Method of developing all-optical trinary JK, D-type, and T-type flip-flops using semiconductor optical amplifiers

Abstract

To meet the demand of very fast and agile optical networks, the optical processors in a network system should have a very fast execution rate, large information handling, and large information storage capacities. Multivalued logic operations and multistate optical flip-flops are the basic building blocks for such fast running optical computing and data processing systems. In the past two decades, many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitations because of the low switching response of active devices. The frequency encoding technique has been used because of its many advantages. It can preserve its identity throughout data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. The action of polarization-rotation-based very fast switching of semiconductor optical amplifiers increases processing speed. At the same time, tristate optical flip-flops increase information handling capacity.

All-optical binary logic unit (BLU) using frequency encoded data

“…One of the important techniques of frequency conversion by SOA is the exploitation of non-linear rotation of the state of polarization of the probe beam due to optically induced refractive index change in a bulk SOA in the presence of highly intense pump beams. In this technique interaction of two intense pump beams 'A' and 'B' with the probe beam in the active medium of the SOA induces nonlinear refractive index change which in turn modify the intensity of probe beam as well as its state of polarization (SOP) [7][8][9][10][11][12][13]. Thus the 'TE' and 'TM' modes of the linearly polarized probe beam 'X' of frequency 'm' after passing through the active medium of the SOA suffers phase change, and consequently, the SOP of the output beam with respect to the input probe beam also changes.…”

“…Therefore, the TE and TM components of the probe beam propagate with unequal velocities, and they recombine at the port-2 with different phase shifts and different optical gains. In the presence of pump beam of power about 0.4 mW or more, due to phase change of 180°between TE and TM modes of the beam, they interfere destructively, and consequently no beam appear at the at port-2, and obviously maximum power will develop at port-1 [13][14][15][16][17][18]. If A (z, t) represents the electric field of the propagating probe beam at a distance 'z' within the active medium of the SOA along its axis of propagation at 't', then on the basis of time rate equation model of SOA [15], then power and phase associate with each mode of propagating field can be represented by the Eqs.…”