SINGLE-MODE FUSED BICONICAL COUPLER OPTIMIZED FOR POLARIZATION BEAMSPLITTING

A single-mode fused biconical coupler for polarization beamsplitting is described. In the coupling region standard communication fibers are used. The output fibers are polarization maintaining. To stop the coupler drawing process accurately, the degree of polarization is measured during the drawing and is used as criterion. Losses of 0.2 dB are typical and a minimum extinction ratio of -27 dB is achieved. A usable spectral window as broad as 17 nm with an extinction ratio smaller than -15 dB for both output fibers is obtained. Any specified wavelength for the minimum of the extinction ratio is reached within +/- 3 nm.