Concerning the November 2009 edition of Laser Focus World, we have read the article on tunable sources—"Fully tunable visible laser source is valuable for biophotonics," by Frank Lison and Thomas Hellerer.1
We would like to inform you and your readers that a new product on the market dispels a presumption regarding tunable sources based on supercontinuum sources.
More precisely, the presumption is concerning "the suppression of neighboring unwanted colors is currently only possible to the order of 10-4..." Photon etc.'s tunable laser source has a measured out-of-band rejection on the order of 10-6 and would be potentially better if our measurement system were not limited by the noise floor of our optical spectrum analyzer (see figure).
These numbers show that sources can successfully be used for photoluminescence excitation continuously tunable between 400 nm and 1000 nm.
REFERENCES
1.F. Lison and T. Hellerer, "Fully tunable visible laser source is valuable for biophotonics," Laser Focus World, 53 (November 2009).
Marc Verhaegen
Vice President R&D, Photon etc., Montreal, QC, Canada, www.photonetc.com