This paper introduces a novel 1×2 all-optical switch based on Tri-arm Mach-Zehnder (TaMZ) that uses an all-optical flip-flop (AOFF). The proposed switch is analytically modeled and simulation shows a marked improvement in signal on/off contrast ratio (CR) between two outputs over a larger range of control signal power compared to the existing symmetric Mach- Zehnder (SMZ) switches. In addition, TaMZ switch offers both broadcasting and complete switch-off capability, which further enhances the flexibility of the optical switching applications. The paper presents the principle of TaMZ-based switch and investigates theCRperformance. It is shown that theCRimprovement is more than 10 dB compared to conventional SMZ switch in a control signal power range of 20 dB.

Transmission of high-quality analogue sourced signals over copper or optical fibre links and networks demands a critical choice of modulation format to achieve both high performance and to avoid unnecessary bandwidth overhead penalties. Pulse time modulation (PTM) techniques are being increasingly employed to overcome many of the problems associated with traditional analogue and digital methods. Among the family of pulse time modulation techniques squarewave frequency modulation (SWFM) is particularly well suited to the transmission of high-quality wideband instrumentation and video signals, such as high definition TV, due to its attractive combination of performance and simplicity. This paper presents theoretical and practical aspects of SWFM and describes a number of experimental SWFM systems capable of transmitting signals from DC to 30 MHz.>