Abstract: A coherent detector which is insensitive to signal or polarization state may be assembled using a fused optical fibre multiport constructed from five optical fibres. The fibres are fused in a circularly symmetric arrangement, then tapered until power injected into any input is equally distributed to all outputs. Reference signals are injected into adjacent inputs and the signal to be detected into a signal adjacent one of the reference inputs.

Abstract: A DFB laser is provided with a top electrode divided symmetrically into two or three in-line separate elements through which a bias current is applied with a symmetrical distribution and through which a modulation current is applied with an antisymmetric (push-pull) distribution.

Abstract: An opto-electronic switch which shows a good signal rejection ratio between modes is also of particularly small dimensions. The switch comprises a semiconductor laser 1 having four contacts 12, 12', 13, 13' which provide gain guiding under two stripe windows 18, 19. By varying the bias currents supplied to the individual contacts 12, 12', 13, 13', or inputting optical control signals to the waveguiding channels under the stripe windows 18, 19, different configurations of optical output from the laser 1 can be achieved. The two contacts, 12, 12' and 13, 13', associated with each stripe window 18, 19 are effectively a signal stripe contact with a discontinuity. It is thought that diffractive transverse coupling at the discontinuity allows the use of a shorter device than in known directional switches. With feedback, the switch operates as a memory device. The switch finds particular application in optical communications, for instance in signal routing.

Abstract: A frameless goggle construction including an elongated lens structure having opposed ends formed of a generally planar, semi-rigid, transparent sheet of plastic deformed about its minor dimension to be configured as a simple curve with convex and concave sides. The sheet rigidity is such that the lens structure may flex to move the ends closer to or further from each other and the periphery of the concave side mounts a layer of soft resilient cushioning material of substantial thickness adapted for cushioned contact with and conformance to the face of a wearer of a goggle. An elongated strap is connected to the ends of the lens structure to secure the goggle to the head of the wearer and to provide a face conforming force to the lens. The lens structure is antifogging and formed of a non-rigid spacer sandwiched between inner and outer lenses with air flow passages formed in the spacer and inner lens.