PM Fiber Output Lasers

Learn More About Polarization Maintaining Fiber

This light then exits the end of the fiber in a particular linear polarization state, and there is no (or very little) cross-coupling of optical power between the two modes of polarization. PM fibers’ principal operation relies on a systematic linear birefringence within the fiber. This defines two polarization modes along the length of the fiber with two unique phase velocities. This type of fiber is critical when attempting to deliver polarized light through a fiber optic cable for an application requiring the polarization to be preserved at the target.

In a typical, non-polarization-maintaining fiber, the circular symmetry allows both vertical and horizontal polarization modes to have the same phase velocity. Some birefringence is still present in these fibers, however. These bits of birefringence and even bends in the fiber can cause crosstalk between these two polarization modes. Even in a very short length of optical fiber, this crosstalk can lead to a power transfer from one polarization mode to another, effectively changing the polarization. This typically leads to a sort of random polarization, as the polarization will vary with changes in bends, other stresses, and wavelength.

Our Polarization-Maintaining Fiber Products

RPMC Lasers is your Polarization-Maintaining Fiber Laser supplier! We offer a wide range of PM fiber output lasers, including Laser Diode Modules, CW DPSS Lasers, CW Fiber Lasers, Multi-Wavelength Beam Combiners, Single-Emitter Laser Diodes, Distributed Feedback (DFB) Lasers, Volume Bragg Grating (VBG) Laser Diodes, and Superluminescent Laser Diodes (SLEDs or SLDs). Among these options, we provide many wavelengths from the UV to the SWIR spectral regions, many power options up to 10s of Watts, and narrow linewidth output options.

Deeper Dive into PM Fiber Output Lasers

Multimode vs Single-Mode Lasers for Raman Spectroscopy

The final and perhaps least obvious consideration is the samples crystallinity.  Crystallinity is a measure of how structured the atoms of molecules in a solid are ordered.  This is important because like all nonlinear effects, Raman scattering is polarization dependent, and if the sample is highly crystalline then the orientation of the sample relative to the laser’s polarization will affect the resultant Raman spectrum.  While always present, this effect is not noticeable in amorphous samples, because the random orientation of the atoms and molecules in the samples causes these variations to be averaged out.  Similarly, if the laser is randomly polarized then, the same averaging effect takes place, only by the laser’s random polarization as opposed to the samples random orientation.  For this reason, when analyzing crystalline materials, it is necessary to first ask the question, “Am I looking to analyze the crystalline structure, or identify the material?”  If the goal of your application is to study the crystalline structure, then single-mode lasers are generally preferable, due to the high polarization extension ratio.  On the contrary, if your goal is to repeatedly identify the material (for example is this crystal methamphetamine or rock candy), then a fiber-coupled multi-mode diode laser would be the best option due to its highly random polarization.

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HeNe Lasers vs Diode Lasers: HeNe Laser Pros and Cons

Despite of so many good intrinsic properties, HeNe lasers often do not meet the requirements of today’s industrial environments. Industrial production lines with 24/7 operation are all about robustness and long lifetime, thus industrial instrument manufacturers tend to pay 2 to 4 times more for a laser, which has a longer life-time, is easier to replace and maintain.

The price difference from HeNe lasers mainly depend on how many parameters of semiconductor lasers have to be close to the performance of HeNe. If one needs perfect beam quality, single-mode or polarization maintaining fiber has to be used to achieve <1.05 M2, nice round beam shape and diffraction limited divergence. Reasonably good central wavelength stability can by achieved by good temperature and power stabilization of the semiconductor emitter. Most difficult and expensive to achieve is the long coherence length requirement. Most popular way of ensuring high coherence length and very stable (<5 pm) central wavelength is to apply external cavity designs (ECDL – external cavity diode laser) by using volume Bragg gratings or fiber Bragg gratings.

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How Can We Help?

With over 25 years experience providing many types of laser diodes with various fiber-coupled output configurations to OEM integrators working in different markets and applications, and 1000s of units fielded, we have the experience to ensure you get the right product for the application. Working with RPMC ensures you are getting trusted advice from our knowledgeable and technical staff on a wide range of laser products.  RPMC and our manufacturers are willing and able to provide custom solutions for your unique application.

If you have any questions, or if you would like some assistance please Contact Us here. Furthermore, you can email us at info@rpmclasers.com to talk to a knowledgeable Product Manager.

Alternatively, use the filters on this page to assist in narrowing down the selection of PM Fiber lasers for sale. Finally, head to our Knowledge Center with our Lasers 101 page and Blogs, Whitepapers, and FAQ pages for further, in-depth reading.

Finally, check out our Limited Supply – In Stock – Buy Now page: This page contains an ever-changing assortment of various types of new lasers at marked-down/discount prices.