G. Bonfrate et al., Asymmetric Mach-Zehnder germanosilicate channel waveguide interferometers for quantum cryptography systems, ELECTR LETT, 37(13), 2001, pp. 846-847
Asymmetric Mach-Zehnder channel waveguide interferometers possessing a 1.1
ns delay in one of the arms were fabricated using dame hydrolysis deposit;i
on of silica glass on silicon. Two modules were combined to form a single t
ime-division interferometer for optical pulses. The composite interferomete
r exhibited a high fringe contrast ratio of 1:200 making ii eminently suita
ble for use in compact, low error-rate quantum cryptography systems.