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Fibercore PS Series Photo-Sensitive Fibers for Advanced Telecommunications
Fiber Photosensitivity: Boron/Germania Doping
Photosensitivity in optical fiber enables UV-inscribed refractive-index gratings (FBGs). Fibercore’s PS series amplifies this effect by co-doping the core with boron and germania. This Ge–B co-doping “gives extremely high photosensitivity”, allowing high-reflectivity gratings to be inscribed very rapidly without hydrogen loading. In fact, PS fibers offer a “strong and consistent degree of photosensitivity indefinitely” straight from the shelf. Such high sensitivity supports very strong FBGs, key enablers of dense-WDM systems. High Ge/B doping thus eliminates slow H₂ loading processes, simplifies FBG fabrication, and produces deep notches that are essential for DWDM filtering and sensing.
High-Reflectivity Gratings and Splice Compatibility
Mode-field diameters (MFDs) are matched to standard single-mode fiber, so UV-written gratings splice with minimal loss. Fibercore notes that the “mode field diameters … are engineered so gratings may be spliced into standard telecommunications [fibers] with minimal excess loss”.
In practice, a PS1250/1500 fiber has an MFD around 8.8–10.6 μm (at 1550 nm), closely matching SMF-28. This yields low-loss splices when inserting PS-based FBGs into DWDM modules or pigtails. At the same time, the boron–germanium core enables very strong FBG reflectivity in a single UV writing step, allowing narrowband filters or sensor channels to be fabricated simply. These high-reflectivity gratings are ideal for precise filtering in WDM multiplexers, gain-flattening filters, pump laser stabilization, and other telecom devices.
Specifications and Performance
PS fibers cover key telecom bands with low attenuation. For example, PS1250/1500 (1260–1650 nm) has ~9 μm MFD and only ~0.10–0.12 dB/km loss. PS980 (≈980 nm) has ~6 μm MFD and ~0.20 dB/km loss. Even PS750 (≈780 nm) achieves ~0.30 dB/km with ~5 μm MFD. In each case, PS fiber attenuation is comparable to standard SMF-28.
- PS1250/1500 (dual-band): MFD ~8.8–10.6 μm; attenuation ~0.10 dB/km at 1310 nm and ~0.12 dB/km at 1550 nm.
- PS980: MFD ~5.6–6.8 μm; attenuation ~0.20 dB/km (@980 nm).
- PS750: MFD ~4.4–5.9 μm; attenuation ~0.30 dB/km (@780 nm).
All PS fibers use standard 125 μm cladding (dual acrylate coating) and splice just like telecom fiber. Notably, PS1250/1500 was explicitly designed to match 1310/1550 nm telecom fiber, making it ideal for DWDM add/drop modules and EDFA gain-flattening filters. These engineered MFDs ensure that PS fibers can integrate seamlessly into metro/access rings and long-haul links with very low splice loss.
Underwater and Infrastructure Sensing Applications
PS fibers also excel in sensing and harsh-environment roles. High-strength fibers with embedded FBGs are widely used as underwater hydrophones and seismic sensors. Fibercore’s high-strength SM fibers (e.g. 50 μm cladding) have been used in submarine hydrophone arrays With their high photosensitivity and options for rugged coatings (e.g. polyimide), PS fibers can be embedded in pipelines, bridges or telecom towers to monitor strain or temperature. For example, distributed acoustic sensing (DAS) uses telecom fiber to monitor pipelines or railways for leaks or intrusion. Writing PS fiber FBG arrays along the fiber allows a single cable to carry both data traffic and sensing signals, providing continuous infrastructure monitoring without separate sensor wiring.
Manufacturing and Cost Advantages
Because PS fibers are photosensitive out of the box, FBG fabrication is much simpler and cheaper. No hydrogen-loading means UV inscription alone creates the desired index change. Fibercore notes that PS fibers allow “rapid inscription of high reflectivity FBGs” without H₂. In practice, deep gratings can be written in seconds (for example, with a 248 nm excimer laser) instead of the minutes or hours required for hydrogenated fiber. This dramatically reduces production time and cost per grating. High-throughput FBG inscription in PS fibers lowers capital and labor costs for WDM filter and sensor module manufacturers, facilitating broader deployment of fiber-based sensors and devices.
Industry Use Cases
- Pipeline Monitoring: Distributed FBG/DAS sensors detect leaks or strain along pipelines. PS fiber’s high reflectivity simplifies creating long sensor spans in oil & gas lines.
- Metro/Access Networks: City DWDM rings use compact FBG filters for add/drop. PS fibers enable high-reflectivity gratings to be spliced into metro network nodes with minimal loss.
- 5G Backhaul: Long links between 5G base stations require precise filtering and dispersion control. PS-based FBG filters and compensators maintain signal integrity on these fiber routes.
- Submarine Systems: Undersea EDFAs (C+L band repeaters) use FBGs for pump stabilization and gain flattening. PS fibers simplify writing these gratings in amplifier modules. Subsea hydrophone arrays (for cable health and security) likewise benefit from PS fiber’s durability.
## Enabling Next-Generation Optical Networks
Fibercore’s PS Series fibers are enabling advanced telecom networks. Their high photosensitivity underpins dense-WDM multiplexers and broadband amplifiers. PS1250/1500 supports writing gratings at both 1310 nm and 1550 nm, ideal for C+L-band EDFAs and wideband filter banks. These fibers also enable distributed sensing over long distances. By combining specialty performance with telecom-grade loss and spliceability, PS fibers allow higher channel counts, broader bands, and more reliable fiber networks.
Sources: Technical data and application notes from Fibercore and industry references
Also Read: Low-Noise, High-Gain Optical Amplification: The Technical Backbone of Fibercore EDFA Fibers