| Bow-Tie PM Fiber | Two stress-applying parts are positioned on opposite sides of the fiber core. The induced stress creates strong birefringence between the two principal axes. | Commonly available for approximately 780 nm, 850 nm, 980 nm, 1060 nm, 1310 nm, and 1550 nm designs. | Typically about 1–3 mm, depending on wavelength and fiber design. | Commonly about 0.3–3 dB/km near the intended operating wavelength. | High polarization extinction capability; mature design; good axis definition; suitable for many standard PM passive components. | Stress structure can increase sensitivity to bending, coating conditions, temperature, and connector alignment. | A strong general-purpose choice for fiber interferometers, gyroscopes, polarization-sensitive sensors, coherent links, PM patch assemblies, and laboratory optical systems. |
| Panda PM Fiber | Two circular stress-applying rods are placed symmetrically beside the core. The geometry produces birefringence while retaining a relatively simple circular fiber profile. | Commonly designed for 780 nm, 850 nm, 980 nm, 1060 nm, 1310 nm, and 1550 nm. | Typically about 1–5 mm, with the exact value determined by the stress-rod geometry and glass composition. | Commonly about 0.2–2 dB/km in the specified operating band. | Good mechanical handling; relatively consistent geometry; widely used for polarization control and component pigtails. | Polarization performance can vary with bend radius, temperature, splicing, and the quality of axis alignment during assembly. | Well suited to integrated optical modules, interferometric sensors, PM couplers, fiber lasers, coherent receivers, and compact systems requiring practical splicing and handling. |
| Elliptical-Core PM Fiber | The fiber core has an intentionally elliptical shape. Form birefringence separates the two orthogonal polarization modes without relying primarily on external stress rods. | Often optimized for visible, near-infrared, or specialized wavelength bands, including approximately visible 630–780 nm and near-infrared 850–1550 nm. | Frequently around 1–10 mm, depending on the ellipticity and core design. | Commonly about 0.5–5 dB/km, with specialty versions potentially higher. | Simple birefringent concept; can provide strong polarization separation; useful where a non-circular mode profile is acceptable. | Elliptical mode shape can complicate coupling, connectorization, splicing, and compatibility with standard circular-core components. | Best for specialty sensors and custom optical assemblies where polarization discrimination is important and the system can accommodate a non-circular mode field. |
| Side-Hole or Side-Tunnel PM Fiber | Air holes or low-index regions are formed beside the core. The asymmetric geometry creates high birefringence and can also enable interaction with the surrounding environment. | Commonly produced for visible and near-infrared operation, with designs frequently covering approximately 633–1550 nm. | Often below 2 mm in high-birefringence designs, but the value is highly dependent on hole geometry and wavelength. | Frequently about 1–10 dB/km; specialty structures may have higher loss. | Very strong birefringence potential; useful for compact polarization devices, sensing, and designs requiring access to the optical field. | More difficult fabrication and cleaving; higher loss and greater packaging sensitivity are common compared with conventional solid-glass PM fibers. | Suitable for advanced sensing and research systems, including pressure, strain, temperature, chemical, microfluidic, and polarization-selective specialty devices. |
| Photonic Crystal PM Fiber | A periodic air-hole cladding and an intentionally asymmetric core or hole arrangement create birefringence and guide light by modified total internal reflection or related mechanisms. | Available in specialty designs from the visible range through the near-infrared; operating wavelength is strongly design-specific. | Often approximately 0.5–5 mm, although specialized structures may fall outside this range. | Commonly about 1–20 dB/km, with performance varying greatly by design, wavelength, and fabrication quality. | Flexible control of mode area, dispersion, birefringence, nonlinear response, and wavelength range; supports highly customized optical behavior. | Higher cost and integration complexity; coupling, cleaving, splicing, connectorization, and environmental packaging require careful engineering. | Best for research, nonlinear optics, ultrafast lasers, specialty spectroscopy, and custom high-performance systems where standard PM fiber cannot meet the design targets. |
| Polarization-Maintaining Single-Mode Fiber | A single-transverse-mode fiber with deliberately high birefringence, commonly implemented using bow-tie, panda, elliptical-core, or related structures. | Selected for the system band, commonly 780–1060 nm, 1310 nm, or 1550 nm. | Usually about 1–5 mm for conventional high-birefringence designs. | Often approximately 0.2–3 dB/km in the intended operating band. | Predictable fundamental-mode behavior; straightforward integration with PM lasers, modulators, detectors, and passive components. | Does not automatically preserve polarization after poor splicing, excessive bending, connector misalignment, or operation outside the specified band. | The default choice for most polarization-sensitive single-mode architectures, including coherent communications, fiber sensors, interferometers, and precision measurement systems. |
| Polarization-Maintaining Large-Mode-Area Fiber | A PM structure is combined with a larger effective mode area to reduce optical intensity and nonlinear effects while maintaining polarization discrimination. | Commonly designed for approximately 1.0–1.1 µm and 1.5–1.6 µm systems, with other specialty wavelengths available. | Typically about 1–10 mm, depending on the required polarization stability and mode-field diameter. | Commonly about 0.5–5 dB/km; high-power specialty designs may trade loss against mode area and handling performance. | Higher power-handling capability; reduced nonlinear phase accumulation; useful for narrow-linewidth and high-energy polarized sources. | More sensitive to bending and higher-order mode excitation; alignment and launch conditions are more demanding than for standard PM single-mode fiber. | Recommended for high-power fiber lasers, amplifiers, coherent beam delivery, and low-nonlinearity systems requiring linearly polarized output. |
| Polarization-Maintaining Multimode Fiber | A birefringent fiber supports more than one spatial mode while maintaining preferential polarization axes. Polarization stability is therefore coupled to modal control. | Typically selected for visible, 850 nm, 980 nm, 1060 nm, or 1550 nm systems, depending on core size and application. | Often about 1–10 mm, with the effective value depending on the guided modes. | Commonly about 1–10 dB/km, depending on core diameter, numerical aperture, wavelength, and mode-management requirements. | Supports higher optical power or relaxed coupling requirements than single-mode PM fiber; can provide larger mode area. | Modal dispersion and differential modal behavior can reduce polarization stability and system bandwidth; mode control is essential. | Use selectively for high-power delivery, specialty illumination, imaging, and systems where modal behavior is characterized and acceptable. |
| PM Fiber for Fiber-Optic Gyroscopes | Usually a low-loss, low-birefringence-drift PM design optimized for long sensing coils, stable polarization axes, and low polarization cross-coupling. | Frequently optimized around 1310 nm or 1550 nm, depending on the gyroscope architecture and optical source. | Commonly selected in the approximate range of 1–4 mm for coil applications. | Often targeted below approximately 1 dB/km in high-performance designs, although the required value depends on coil length and architecture. | Low polarization cross-coupling; suitable for long coils; can support stable interferometric measurements when winding and thermal behavior are controlled. | Coil winding stress, temperature gradients, radiation, connector losses, and splice quality can significantly affect bias stability and scale-factor performance. | Best suited to navigation-grade and precision interferometric fiber gyroscopes when accompanied by qualified coil winding and environmental testing. |
