An optical isolator is a key component in a fiber optic system. It allows the transmission of optical signals in the forward direction while blocking reflected energy back at the source to reduce the interference effect. In simple words, an optical isolator is an optical component that allows the light signal transmission in only one direction and prevents any unwanted feedback into the system.

PM Isolator

Optical isolators can be divided into two types depending on the polarization characteristics – polarization-dependent and polarization-independent. The polarization-dependent optical isolator is made of three components – a Faraday rotator, an input polarizer, and an output polarizer. It is used typically used in free-space optical systems. For example, a 1064nm high power in-line isolator is a polarization-dependent isolator that is used for a free-space optical system for signal transmission. The polarization independent isolator uses birefringent wedges at both input and output sources instead of a polarizer.

The function of an Optical Isolator

An optical isolator functions on the Faraday effect. A traditional optical isolator uses a faraday rotator as the main component sandwiched between two polarizers to generate the magneto-optic effect. The light signal traveling in the forward direction passes into the input polarizer to generate a polarized light signal in a vertical plane. Then it passes through the Faraday rotator to rotate the plane of polarization by 45° on-axis. The output polarizer is relatively aligned at 45° with the input polarizer to allow the polarized light to pass unimpeded. The output polarizer polarized the light traveling in the reverse direction by 45° and then it passes through the Faraday rotator to experience an additional 45° rotation. It results in the reflected light polarized in the horizontal plane and hence will be rejected by the input polarizer to allow only to pass the light in the vertical plane. This way an optical isolator allows light to be transmitted in one direction only and prevent any reflected light to avoid feedback problem.

Applications of Optical Isolator

Optical isolators are used in many applications in optical systems across industries, including telecommunication, optical fiber communication, health care, and laboratories. They are usually used in optical applications that require stable single optical frequency and low optical noise. Optical isolators are very reliable devices when used in:

  • Fiber optic amplifiers
  • Fiber optic ring lasers
  • Fiber optic links in CATV applications
  • High-speed and coherent fiber optic communication systems
  • Laser diodes
  • Gyroscopic systems
  • Optical modular interfaces

Apart from the above applications, single-polarization fiber optic isolators are used in a variety of mechanical control and testing applications in many industries.

At DK Photonics, we sell a wide range of optical isolators with very low insertion loss and excellent temperature stability. Some of the most popular ones are 1064nm High Power In-line Isolator, 1030nm High Power In-line Isolator, 1080nm High Power In-line Isolator, 1550nm High Power In-line Isolator, 2000nm High Power In-line Isolator, and many more for a variety of optical systems. We can also help you with your customized needs to meet your desired specification and quote a custom isolator for your specific industrial use. Contact us to know more about optical isolators and how we can help your industry with high-quality optical components.