Wavelength dependence of 3*3 fibre couplers for gyro applications

The wavelength dependence of the scattering matrix of a 3*3 fibre coupler for gyroscope applications is investigated. A new method, using only simple intensity measurements is developed, yielding the amplitudes as well as the phases of the scattering matrix including the wavelength dependence of the three coupling lengths. Excellent symmetry properties of the investigated 3*3 coupler have been found.