authoring such papers.
Fri, 9 Feb 2007 12:11:00 +0100 - Continuing Struggle for Larger Fiber Mode Areas
Many papers presented at the conferences Photonics West in San Jose, January 20-25, and Advanced Solid-State Photonics (ASSP) in Vancouver, January 28-31, addressed the issue of larger mode areas of fibers for high power fiber lasers and amplifiers. The article highlights various approaches. So far, it is not clear how far we will get with those.
Sun, 4 Feb 2007 10:48:00 +0100 - Noise Figure of Amplifiers
The article discusses what the noise figure of an amplifier really means, and uses the example of a chain of two high-gain amplifiers. It turns out that an important ingredient of the definition of the noise figure is often overlooked.
Sat, 27 Jan 2007 20:40:00 +0100 - Operation Far Above Threshold
The article discusses various aspects of operating lasers and OPOs far above the pump threshold. It turns out that depending on the situation, quite different effects can come into play, and in most (but not all) cases it is most sensible to operate just a few times above threshold.
Sun, 21 Jan 2007 05:55:00 +0100 - Origins of Heating in Laser Crystals
While heat dissipation and thermal lensing in laser crystals are in principle well known, there are interesting details which are often encountered but not properly understood and handled. The article discusses how heating effects can depend on various parameters, and explains that proper laser designs can avoid a lot of trouble with such matters.
Mon, 15 Jan 2007 10:41:00 +0100 - The Myth of Fiber-Optic Polar Bears
Again and again once encounters the myth the polar bears use fiber optics to stay warm. The article presents some strong arguments against that, and provides further references.
Tue, 9 Jan 2007 18:13:00 +0100 - Why the Encyclopedia of Laser Physics and Technology is Successful
The baffling success of the Encyclopedia of Laser Physics and Technology in terms of search engine ranking, traffic figures and popularity has raised the question how all this was achieved within just over two years. The author explains that the technical content of the encyclopedia is by far of highest importance, while various elements of "white-hat search engine optimization" play some minor role. Essentially the success of the encyclopedia results from hard work, knowledge and experience, and no optimization tricks could ever replace that.
Fri, 5 Jan 2007 11:39:00 +0100 - Peak Position of an Optical Spectrum
This article clarifies an issue which often causes confusion: the maximum of some power spectral density can strongly depend on whether the quantity refers to fixed frequency or wavelength intervals. For this reason, there are differing claims e.g. concerning the wavelength of maximum emission of the sun.
Sun, 31 Dec 2006 16:52:00 +0100 - Dangerous Green Laser Pointers
Here is a safety warning, reporting about cheap green "laser pointers" which emit dangerous levels of optical power in a green beam, sometimes even mixed with infrared light of even higher power. Such a laser product can destroy an eye within a fraction of a second.
Sat, 16 Dec 2006 14:50:00 +0100 - The Laser Industry - High Tech or Low Tech?
It is instructive to think about what really makes high technology and a high-tech industry, and to apply these thoughts to current laser technology. The result is that laser technology certainly share essential aspects of high technology, but what happens on the ground is often not really on that level. Huge potentials in terms of cost and performance are wasted, essentially because the required know-how is not there. Continuing education for the technical staff could solve much of this problem.
Sat, 9 Dec 2006 11:27:00 +0100 - Diffraction in Optical Fibers
A discussion of the role of diffraction in optical fibers, particular in single-mode large mode area fibers, improves the understanding of how such devices work, and illuminates a technological area of intense current interest. An apparently fundamental limit of fibers, related to the too weak effect of diffraction at large mode areas, acts as a road block on the way toward output powers of tens or hundreds of kilowatts from a single fiber.
Sun, 3 Dec 2006 18:44:00 +0100
