TruePhase® 125/250 µm 1550 nm PM Optical Fibre

Technology
Speciality fibre
Partner
Lightera (formerly OFS)

The TruePhase 125/250 µm 1550 nm polarisation-maintaining optical fibre is a high-performance single-mode fibre designed for applications that require a stable state of polarisation. It maintains the polarisation of light across its length, which is crucial for interferometers, fibre-optic gyroscopes, and other precision optical systems. With a standard 125 µm cladding and 250 µm coated diameter, this PM fibre integrates seamlessly with conventional fibre connectors and splicing tools. It exhibits low attenuation at the 1550 nm telecom window, ensuring minimal signal loss even over extended runs. Engineers choose this fibre for its high polarisation extinction ratio and consistency, which translates to reliable and accurate performance in polarisation-sensitive setups. Common uses include telecommunications, fibre-optic sensing, and scientific research, where maintaining light polarisation is essential for system stability and measurement accuracy.

TruePhase® 125/250 µm 1550 nm PM Optical Fibre
IntroFeaturesDownloadsSpecificationsContactFAQ

Range features

A high level overview of what this range offers

  • Polarisation-maintaining design: Keeps light polarised along a fixed axis for consistent performance in polarisation-sensitive systems.
  • Optimised for 1550 nm: Designed for low loss and stable operation in the C-band for telecom and precision sensing applications.
  • Standard 125 µm cladding: Supports compatibility with common connectors, patch cords, and fusion splicing equipment.
  • 250 µm protective coating: Adds durability and handling protection while maintaining routing flexibility.
  • Low optical attenuation: Typically offers attenuation of ≤ 0.5 dB/km at 1550 nm for efficient long-distance or coiled-fibre use.
  • High extinction ratio: Helps preserve the desired polarisation state for accurate sensing and interferometric measurements.
  • Proof-tested reliability: Strength-tested to support robust installation and dependable long-term use.
  • Single-mode operation: Eliminates multimode distortion for stable, coherent optical transmission.

Downloads

for TruePhase® 125/250 µm 1550 nm PM Optical Fibre

TruePhase® 125/250 µm 1550 nm PM Optical Fibre – Datasheet
Download

What’s in this range?

All the variants in the range and a comparison of what they offer

Specification

Value

Fibre type

Polarisation-maintaining single-mode fibre

Operating wavelength

1550 nm (C-band)

Cladding diameter

125 µm

Coating (outer) diameter

250 µm (acrylate coating)

Numerical aperture (NA)

~0.12

Mode field diameter (at 1550 nm)

~10 µm

Attenuation @ 1550 nm

≤ 0.5 dB/km (typical)

Polarisation extinction ratio

≥ 20 dB (typical, short length)

Beat length @ 1550 nm

~3 mm (approximate)

Proof test level

100 kpsi (standard tensile proof test)

Operating temperature range

–40 °C to +85 °C (typical for acrylate)

FAQs

for TruePhase® 125/250 µm 1550 nm PM Optical Fibre

A polarisation-maintaining (PM) fibre is a specialised single-mode optical fibre that preserves the polarisation state of light as it travels through the fibre. In a standard single-mode fibre, external stress or small irregularities can cause the polarisation to drift or rotate. A PM fibre uses built-in birefringent structures so light launched into one principal axis stays aligned to that axis. This makes PM fibre essential in interferometers, sensors, and other systems where polarisation stability directly affects performance.

1550 nm is widely used in fibre optics because it lies in a low-loss transmission window of silica fibre. This allows light to travel with very little attenuation, making it highly suitable for telecommunications, sensing, and precision photonics. The TruePhase PM fibre is optimised for this wavelength so its attenuation and birefringent performance are well matched to 1550 nm systems.

The 125 µm value refers to the diameter of the glass cladding, which is the standard size used across many optical fibre handling systems. The 250 µm value refers to the outer diameter after the protective coating is applied. This means the fibre combines standard mechanical compatibility with an added coating layer that protects against scratches, moisture, and handling damage.

PM fibres have defined fast and slow axes that must be aligned correctly to preserve the launched polarisation. During splicing, specialised PM fusion splicers are used to align the fibre axes before joining. During connectorisation, keyed PM connectors help maintain the correct axis orientation. Proper alignment minimises crosstalk and ensures the fibre maintains polarisation effectively.

Yes, this fibre is single-mode at 1550 nm. Single-mode operation means only the fundamental mode propagates through the fibre, eliminating multimode dispersion and preserving signal clarity. In PM applications, this is especially important because it ensures stable, coherent transmission while allowing the fibre to preserve the intended polarisation state.

