Optical Circulator | 3-Port & 4-Port for Bidirectional Transmission

Introduction

Opelink is a leading manufacturer of Optical Circulators, providing high-performance solutions for bidirectional optical transmission systems. With 13+ years of expertise in optical passive components, we serve telecom operators, equipment manufacturers, and research institutions worldwide.

An optical circulator is a non-reciprocal passive device that routes light signals in a specific sequence from port to port. In a 3-port circulator, light entering port 1 exits port 2; light entering port 2 exits port 3; and light entering port 3 is isolated. This unique property enables bidirectional transmission over a single fiber, significantly reducing fiber infrastructure costs.

Opelink offers 3-port and 4-port circulators in polarization insensitive and polarization maintaining versions. Our products feature high isolation (>40dB), low insertion loss (<0.6dB), and excellent environmental stability. All circulators are Telcordia GR-1221 qualified and manufactured in our ISO 9001:2015 certified facility.

Product Types

1. 3-Port Circulator
The standard configuration for most applications. Routes signals from port 1→2, 2→3, with isolation from port 3→1. Used in DWDM systems, OADM, and fiber sensors.

2. 4-Port Circulator
Extended configuration with an additional port. Routes signals 1→2, 2→3, 3→4. Used in advanced optical systems requiring additional signal paths.

3. Polarization Maintaining (PM) Circulator
Preserves the polarization state of light through the circulator. Essential for coherent systems, interferometric sensors, and polarization-sensitive applications.

4. High Power Circulator
Designed for fiber laser and amplifier applications with enhanced thermal management. Available for power levels up to 10W, 20W, or custom requirements.

Technical Specifications

Parameter	3-Port	4-Port	PM Type
Center Wavelength	1310/1550nm	1310/1550nm	1550nm
Insertion Loss	≤0.6dB	≤0.8dB	≤1.0dB
Isolation	≥40dB	≥40dB	≥35dB
Crosstalk	≥50dB	≥50dB	≥50dB
Return Loss	≥50dB	≥50dB	≥50dB
PDL	≤0.15dB	≤0.20dB	≤0.10dB
Operating Temp	-40°C to +85°C	-40°C to +85°C	-40°C to +85°C
Max Power	500mW	500mW	300mW

Applications

• DWDM Systems: Bidirectional transmission and add-drop multiplexing
• OADM (Optical Add-Drop Multiplexer): Channel add/drop in ring networks
• Fiber Sensors: Interferometric and Bragg grating sensor systems
• EDFA Amplifiers: Signal routing in optical amplifiers
• Dispersion Compensation: Combining DCM with transmission fiber
• OTDR Testing: Fiber testing and monitoring applications

FAQ

Q1: How does an optical circulator work?

A: An optical circulator uses non-reciprocal optical elements (typically Faraday rotators) to route light in a specific direction. Light entering port 1 exits port 2; light entering port 2 exits port 3 (and port 4 in 4-port models). This enables bidirectional transmission over a single fiber, reducing fiber count and infrastructure costs.

Q2: What is the difference between 3-port and 4-port circulators?

A: 3-port circulators route signals 1→2→3 and are used in most standard applications. 4-port circulators add an additional port (1→2→3→4) for more complex routing requirements. Choose based on your system architecture and signal path requirements.

Q3: Can circulators be used with high-power lasers?

A: Standard circulators handle up to 500mW. For fiber laser applications, Opelink offers high-power circulators rated for 10W, 20W, or higher with enhanced thermal management. Always specify your power requirements when ordering.

Q4: What is the difference between polarization insensitive and PM circulators?

A: Polarization insensitive circulators work with any input polarization state. PM circulators preserve the polarization state and are used in coherent systems, sensors, and applications requiring polarization control. PM circulators require alignment to the slow axis of PM fiber.

Q5: Do you offer custom specifications?

A: Yes, Opelink provides custom center wavelengths, bandwidths, port configurations, and power handling capabilities. We can design circulators for specific applications including wideband operation, multi-wavelength, or extreme temperature ranges. Contact our sales team for custom requirements.