[OPTICAL REVIEW Vol. 4, No. 1A (1997) 80-84]

Multimode Optical Fiber Demultiplexer-Star Coupler Using a Single Gradient-Index-Rod Lens and a Multi-Facet Grating

Takehiro FUKUSHIMA and Toyokazu SAKAMOTO

Department of System Engineering, Faculty of Computer Science and System Engineering, Okayama Prefectural University, 111, Kuboki, Soja, Okayama, 719-11 Japan

(Received June 28, 1996; Accepted September 9, 1996)

An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection grating is proposed to simultaneously realize functions of wavelength demultiplexing and optical signal distribution in a multimode optical fiber transmission system. We analyzed the demultiplexing characteristics and the tolerance of optical components using the ray trace method. This device can realize not only low loss optical signal distribution but also offers improved demultiplexing characteristics in comparison with the previously proposed demultiplexer-multiposition switch. The following characteristics are expected from the design using commercially available optical components: a working band of 0.64-0.88 μm, channel separation of 34-36 nm, 3 dB bandwidth of 27-28 nm, channel cross-talk of less than -40 dB and minimum excess insertion loss of 0.9-2.1 dB.

Key words : wavelength division multiplexing, wavelength demultiplexer, optical signal distribution, multi-function device, optical fiber array, gradient-index-rod lens, multi-facet grating