Longitudinally-graded optical fibers

Abstract

Optical fibers have become ubiquitous tools for the creation, propagation, manipulation, and detection of light. However, while the intensity of light propagating through the fiber can increase or decrease along the length through amplification or attenuation, respectively, the properties of the fiber itself generally do not, thus removing an opportunity to further control the behavior of light and performance of fiber-based devices. Shown here are optical fibers that exhibit significant changes in their longitudinal optical properties, specifically a tailored longitudinal numerical aperture change of about 12% over less than 20 meters of length. This is about 1900 times greater than previously reported. The Brillouin gain coefficient was found to decrease by over 6 dB relative to a standard commercial single mode fiber. Next generation analogs are expected to exhibit more than a 10 dB reduction in SBS gain using larger, yet still reasonably manufacturable gradients over practical lengths.

Rational design of polyhedral oligomeric silsesquioxane fillers for simultaneous improvements of thermomechanical properties and lowering refractive indices of polymer films

“…Consequently, the reduction of the packing of the polymer chains likely occurs, resulting in the lowering refractivity. According to the recent reports, the degree of decreases in RIs by the present POSS fillers is large enough for the application of the optical fibers . Thus, our concept for the design of molecular fillers could be applicable in the practical materials.…”

Chirped Laser Seeding for SBS Suppression in a 100-W Pulsed Erbium Fiber Amplifier

“…On the other hand, broadening the Brillouin linewidth by combining different glasses in the core of a photonic crystal fiber [29] would lessen the impact of a chirped seed. However, broadening the linewidth by longitudinally grading the fiber [30] or varying the temperature [31] would reinforce the effect of a seed chirped in the appropriate direction.…”

Rethinking Optical Fiber: New Demands, Old Glasses

“…High-quality SMF may withstand controlled experiment up to 6 kg before breaking [134] Applied Distributed Heating (best case: assume pure silica core operating at 1064 nm or +1.6 MHz/K)~5 dB Low thermal stability of polymer coating serves as practical limit (<200-300°C) [135] Broaden Laser Spectrum (best-case: assume 75 MHz Brillouin spectral width near 1064 nm)~1 1 dB (for 1 GHz laser linewidth) Some system requirements do not support this method. For others, such as phased laser arrays, are limited to about 1 GHz or less spectral width [136] Longitudinally Graded Optical Fiber~6 dB shown; 10 dB possible Magnitude of compositional gradient along fiber [137] Radially Graded Optical Fiber~Few dB in LMA fibers and up to 10 dB in small-core fibers (<15 lm)…”

“…The choice of core precursor, often commodity crystals, processed directly into fiber above the precursor melting point yields fibers with core compositions that would be very difficult (if not impossible) to make using conventional production methods. The sapphire‐derived all‐glass optical fiber, as an example, exhibited the lowest Brillouin gain ever measured in stark contrast to the exotic methods and fiber designs used previously to reduce SBS; see Table for a comparison …”

“…The sapphirederived all-glass optical fiber, as an example, exhibited the lowest Brillouin gain ever measured in stark contrast to the exotic methods and fiber designs used previously to reduce SBS; see Table II for a comparison. 79,[134][135][136][137][138][139]…”