Single-mode fibre coupler with the 3-dB splitting ratio simultaneously at 0.83 and 1.3 μm

The problem of designing a two-wave single-mode-fibre 3-dB coupler is considered. The method is proposed for adjusting the parameters of the coupler for simultaneous use of radiation at 0.83 and 1.3 μm in one fibre interferometer. The dependence of the coupling efficiency on the wavelength is studied experimentally for different angle mismatches of fibres in the coupler. The results of experiments and numerical calculations are presented.