Abstract
The Kerr nonlinearity can be a key enabler for many digital photonic circuits as it allows access to bistable states needed for all-optical memories and switches. A common technique is to use the Kerr shift to control the resonance frequency of a resonator and use it as a bistable, optically-tunable filter. However, this approach works only in a narrow power and frequency range or requires the use of an auxiliary laser. An alternative approach is to use the asymmetric bistability between counterpropagating light states resulting from the interplay between self- and cross-phase modulation, which allows light to enter a ring resonator in just one direction. Logical high and low states can be represented and stored as the direction of circulation of light, and controlled by modulating the input power. Here we study the switching speed, operating laser frequency and power range, and contrast ratio of such a device. We reach a bitrate of 2 Mbps in our proof-of-principle device over an optical frequency range of 1 GHz and an operating power range covering more than one order of magnitude. We also calculate that integrated photonic circuits could exhibit bitrates of the order of Gbps, paving the way for the realization of robust and simple all-optical memories, switches, routers and logic gates that can operate at a single laser frequency with no additional electrical power.
Highlights
At the present time, fiber optics telecommunication nodes convert light into electrical signals with fast photodiodes to perform processing, routing, or storing of information
Some are still controlled by non optical inputs such as electro-optic modulators (EOMs), micro-electro-mechanical systems (MEMS) [3] or thermally tuned devices [4]
We introduce the quantity Pcoup because it has the same order of magnitude of the input power and, in a steady state, it can be measured as the difference between the input and the transmission in the input tapered fiber
Summary
Fiber optics telecommunication nodes convert light into electrical signals with fast photodiodes to perform processing, routing, or storing of information. This is an established technology; the increasing traffic on networks is approaching the limitation imposed by the double conversion of the signals from optical to electronic and back to optical again. This conversion requires an additional layer of complex, expensive and power-hungry devices such as lasers and electro-optic modulators (EOMs). When low operating power is required, resonant optical cavities can be used
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