Search

A four-channel phased-array wavelength demultiplexer with a flattened wavelength response has been realised for the first time in InP/InGaAsP at 1.54 mu m by employing multimode output waveguides. The device has 2 nm channel spacing and a flat response (within 1 dB) of 17 nm. >

A new method for the fabrication of a singlemode fibre wavelength independent Y-junction is described; through asymmetrically tapering a pre-assembled Y-junction precursor, the splice point is drawn into the waist region of the device and low-loss is ensured. The lowest loss and flattest wavelength response for such a device is reported.

The paper is confined to a discussion of the mechanical limits imposed on magnetic recording heads by the required performance specification. The performance criteria of a multi-track head are normally: sensitivity and the variation in sensitivity between tracks, the short wavelength response, high-frequency losses, bias sensitivity, and cross-talk between adjacent tracks. The manufacturing problems associated with multi-track heads are discussed in relation to the effects of mechanical variations on the head performance.

The fabrication and performance of a stable single-mode transmissive 8×8 star coupler is described. The device exhibits very low excess loss (0.13 dB), good coupling uniformity (0.73 dB) and low near-end crosstalk (>64 dB). The star coupler is fabricated from eight lengths of single-mode fibre, by forming 3 dB fused coupling regions between appropriate fibre pairs. A Table of insertion loss measurements is presented, together with graphs showing the wavelength response between 1.2 and 1.7 μm.