Compact optical circulator for optical fiber transmission.

Area of Science:

• Optoelectronics
• Photonics
• Materials Science

Background:

• Optical circulators are crucial components in optical transmission systems.
• Existing circulators may face limitations with multi-mode fibers that do not conserve light polarization.
• Near-infrared (near-IR) radiation is widely used in optical communication.

Purpose of the Study:

• To develop a novel optical circulator optimized for near-IR radiation.
• To enable robust bidirectional transmission in systems with polarization-sensitive fibers.
• To achieve low insertion loss for various light polarization states.

Main Methods:

• Fabrication of a 45-degree Faraday rotator utilizing a Yttrium Iron Garnet (YIG) single crystal.
• Integration of two Glan-Taylor prisms for polarization control.
• Configuration with four nonreciprocal and two reciprocal ports.

Main Results:

• The developed optical circulator exhibits four nonreciprocal and two reciprocal ports.
• Insertion losses of 1.5-2.3 dB were achieved among the four nonreciprocal ports at a 1.32-micrometer wavelength.
• An estimated insertion loss of 0.66 dB was obtained for nonpolarized light using one nonreciprocal and one reciprocal port at 1.32 micrometers.

Conclusions:

• The developed optical circulator effectively functions for near-IR radiation in optical transmission systems.
• The circulator's design, using reciprocal ports, successfully accommodates bidirectional transmission with multi-mode fibers, regardless of light polarization.
• Low insertion losses demonstrate the device's efficiency and potential for practical application in optical communication networks.