Sagnac-loop phase shifter with polarization-independent operation
  A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. A transverse mode electro-optic modulator using lithium niobate is placed in a Sagnac-like loop containing Faraday rotators. This direction-dependent polarization rotation in the loop is combined with a Mach-Zehnder interferometer to form an optical switch with an on/off contrast of 96% and a switching time of 1.6 ns. 
Tien Tjuen Ng, Darwin Gosal, Antia Lamas-Linares and Christian   Kurtsiefer