Optical Fiber Circulator

An optical circulator routes light in one direction only. Light entering port 1 leaves by port 2; light returning into port 2 leaves by port 3 and cannot travel back the way it came. That single property is what lets you put a laser behind an amplifier, a source behind a sensing line, or a transmitter and receiver on the same fiber without a splitter's 3 dB penalty.

HJ Optronics supplies 3-port and 4-port circulators from 640 nm to 2 µm, in polarization-maintaining (PM) and polarization-insensitive (PI) versions, with high-power variants where the application sends real wattage through the device.

Polarization maintaining or polarization insensitive?

A polarization-insensitive (PI) circulator takes light of any input state and works regardless of how the polarization drifts. It is the default choice for ordinary single-mode fiber: forward-pumped amplifiers, reflectometry, bidirectional links.

A polarization-maintaining (PM) circulator only preserves polarization if the light enters along the correct axis — the connector key must be aligned to the slow axis, and so must the fiber it is spliced to. Where that condition holds, it keeps the polarization state intact across the device, which is what coherent systems, PM fiber amplifiers, interferometric sensors and fiber lasers with polarization-sensitive components depend on. Getting the axis alignment wrong is the single most common reason a PM circulator appears to "lose" extinction ratio.

Three ports or four

A 3-port circulator gives one pass: 1 → 2, 2 → 3. A 4-port circulator continues that path — 1 → 2, 2 → 3, 3 → 4 — so a signal can make two passes through the same network, or upstream and downstream traffic can share one fiber without interference.

Power handling

Standard circulators (CIR, PICR, PMCIR, FCIR, FPMCIR) are built for signal-level power. The HPCIR and HPMCIR families are the high-power versions, for placement after a pump combiner or inside a power amplifier where hundreds of milliwatts to several watts pass through continuously.

Models

Model	Wavelength	Ports	Polarization	Notes
PCIR	640	3	PM	Both axes working
CIR	850	3	PI	—
PMCIR	850	3	PM	—
HPCIR	900 / 920 / 950	3	PM	High power
HPCIR	980	3	PI	High power
HPMCIR	980	3	PM	High power
MMCIR	980	3	PI	Multimode
CIR	1064	3	PI	—
PMCIR	1064	3	PM	—
HPCIR	1064	3	PI	High power
HPMCIR	1064	3	PM	High power
HPMCIRT	1064	3	PM	High power, tap monitor
PCIR	1550	3	PM	Both axes working
PMCIR	2000	3	PM	2 µm
CIR	2000	3	PI	2 µm
FPMCIR	2000	4	PM	2 µm, 4-port
PICIR	multi	3	PI	Standard single-mode
FCIR	multi	4	PI	—
PMCIR	multi	3	PM	—
FPMCIR	multi	4	PM	—

Priced per configuration — request a quote for current pricing and lead time. Full insertion loss, isolation, return loss and extinction ratio figures are on the datasheet linked from each product page — they are not repeated here because they vary by wavelength and connector option.

Choosing a wavelength

640, 850, 905–950 nm — visible and near-IR sources, sensing, OCT and spectroscopy build-ups.
976–980 nm — pump protection and pump combining ahead of an erbium or ytterbium stage.
1030–1080 nm — ytterbium fiber lasers, where the high-power PM parts usually sit.
1550 nm — telecom test, coherent systems, distributed sensing, Er-doped amplifiers.
2 µm — thulium and holmium work, mid-IR pumping, gas sensing.

Typical applications

Separating forward and backward light in fiber amplifiers and fiber lasers
Optical time-domain reflectometry and distributed acoustic or temperature sensing
Coherent transmission, where polarization state must survive the round trip
Protecting a source from back-reflections in high-power chains
Bidirectional transmission over a single fiber

Circulators are usually specified together with PM fiber components, isolators and fiber couplers — the three parts that make up most amplifier and sensing chains. If a configuration is not listed, we build to specification.

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3-port 1550 nm circulator JDS Uniphase CR5500P-3P-CV5A

CR5500P-3P-CV5A 3-port 1550 nm band circulator. Model #: CR5500P-3P-CV5A. If you need a different model number, please feel free to ask a quotatio...