SOA-based devices for all-optical signal processing

Abstract

Fast all-optical signal processing functions realized with non-linear semiconductor optical amplifiers, particularly those associated to interferometric stmchwes, are presented. Different integration schemes are compared with criteria concerning device insertion in systems. IntroductionDevelopment of all-optical and wavelength domain multiplexing (WDM) networks requires numerous and diversified optical processing functions like wavelength conversion, regeneration, addkdrop, time domain multiplexing or logic functions. A fast non-linear element is necessiuy to realize such functions. The SOA (Semiconductor Optical Amplifier) is a particularly good candidate thanks to its compactness, its low consuming operation, its thermal stability and its non-linear properties: with reasonably moderate input optical and electrical powers, SOA can [1,2]. F~' i s inlrhsic'ally fast and can simulta: neously act on several WDM channels, but requires a quite complex pumping scheme to ensure polarization independence and a large wavelength span operation. The XGM scheme can be polarization independent, operate on a wide wavelength span and have a large input to be eakeeted befoga transmission a ; a cascade, for example thanks to a fiber Bragg grating [31.€ina\ly, the XPM is usully used with an interferometric stmcme in order to extract an amplitude modulated signal. For this reason, XPM devices present the highest non-linearity degree, made not only of the non-linear SOA but also of the nonlinear interferometer: this makes very functional and flexible smctllres with the particularity to be able to re-distribute the noise and thus to regenerate the signals. In this context we will focus on SOA-based interferometric devices. The principles and the achievable functions with such stmctures will be first presented, with a particular interest for regenerative devices. Then, we will present different SOAbased interferometer intezration schemes and their capability for an easyinsertion in real systems. SOA-based Interferometers: principles and functloasThe particularity of the SOA-based devices using an interference scheme is their capacity to regenerate the signals thanks to their sinusoidal transfer function. In these devices, the reGeneration is often based on wavelength conversion. In these cases, an optical clock can be introduced and become the converted signal to realize complete (3R) signal regeneration (Reamplifying, Reshaping, Retiming). In the semiconductor ultrafast nonlinear interferometer (LN) [4], the probe signal (clock signal) is split into two orthogonally polarized pulses, which are separated by several picosecond (typically twice the data pulse width and lower than the bit duration) before to go through a SOA whose gain and indcx are modulated by the data signal. The delay between both probe pulses is then reversed and the two compo-"enti k m b m r d bcforc pa,smd through a pdar-12cr. Cascaded 40 Gb 3 3R dair regrncratlon has been Ehoun with this d e \ w drm.m,lratm~ 2000 ~ ~ ~~~ ~~~~ ~~ ~~~~ ~~~~~ ~~ ~.., . .~~~ I km tra...

On the output characteristics of a semiconductor optical amplifier driven by an ultrafast optical time division multiplexing pulse train

“…It is also assumed that the polarization of the input light is maintained linear during propagation through the SOA, which is considered to be polarization independent, since the commercial availability of SOAs with polarization sensitivities below 0.5 dB justifies to ignore this parameter. Given also that the residual facet reflectivities in real SOA devices have been dropped well below 1 Â 10 À5 [4] and the associated gain ripple values have been reduced to less than 0.3 dB, it is permissible to leave them out and disregard any lasing properties. Finally, it is assumed that the SOA takes the form of a traveling wave amplifier whose active region dimensions are such that it supports only a single waveguide mode, and that it behaves as an isotropic device, which in turn allows to treat the susceptibility tensor as scalar [14] and greatly simplify the theoretical analysis that follows.…”

“…Thanks to the remarkable progress that has been achieved in this field, SOAs are commercially available devices and possess several important properties, such as fast and strong nonlinearities, low power consumption, short latency, thermal stability, wavelength flexibility, large dynamic range, short response time, broadband and versatile operation and capability of large-scale integration with the subsequent attractive features of compactness, increased reliability and cost reduction [4]. These practical advantages have rendered SOAs indispensable elements for performing a wide set of all-optical signal processing functions, as for example wavelength conversion, demultiplexing, regeneration, Boolean logic, detection and sampling [5][6][7], which are required in order to avoid the cumbersome and power-consuming optoelectronic conversions and fully benefit from the high transmission capacity of lightwave networks [8].…”

All-optical flip-flop based on coupled SOA-PSW

“…The intensity, frequency, phase and polarization state of the incoming optical signals can be modulated by using nonlinear effects, which can achieve wavelength conversion, logic gates [1,3], signal regeneration, and other all-optical signal processing functions [2]. The implementation of the flip-flop [3] in this paper is based on semiconductor optical amplifiers (SOAs).…”

On the Feasibility of 320 Gb/S All-Optical and Gate Using Quantum-Dot Semiconductor Optical Amplifier-Based Mach-Zehnder Interferometer

“…In particular the AND gate is indispensable for achieving this goal as it is involved in the accomplishment of numerous tasks in the optical domain both in fundamental and system-oriented level, such as buffering [2], address comparison [3], add-drop multiplexing [4], packet clock and data recovery [5], packet header and payload separation [6], binary pattern recognition [7], binary counting [8], analog-to-digital conversion [9], digital encoding and comparison [10], data regeneration [11], waveform sampling [12], half addition [13], multiplication [14], construction of other logic gates [15] and of combinational logic circuits [16]. Given its important, multi-lateral role the AND gate has attracted intense research interest and among the technological options that exist for its implementation those that exploit a semiconductor optical amplifier (SOA) are well established [17]. In fact, besides being employed for classical applications such as signal generation [18], amplification [19] and modulation [20], SOAs have also demonstrated their potential as nonlinear switching elements for performing all-optical AND logic, either as stand-alone entities [21][22][23][24][25][26][27] or incorporated in an interferometric configuration [28][29][30][31][32].…”