New wideband and temperature-stabilized optical isolator for wavelength division multiplexing fiber transmission system

摘要

In recent years, growing attention is being focused on wavelength division multiplexing optical communication system as a promising means of mass-scale communication. To realize these systems, wideband and temperature-stabilized optical isolators are essential, which in turn require Faraday rotators capable of ensuring a Faraday rotation stable against wavelength and temperature variation. A new wideband and temperature-stabilized optical isolator for 1.55 $mu@m wavelength has been developed using Bi- substituted holmium-ytterbium iron garnet (HoYbBiIG) single crystal as a Faraday rotator. The optical isolator features 0.34 $mu@m bandwidth, less 0.6 dB insertion loss and over 37 dB backward loss at a wavelength of 1.55 $mu@m throughout the temperature range from $MIN@10 to 60 degrees C. The Faraday rotation and optical absorption loss of HoYbBiIG have been investigated in the near-IR wavelength region. The specific Faraday rotation of Ho$-0.85$/Yb$-1.02$/Bi$- 1.13$/Fe$-5$/O$-12$/ is about $MIN@767 deg/cm at $lambda $EQ 1.55 $mu@m. The Faraday rotation wavelength and temperature characteristics of HoYbBiIg crystals are also discussed. These result indicate that the Bi-substituted holmium- ytterbium iron garnet single crystals realize a high Faraday rotation stability against temperature and wavelength in the near IR region.