All-optical integrated micro logic gate

Abstract

In this paper we present a novel approach for realizing an integrated all-optical logic gate. The basic principle is based upon stimulated emission process generated in an active gain medium while special interferometric photonic wave-guiding structure allows the realization of an integrated micro scale device. The operation rate of the proposed device structure can theoretically reach tens of Tera-Hertz.

Introduction

Realizing optical integrated circuits is an important task due to its scientific merit as well as its industrial applicability. The aim of this research is to generate all-optical integrated processing devices as modulators and logic gates capable of operating at high processing rates as well as being integrated with optics communication modules [1], [2], [3], [4], [5], [6].

The ability to carry out concurrent large-scale on-chip information processing and multi-channel communication is valued in information technology. All-optical systems may carry out these tasks at high speeds or rates far exceeding electronic counterparts. Typically light beams that are to be processed by an all-optical device have a non-linear interaction with the electronic subsystem of the device's medium, so as to produce a certain non-linear effect (e.g. two and four waves mixing, frequency doubling, parametric oscillation, etc.) on utilization of which the operation of the particular device is based. Accordingly, all-optical devices tend to use media with a large non-harmonicity of electronic oscillations. Typically all-optical devices also tend to require intense illumination and a large interaction length for proper operation.

In this paper we propose a novel approach for developing integrated all-optical logic gates capable of having nano and micro scale dimensions as well as ultra fast operation rates. The concept is based upon stimulated emission in an optically pumped gain medium [7]. The technique utilizes the dependence of a signal propagating through a stimulated emission medium (herein called the gain medium) on gain. This dependence is typically non-linear with respect to the gain. The idea behind the proposed operation principle is to use photonic input signals to control the gain of the medium since the gain depends on the number of photons in the medium. Increasing the number of photons reduces the gain. A reference beam that passes through the gain medium is coupled to the output of the device. Since the amplification of the medium is directly proportional to the logic inputs, a Boolean logic operation may be realized at the output of the device. Because stimulated emission is involved, the response rate of operation mechanism is very short (an immediate response).

The novelty of this paper includes also the design of a special interferometric photonic wave-guiding structure, which is a major component in the realization of an integrated micro scale logic device.

In Section 2 we present the operation principle. Section 3 discusses the fabrication process of the device whose operation principle is being validated in Section 4. The paper is concluded in Section 5.