Polarisation extinction ratio (PER) indicates how well the fibre keeps optical power aligned with the intended polarisation axis instead of leaking into the orthogonal axis. A high PER means the launched polarisation is preserved very effectively. This is valuable in interferometry, sensing, and research applications where even small polarisation errors can reduce accuracy or signal quality.

This fibre typically offers attenuation of ≤ 0.5 dB/km at 1550 nm, which is very low. In many laboratory, instrumentation, and sensing setups, this means fibre loss is negligible over practical lengths. Low attenuation gives designers more flexibility for routing, coiling, or extending fibre runs while maintaining strong signal levels and good signal-to-noise performance.

Yes, the fibre can generally be bent or coiled under normal handling conditions while maintaining its performance. However, excessively tight bends or kinks can introduce additional stress, loss, or some degradation in polarisation preservation. Following the recommended minimum bend radius from the datasheet is the best way to maintain reliable attenuation and PM performance.

This fibre is well suited to applications where a fixed polarisation state must be preserved. Typical uses include fibre-optic gyroscopes, interferometric sensors, telecommunications components using polarised light, and quantum optics or photonics research. It is a strong choice wherever system stability, measurement accuracy, and polarisation fidelity are critical.

Related product ranges

ClearLite® 1310 nm 0.21 NA PYROCOAT® Optical Fibre
Lightera (formerly OFS)
ClearLite® 1310 nm 0.21 NA PYROCOAT® Optical Fibre

ClearLite 1310 nm 0.21 NA Pyrocoat is a single-mode optical fibre for 1310 nm and 1550 nm operation, optimised for harsh environments and tight bends. It offers a high numerical aperture (0.21) for improved bend tolerance and uses a high-temperature Pyrocoat® polyimide coating for reliable performance under extreme conditions.

ClearLite® 1550 nm 0.17 NA Optical Fibre
Lightera (formerly OFS)
ClearLite® 1550 nm 0.17 NA Optical Fibre

ClearLite 1550 nm 0.17 NA is a single-mode optical fibre optimised for operation at the 1550 nm wavelength with a nominal numerical aperture of 0.17. Its longer cut-off design and dual-layer acrylate coating provide improved bend performance and robust reliability for demanding photonic applications.

FE50MKxR 650 nm DC-50 MBd 50 m OptoLock® POF Transceiver
Firecomms
FE50MKxR 650 nm DC-50 MBd 50 m OptoLock® POF Transceiver

The FE50MKxR series is a compact 650 nm plastic optical fibre transceiver module with an OptoLock® connectorless interface. It enables reliable data communication up to 50 MBd over ~50 metres of POF without the need for separate fibre connectors.

FR00AxAR 650 nm Analogue DC-125 MHz RedLink® POF Receiver
Firecomms
FR00AxAR 650 nm Analogue DC-125 MHz RedLink® POF Receiver

The FR00AxAR series is a 650 nm plastic fibre optic receiver module that converts light signals from POF (Plastic Optical Fibre) into an electrical current. It features a high-speed silicon photodiode supporting up to 125 MHz analogue bandwidth, enabling reliable data transmission (up to ~250 Mbps) in industrial environments.

GiHCS® Multi-mode 62.5 µm Graded Index Optical Fibre
Lightera (formerly OFS)
GiHCS® Multi-mode 62.5 µm Graded Index Optical Fibre

The F14404 GiHCS® 62.5 µm graded-index optical fibre is a rugged multimode fibre built for industrial use. It combines a hard polymer cladding for high mechanical strength with a graded-index core that delivers enhanced bandwidth for reliable data communications in harsh environments.

OEM / ODM Passive Optical Components
Foss Group
OEM / ODM Passive Optical Components

FOSS offer a variety of standard and custom passive optical bare components, also modular or terminated with connectors.

Patch Panel Modular HDX 1U (144 Fibres)
Lightera (formerly OFS)
Patch Panel Modular HDX 1U (144 Fibres)

A high-density 1U fibre optic patch panel compatible with modular HDX cassettes, supporting up to 144 fibre connections in a single rack unit. It offers a compact, plug-and-play solution for managing large volumes of fibre links in data centre and telecom environments.

TruePhase® 400 µm 1400-1490 nm PM Optical Fibre
Lightera (formerly OFS)
TruePhase® 400 µm 1400-1490 nm PM Optical Fibre

The TruePhase® 1400–1490 nm Polarisation-Maintaining Optical Fibre (400 µm coating) is a specialised single-mode fibre optimised for the 1400–1490 nm wavelength band. It maintains a linear polarisation state over long distances, making it well-suited for high-power Raman optical amplification and other photonic applications requiring stable polarisation.