Higher-order modes limit pulse broadening in ultrafast fiber lasers

June 1, 2009
The ytterbium (Yb) and erbium (Er) fibers used in ultrafast fiber lasers are, like any other optical fibers, subject to chromatic dispersion, which results in pulse broadening.

The ytterbium (Yb) and erbium (Er) fibers used in ultrafast fiber lasers are, like any other optical fibers, subject to chromatic dispersion, which results in pulse broadening. To reduce or eliminate dispersion in ultrafast fiber lasers, OFS (Norcross, GA) developed an all-fiber module called FemtoComp in its Brøndby, Denmark facility.

Dispersion is defined as “anomalous” when short wavelengths travel faster than long ones. Erbium fibers in the 1550 nm range are easily compensated because of the availability of conventional fibers with both normal and anomalous dispersion at this wavelength; however, the fundamental modes of conventional and ytterbium fibers have normal dispersion between 1000 and 1100 nm. Bulk-optic components often used to compensate dispersion reduce stability and increase loss in the fiber cavity. Conventional fibers can be designed, however, so that higher-order modes (HOMs) exhibit anomalous dispersion. The all-fiber module consists of a mode converter (long-period grating) on the input (converting the mode into an HOM), a length of HOM fiber where the mode experiences anomalous dispersion, and a mode converter on the output. Contact Poul Erik Schmidt at [email protected].

Sponsored Recommendations

March 31, 2025
Enhance your remote sensing capabilities with Chroma's precision-engineered optical filters, designed for applications such as environmental monitoring, geospatial mapping, and...
March 31, 2025
Designed for compatibility with a wide range of systems, Chroma's UV filters are engineered to feature high transmission, superior out-of-band blocking, steep edge transitions...
March 31, 2025
Discover strategies to balance component performance and system design, reducing development time and costs while maximizing efficiency.
March 31, 2025
Filter accessories including cubes, sliders, and rings, designed to enhance the performance and versatility of optical systems. These components ensure precise alignment and stability...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!