Implementation of optical hybrids
For laboratory purposes, the 90° optical hybrid has traditionally been constructed using two 50/50-beam splitters and two beam combiners, plus one 90° phase shifter (See Figure 2). These optical hybrids can be implemented using all-fiber, planar waveguide technologies or free-space technology.
A 90° optical hybrid can be based on a Michelson interferometer or Michelson interferometerstructure (See Figure 2-3). The Michelson interferometer principle has been proven and tested in free-space bulk optics and optical component manufacturing. Free-space bulk optics is used in many optical components, such as circulators, polarization beam combiners, wavelength lockers, dispersion compensators, optical interleavers and Optical DPSK demodulators, to the fiber-optic communication industry. Bulk optics based devices can be coupled to commercially available fiber collimators.
September 30, 2011