Home > Oz Optics polarisation dependent and independent isolators available from Warsash Scientific

Oz Optics polarisation dependent and independent isolators available from Warsash Scientific

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article image Oz Optics isolator

Oz Optics fibre optic isolators are available from Warsash Scientific . It has the following features:

  • >10W optical power handling capability
  • Polarisation sensitive and insensitive versions
  • Product offerings over 488 nm to 1600 nm wavelength range
  • High isolation levels and low return loss
  • Low insertion loss and polarisation dependent losses
  • Different compact sizes, including miniature packaged versions
  • Stable designs

Oz Optics fibre optic isolators can be used in the following applications:

  • High power laser to fibre coupling systems
  • Optical amplifiers
  • CATV systems

OZ Optics offers a line of fibre pigtailed isolators for wavelengths ranging from 488nm to 1650nm. These isolators combine a free space Faraday rotator with polarising optics to provide up to 60 dB of isolation and high power handling with minimum losses. OZ Optics isolators are manufactured using their tilt alignment technique. Input light from an optical fibre is first collimated and then transmitted through the isolator optics. A focusing lens on the output side of the isolator then couples the light back into the output fibre. This method allows OZ Optics to offer isolators capable of handling up to 10 watts of optical power through singlemode fibres.

Isolators are offered in two different versions, polarisation dependent and polarisation independent. Both block any returning light irrespective of the input polarisation. However, the insertion losses of polarisation dependent isolators depend on the input polarisation, while for polarisation independent isolators the insertion losses are constant.

Polarisation dependent isolators are simpler in construction. They are suitable for polarisation maintaining fibre applications and for applications where an input free space beam of constant polarisation enters the Faraday optics. In either case, linearly polarised light from the source or polarisation maintaining fibre is aligned with the transmission axis of the isolator. However, these isolators are not recommended for applications using standard singlemode fibres, as these fibres do not maintain polarisation. Instead when polarised light is launched into singlemode fibres, any bends or stresses in the fibre changes the polarisation state of the light travelling through the fibre. As a result, transmission through a polarisation dependent isolator varies with any bending of the fibre or changes in temperature.

In contrast, a polarisation independent isolator first splits the light into separate polarisations and isolates each beam separately. The two beams are then recombined and transmitted through the output fibre. This method ensures low losses irrespective of the input polarisation state and hence polarisation independent isolators with singlemode fibres are recommended. However, polarisation independent isolators are not necessarily available for all wavelengths or power levels.

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