Polarization Maintaining Fiber Optical Isolator 1310nm 1480nm 1550nm Low Insertion Loss

The PM Isolator is a high-performance passive device based on a panda-shaped polarization-maintaining fiber design. It primarily operates in mainstream communication wavelengths such as 1310 nm, 1480 nm, and 1550 nm, enabling unidirectional transmission of optical signals and effectively suppressing back reflections and feedback. The product offers two structures: Single Stage and Dual Stage, as well as P-grade and A-grade accuracy levels, allowing users to flexibly balance insertion loss and isolation. The device uses cornering PM panda polarization-maintaining fiber, with the slow axis aligned with the connector key, and the fast axis can be selectively blocked or operated simultaneously, structurally ensuring the consistency and controllability of the polarization state in the transmission link. Compact packaging options include a φ5.5*L35 mm steel tube (suitable for bare fiber or 0.9 mm loose tube) and a 90*20*10 mm ABS box package (suitable for 2/3 mm fiber optic cable), facilitating integration into modules, chassis, or experimental platforms.

At the system application level, the PM Isolator is primarily used in various polarization-dependent fiber optic systems that are extremely sensitive to reflection and feedback. In EDFA fiber amplifiers, polarization-maintaining isolators are typically placed at the input, output, or interstage locations to suppress backlight from fiber optic links and subsequent devices, preventing gain oscillations and noise amplification. In fiber lasers, polarization-maintaining isolators act as "one-way valves" at the external output, blocking reflections from downstream optical paths, protecting the resonant cavity and active devices, and improving the stability and unidirectionality of laser output. In fiber optic sensing, optical communication measurement, and precision optical instruments, they shield the measured end or end face from reflections, avoiding the influence of multipath interference and parasitic feedback on measurement results, thereby improving system linearity, repeatability, and long-term reliability.

In terms of performance indicators, this series of polarization-maintaining isolators combines advantages such as low insertion loss, high isolation, high extinction ratio, and high return loss. The operating wavelengths are 1310/1480/1550 nm, with a bandwidth of ±20 nm. At 23°C, the typical insertion loss is approximately 0.4 dB for a single-stage P-class device, 0.5 dB for an A-class device, and only 0.5–0.6 dB for a two-stage structure. The maximum insertion loss remains within the 0.55–0.80 dB range over an operating temperature range of -5 to +70°C. In terms of peak isolation, the single-stage device achieves 42/40 dB, and the two-stage device achieves 58/55 dB. Isolation within the operating bandwidth is maintained at ≥28/26 dB (single-stage) and ≥48/45 dB (two-stage), respectively, effectively suppressing reverse light leakage. Depending on the axial operating mode, Type 1 (Fast axis blocked) achieves an extinction ratio of ≥20/18 dB when the fast axis is blocked, while Type 2 (Both axis working) achieves an extinction ratio of no less than 25/23 dB when both axes are working simultaneously, providing ample margin for different polarization schemes. All versions exhibit a return loss of ≥55 dB, a maximum optical power handling capacity of ≤300 mW, an operating temperature of -5～+70 ℃, and a storage temperature of -40～+85 ℃, demonstrating excellent environmental adaptability and long-term stability.

From a system integration perspective, the PM Isolator can be used as a standalone device connected in series in the optical path, or embedded in amplification modules, laser modules, sensor demodulators, or test platforms to form a fixed functional unit. For example, within an EDFA or Raman amplifier module, a single-stage isolator can be added at the input to prevent link reflections from affecting the preceding amplification stage; a double-stage isolator at the output can maintain low insertion loss while achieving high isolation, suitable for systems with high OSNR requirements. In a seed source + power amplifier stage combination structure, a PM Isolator can be inserted between stages to clearly separate energy and signal flows, facilitating power monitoring and fault location; in fiber optic sensor demodulators and interferometric measurement systems, isolators can be added at the light source or before critical interfaces to protect against external reflections and impacts from mis-insertion. By selecting different packages (φ5.5*35 mm steel tube / 90*20*10 mm ABS box), fiber optic sheaths (250 μm, 0.9 mm, 2.0 mm, 3.0 mm), and connector combinations, engineers can easily integrate it into 1U/2U chassis, module trays, or desktop experimental platforms.

Compared to ordinary single-mode optical isolators, the core advantage of the PM Isolator lies in its polarization maintenance capability and design flexibility. Utilizing Corning PM Panda polarization-maintaining fiber and aligning the PM fiber and connector keying with the slow axis ensures a clear reference for the polarization direction during splicing, cabling, and use, significantly reducing power fluctuations, phase noise, and measurement instability caused by random polarization drift. Furthermore, the product offers various combinations such as single-stage/dual-stage, P-stage/A-stage, and Type 1/Type 2 (fast axis blocking/dual-axis operation), allowing users to find the optimal balance between insertion loss, isolation, extinction ratio, and cost for their project needs. The specifications clearly state that with connectors, insertion loss increases by approximately 0.3 dB, return loss decreases by approximately 5 dB, and extinction ratio decreases by approximately 2 dB, facilitating accurate modeling in link budgets and system simulations. With detailed order codes (including wavelength, order, axis, package type, fiber type, length, and connector fields), the PM Isolator enables rapid selection and reuse across different projects, reducing the complexity of design, inventory, and maintenance.

In summary, the PM Isolator is a critical polarization-maintaining passive device for EDFA, fiber lasers, fiber optic sensors, and precision optical instruments. Through a combination of low insertion loss + high isolation + high extinction ratio + high return loss + polarization-maintaining Panda fiber, it provides stable and reliable unidirectional optical path protection and polarization control for polarization-sensitive systems. It significantly suppresses reflection and feedback, improves system OSNR and long-term stability, and simplifies optical path design and integration while ensuring polarization consistency. For equipment manufacturers and system integrators seeking high-performance, high-reliability, and mass-producible solutions, the appropriate selection and configuration of the PM Isolator will lay a solid foundation for the optical performance of the entire system and network, and reserve ample space for future functional expansion and network evolution.