An optical circulator is simply a three-port device that allows bidirectional transmission over a single fiber by allowing incoming light from port 1 to exit from port 2 and transmitting the reflected light from port 2 to port 3 instead of port 1.
It functions just like an isolator, protecting the input fiber from returning light but unlike an isolator, it allows the rejected light to be employed for later use.
Optical circulators can be categorized into two groups:
- Polarization-maintaining (PM) optical circulators
- Polarization-insensitive optical circulators
In this guide, we are going to focus on polarization-insensitive optical circulators and discuss the basics you should know about.
What is a polarization-insensitive optical circulator?
Also known as a polarization-independent optical circulator, a polarization-insensitive (PI) optical circulator is a non-reciprocal optical passive component that allows bi-directional transmission of arbitrarily polarized light over a single fiber.
When to use polarization-insensitive optical circulators?
Unlike its PM circulators that are used for applications that need light to maintain its polarization state, polarization-insensitive optical circulators are best suited for applications where you need to process randomly polarized light because of the rapid changes in the polarization state of the light traveling in a fiber.
Like other optical circulators, polarization-insensitive optical circulators can further be sub-categorized into two categories:
- Low-power PI circulators
- High-power PI circulators
As their names suggest, low-power PI circulators are capable of handling only low power, and high-power PI circulators can be used for applications that employ high power. So, when buying PI optical circulators, one should keep in mind the application and power requirements.
What makes a good polarization-insensitive optical circulator?
A good polarization-insensitive optical circulator is characterized by the following features:
- Low insertion loss
- Excellent isolation
- Low polarization-dependent loss (PDL)
- Exceptional environmental stability
- Affordable price
- High-quality construction
- Optimal reliability
What are the uses and applications of polarization-insensitive optical circulators?
Polarization-insensitive optical circulators are widely used with fiber gratings and available in a wide range of specifications which make them suitable for a variety of applications. Some of the most popular applications of polarization-insensitive optical circulators are:
- WDM systems
- Fiber amplifiers
- Pump laser source
- Instrumentation
- Fiber optic sensor
- Test & measurement
- Wavelength Add/Drop
- Bi-direction communication systems
- Dispersion compensation
DK Photonics is the leading China-based manufacturer of an extensive range of optical circulators, including PM circulators and polarization-insensitive optical circulators. For any purchase query related to optical circulators, please feel free to get in touch.
