LAUSR

Abstract An asymmetric Mach-Zehnder interferometer (AMZI) which comprised a variable optical attenuator (VOA), a thermo-optic phase modulator (TOPM) and a delay line of 740 ps was designed and fabricated using silica-based planar lightwave circuit technology. Two identical AMZI chips were connected in series to demonstrate the single photon interference in the middle pulse. The experimental results showed the TOPM can modulate the phase difference between the double pulses. The single photon interference visibility was dependent on the temperature and the polarization of the input light. The observed maximum visibility was 98.38% when the temperature of temperature controller (TEC) was 10 °C. And the interference visibility was dependent on the polarization of the input light. The AMZI could form the basis of the passive decoder in the future quantum cryptography systems.