The LINOS Faraday Isolators - Qioptiq Q-Shop

Two Stage Faraday IsolatorsTechnical OverviewFI-x-5TI and FI-x-5TVDiode lasers are extremely sensitive toreflected radiation. Standard Faradayisolators typically achieve between 30dBand 40 dB isolation, which in some casesis not sufficient to suppress undesirablefeedback.Our two stage Faraday isolators weredeveloped for the special requirementsof diode lasers and square the standardisolation of single stage Faradayisolators. At the heart of this developmentis the use of two coupled isolatorstages together with the best polarizersavailable on the market.This configuration combines the exitpolarizer of the first stage with the entrypolarizer of the second stage to formone central polarizer.Arranging the polarity of the twomagnets to be opposite to each otherresults in two benefits: The polarizationdirection of the transmitted light remainsunchanged in the transmission directionand the effect of both magnetic fields isenhanced. Therefore this configurationalso leads to a more compact isolatorand a reduction of the optical pathlength which in turn enhances theoptical quality of the Faraday isolator.All optical surfaces are antireflectioncoated and the surfaces normal to thebeam axis are tilted. The polarizers aremounted in a way that allows easycleaning of the external optical surfaces.This guarantees that the isolation is notreduced by residual reflections andscattering from the isolator.Based on this special design a guaranteed60 dB isolation at the designwavelength, respectively within theadjustment range of ±10 nm, makesLinos two stage Faraday isolators thebest on the market.DLI, OverviewThe isolators of the DLI-series weredeveloped for the special requirementsof diode lasers in the visible spectrumand combine the outstanding isolationof a two stage isolator with the flexibilityof a tunable isolator.The DLI isolators are easily integratedinto an existing setup and can beadjusted to match any wavelengthwithout changing the laser polarizationor displacing the laser beam. Theisolators can be coarsely tuned byaltering the effective magnetic field inthe two isolator stages. A precisewavelength adjustment is possible byrotating the central polarizer with amicrometer set screw. The blockedradiation is deflected out of the isolatorat 90° with respect to the beam axis. It isnot absorbed by the interior of theisolator, but is available at the sidesurfaces of the polarizer and the exitwindow.DLI Injection LockingThe DLI injection version revolves thisoperating mode and uses the exitwindow for in-coupling of the seed laserfor injection locking while decouplingefficiently the master and the slave laserfrom each other at the same time. Likethis stable mode locking (e.g. of Ti:Sapphire lasers) is simplified.ApplicationsAll two stage isolators are typically usedto improve the power and frequencystability of diode lasers used in spectroscopy,interferometry and precisioncontrol as well as in alignment applications.Since the output polarization andthe beam position are conserved for alltwo stage Faraday isolators, the influenceof the smallest feedback effects onthe laser can be quantitatively examined.1 Entrance polarizer2 Tuning micrometer3 Exit window4 waveband adjuster5 Exit polarizer6 Adjusting screw7 Mounting surface8 Protective ring642US-Phone +1 585 223-2370 UK-Phone +44 2380 744 500