An optical threshold function based on polarization rotation in a single semiconductor optical amplifier

R Geldenhuys,J J Vegas Olmos,G D Khoe,F W Leuschner,H J S Dorren,Y Liu

doi:10.1364/oe.15.007275

Abstract

Optical threshold functions are a basic building block for all-optical signal processing, and this paper investigates a threshold function design reliant on a single active element. An optical threshold function based on nonlinear polarization rotation in a single semiconductor optical amplifier is proposed. It functions due to an induced modification of the birefringence of a semiconductor optical amplifier caused by an externally injected optical control signal. It is shown that switching from both the TE to the TM mode and vice versa is possible. The measured results are supported by simulation results based on the SOA rate equations.

Highlights

Optical threshold functions are a basic building block for optical signal processing as they provide an all-optical way of implementing simple decisions in various applications
Optical threshold functions are a basic building block for alloptical signal processing, and this paper investigates a threshold function design reliant on a single active element
An optical threshold function based on nonlinear polarization rotation in a single semiconductor optical amplifier is proposed

Summary

Introduction

Optical threshold functions are a basic building block for optical signal processing as they provide an all-optical way of implementing simple decisions in various applications. The threshold function can be extended to form an arbiter using a laser neural network, used for all-optical buffering in [3] One disadvantage of this coupled ring laser design is that it uses two active elements, semiconductor optical amplifiers (SOAs), increasing the footprint of the setup and its power consumption. Another limitation is that the injected optical power must be sufficient (e.g. 8.2dBm as described in [3]) to suppress one lasing mode before the other can start lasing. As the optical power in the SOA increases, the saturation-induced phase difference alters the intensity of the light that is output from the SOA

Operating principle

Nonlinear polarization rotation

Experiment and results

Theoretical analysis

Conclusions