Optical Memories

Yoshito Tsunoda

Y. Liu, M.T. Hill, Daan Lenstra +4 more

An all-optical memory with three states is presented. The optical memory is realized from three-coupled identical nonlinear polarization switches. The state of the optical memory is determined by the wavelength of the memory’s output light. In each state, only one wavelength is dominant. The concept is explained and experimental results are presented that demonstrate that a contrast ratio of over 20 dB and a switching power of around 8 dBm can be obtained. This concept can be extended for an all-optical memory with a large number of states, which is crucial to realize 1×N all-optical packet switches.

Keishi Habara

Abstract To realize a high‐speed time division optical switching network, optical bistability devices including optical memory are important. In this paper, a bistable laser‐diode memory made of an APD, an LD and an optical feedback circuit is studied from the point of low set power and high speed. To attain a low set power, the effect of spontaneous emission of an LD cannot be neglected. Therefore, the input and output characteristics of an optical memory are studied including the spontaneous emission coefficient. Next, the response speed at a low input power is studied and the relationship between the response speed and the optical memory design parameters is derived. The input‐output characteristics and the response speed are verified with an experimental circuit. Finally, a high‐speed optical memory with a low set power is fabricated. The results of operating experiments of optical memories in an optical switching network are described.

Paul W. Nutter

Alistair J. Poustie, Anthony E. Kelly, Keith J. Blow +1 more

The function of ‘memory’ is one of the key building blocks to implement advanced information processing in future ultrahigh-speed photonic networks. Previously, we have described an all-optical regenerative memory in which stable storage of data is obtained for several hours [1]. In addition, the memory architecture provides amplitude restoration for the stored pulses and the ability to set a threshold storage level [2]. Here we demonstrate an important extension to this design which not only allows optical pulses to be written to the memory but also permits optical pulses to be selectively read from storage. This additional capability greatly extends the usefulness of the memory as a sub-system in more complex processing operations [3]. To achieve the ‘read’ function we incorporate a third nonlinear optical switching element (TOAD/SLALOM [4,5]) to act as an all-optical modulator for the data stored in the regenerative memory.

立野 公男