Blog articles on topics in photonics, particularly laser technology and application. http://www.rp-photonics.com/spotlight.html en-us RP Photonics Consulting GmbH, 2012 Fr, 03 Feb 2012 16:00:24 +0100 http://www.rp-photonics.com/spotlight_2012_02_03.html When doing simulations or modeling, a basic question is whether to use commercial software or home-made solutions. Fri, 3 Feb 2012 13:40:00 +0100 http://www.rp-photonics.com/spotlight_2012_02_03.html http://www.rp-photonics.com/spotlight_2011_12_23.html After many reports of thin-disk lasers mode-locked with SESAMs, there is now a Kerr lens mode-locked laser, which produces particularly short pulses, demonstrated by O. Pronin et al. at the Max-Planck Institute for Quantum Optics in Garching, Germany. Fri, 23 Dec 2011 15:08:00 +0100 http://www.rp-photonics.com/spotlight_2011_12_23.html http://www.rp-photonics.com/spotlight_2011_06_10.html This article debunks the widespread myth that a more compact optical resonator setup will always be more stable. In fact, the opposite can be the case: the alignment sensitivity can become very high. Fri, 10 Jun 2011 18:06:00 +0100 http://www.rp-photonics.com/spotlight_2011_06_10.html http://www.rp-photonics.com/spotlight_2011_05_28.html Two recent scientific papers discuss the suspected physical origin of a very nasty mode instability, as has been observed in some very high-power fiber amplifiers. The latest paper by A. V. Smith can be considered as reporting breakthrough results, very much clarifying the situation. Sat, 28 May 2011 14:16:00 +0100 http://www.rp-photonics.com/spotlight_2011_05_28.html http://www.rp-photonics.com/spotlight_2011_03_13.html The article follows an interesting gedanken experiment: How would our laser technology be affected if all the laser and pump transitions would be 100 times stronger, leading to very short upper-state lifetimes? Sun, 13 Mar 2011 11:29:00 +0100 http://www.rp-photonics.com/spotlight_2011_03_13.html http://www.rp-photonics.com/spotlight_2011_02_10.html The article discusses a number of issues which make the design and development of fiber lasers substantially more complicated and expensive than that of bulk lasers. The reasons for this are manyfold; they include the typically very high optical intensities (which cause strong saturation effects), the typical quasi-three-level peculiarities, ASE, pulse shaping mechanisms, and polarization issues. Thu, 10 Feb 2011 17:43:00 +0100 http://www.rp-photonics.com/spotlight_2011_02_10.html http://www.rp-photonics.com/spotlight_2011_01_05.html A recent paper reports an enormous peak power of 3.8 GW from a chirped-pulse fiber amplifier system. Although it might seem that the limits are pushed away every year, the article shows that there will not be much room for further increases of pulse energy and peak power. Wed, 5 Jan 2011 19:46:00 +0100 http://www.rp-photonics.com/spotlight_2011_01_05.html http://www.rp-photonics.com/spotlight_2010_09_02.html The article first explains a number of technical aspects, all showing that LEDs can be more energy efficient than any other light sources. Nevertheless, it then shows that rebound effects may well turn this into effectively more consumption, rather than less. The reason is basically that people generally use (and waste) more of what is available cheaply. Thu, 2 Sep 2010 20:34:00 +0100 http://www.rp-photonics.com/spotlight_2010_09_02.html http://www.rp-photonics.com/spotlight_2010_07_27.html When mode-locked high-power lasers were developed, a serious concerning was damage to the SESAMs used for mode locking. It turned out, however, that this issue was much smaller than expected, while other problems came up in the area of dispersion compensation. The concept of power scaling shows more clearly why this had to go that way. Tue, 27 Jul 2010 18:20:00 +0100 http://www.rp-photonics.com/spotlight_2010_07_27.html http://www.rp-photonics.com/spotlight_2010_07_12.html It is explained why it is so essential for cost-effective development and production to engage a highly qualified laser expert very early on. Mistakes made in the early stage can be very expensive. Mon, 12 Jul 2010 09:49:00 +0100 http://www.rp-photonics.com/spotlight_2010_07_12.html http://www.rp-photonics.com/spotlight_2010_06_09.html It is explained that a simple combination of a polarizer and a quarter waveplate can sometimes be used instead of a Faraday isolator. However, this approach has its limitations. Wed, 9 Jun 2010 20:54:00 +0100 http://www.rp-photonics.com/spotlight_2010_06_09.html http://www.rp-photonics.com/spotlight_2010_05_14.html The Encyclopedia of Laser Physics and Technology has become the victim of plagiarism, but RP Photonics fights against that - successfully so far. Fri, 14 May 2010 10:47:00 +0100 http://www.rp-photonics.com/spotlight_2010_05_14.html http://www.rp-photonics.com/spotlight_2010_04_26.html The article explains the difference between resolution and accuracy of a measurement, and describes an example case where the accuracy can be much higher than the resolution of a detector chip. Mon, 26 Apr 2010 14:47:00 +0100 http://www.rp-photonics.com/spotlight_2010_04_26.html http://www.rp-photonics.com/spotlight_2010_04_16.html It is discussed why laser diodes, in contrast to active fibers, cannot be made with very small refractive index contrast in order to obtain single-mode guidance in combination with very large mode areas. The key problem arises from the refractive index variations caused by the spatially varying carrier density. Fri, 16 Apr 2010 11:23:00 +0100 http://www.rp-photonics.com/spotlight_2010_04_16.html http://www.rp-photonics.com/spotlight_2010_04_08.html Curious behavior is observed when a nearly rectangular beam shape is generated. This, however, can be well understood considering Fourier optics. Thu, 8 Apr 2010 11:43:00 +0100 http://www.rp-photonics.com/spotlight_2010_04_08.html http://www.rp-photonics.com/spotlight_2010_03_22.html All-in-one concepts, where several functions are integrated into a single component, often look attractive at a first glance. The article shows, however, that moderate advantages often come at a high price. A modular approach is often much more powerful and practical. Mon, 22 Mar 2010 11:22:00 +0100 http://www.rp-photonics.com/spotlight_2010_03_22.html http://www.rp-photonics.com/spotlight_2010_03_15.html It is well known that the phenomenon of spatial walk-off can degrade the beam quality in nonlinear conversion processes. The article shows, however, that this is not necessarily the case, even in cases with strong walk-off. Mon, 15 Mar 2010 10:17:00 +0100 http://www.rp-photonics.com/spotlight_2010_03_15.html http://www.rp-photonics.com/spotlight_2010_03_09.html It is discussed why in the context of modeling of fiber amplifiers and lasers it is normally reasonable to treat nonlinear effects only to a limited extent. Tue, 9 Mar 2010 08:50:00 +0100 http://www.rp-photonics.com/spotlight_2010_03_09.html http://www.rp-photonics.com/spotlight_2010_03_03.html The article explains why 'threshold' values are often given for the onset of nonlinear effects, how Raman and Brillouin scattering lead to nonlinear power losses, and how nonlinear effects can be reduced in fiber amplifiers. Wed, 3 Mar 2010 12:33:00 +0100 http://www.rp-photonics.com/spotlight_2010_03_03.html http://www.rp-photonics.com/spotlight_2010_02_26.html A new paper of Dr. Paschotta appeared in Optics Express. It presents news results on the timing jitter and phase noise of mode-locked fiber lasers. Fri, 26 Feb 2010 09:39:00 +0100 http://www.rp-photonics.com/spotlight_2010_02_26.html