Single-mode-fiber 1 × N directional coupler

We report the development of an adjustable single-mode-fiber multiterminal directional coupler that exhibits efficient coupling and uniform terminal output over a wide range of coupling coefficients. The device is made using a new technique that employs silicon V-groove substrates in the fabrication of arrays of evanescently coupled taps on single-mode fibers. The coupler is highly directional and polarization independent and exhibits excess loss as low as 0.09 dB per terminal in a 1 x 7 device. The fabrication technique may be extended to produce devices having large numbers of terminals. Applications include use in fiber data-bus systems and as a tapped delay line for broadband signal processing.