Operating Curves for Optical Bistable Devices

P. Wheatley, John Edwin Midwinter

A graphical method is described where-by the important steady state and dynamic responses of an optical bistable device can be viewed simultaneously. This results in a set of ‘operating curves’ which indicate how well an optical bistable device satisfies the requirements to perform a particular logic function. The operating curves may be used to find the optimum conditions to perform a function and they also show how resilient this point is in the presence of fluctuations in operating conditions.

A. Daunois, J.‐Y. Bigot

P. J. Wheatley, John Edwin Midwinter

Optical bistable devices [1] are being developed with a view to their use as logic gates in optical processors [2]. The response of an optical bistable device is strongly nonlinear and once a device has been fabricated, its behaviour as a logic gate can still be modified to a large extent by the variation of certain parameters used to bias the device, Important responses include the device’s fanout potential, its switching speed and the contrast between its high and low output levels. Because of the complexity of the behaviour, it can be difficult to see how one response varies as another is improved. The method of ‘operating curves’ explained here allows a system designer to see how optimum performance may be attained.

P. W. E. Smith

P. Wheatley, John Edwin Midwinter

There is much interest in the use of optical bistable devices as logic gates for optical processors. Although desirable properties have been reported, it is difficult to see how these are offset by less desirable ones. All properties of the device can be controlled to a certain extent, principally by the bias conditions. Here we show how steady state and dynamic responses vary simultaneously with these parameters. These operating curves can be used to see the capabilities of a device or to choose the optimum bias conditions.

Shenping Li, Zhonghong Yan, Yizhou Zhang