XGM) And Cross-phase Modulation Research Articles

High-repetition-rate femtosecond "OR" gate design in a differential SOA-MZI

In this article, an experimental investigation of a combined "OR" gate design reliant on a differential semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is presented. The suggested "OR" gate takes advantage of the cross-gain modulation (XGM) and cross-phase modulation (XPM) effects generated at the SOA-MZI outcome. Furthermore, the optical, electrical, and temporal categories are used for testing and analyzing the system's performance. This "OR" gate technology is very useful in numerous scenarios, especially in optical networking. Numerous factors, including extinction ratio (ER), beam quality factor, and optical and electrical spectra, are used for assessing the optical "OR" gate. With a beam propagation ratio (BPR) of less than 2.4 (M2<2.4), the "OR" gate design provides superb beam quality. The successful creation of the electrical "OR" transmission exhibits about sixteen harmonics with exceptional powers and substantial ERs. The last important phase in optical communications and network connectivity is pulse compression, which can increase the optical average power while enjoying the advantages of brief pulses. In fact, pulse compression combines the intense energy of an extensive pulse with the great accuracy of an extremely short pulse. The grating-fiber compressor approach is widely used to accomplish the pulse compressions. The combined "OR" output pulse, which has undergone pulse compression, has a duration of 50 fs at a wavelength of 1530 nm.

A simultaneous all-optical half/full-subtraction strategy using cascaded highly nonlinear fibers

Using non-linear effects such as cross-gain modulation (XGM) and cross-phase modulation (XPM) inside two highly non-linear fibres (HNLF) arranged in cascaded configuration, a simultaneous half/full-subtracter is proposed. The proposed simultaneous half/full-subtracter design is attractive due to several features such as input data pattern independence and usage of minimal number of non-linear elements i.e. HNLFs. Proof of concept simulations have been conducted at 100 Gbps rate, indicating fine performance, as extinction ratio (dB) > 6.28 dB and eye opening factors (EO) > 77.1072% are recorded for each implemented output. The proposed simultaneous half/full-subtracter can be used as a key component in all-optical information processing circuits.

A cascadable all-optical half-subtracter based on cross-modulation effects in a single highly nonlinear fiber (HNLF)

An all-optical half-subtracter is proposed based on harnessing of 3rd order (χ(3)) non-linear effects such as cross-gain modulation (XGM) and cross-phase modulation (XPM) inside a single highly non-linear finer (HNLF), which is capable of operating at 100 Gbps operating bit rate. The XGM effect occurrence in HNLF has been exploited for the implementation of both borrow logics \(\left( {A.\bar{B}\,\& \,\bar{A}.B} \right)\). Whereas, the difference output of proposed half-subtracter represented by \(A \oplus B\) logic is obtained from XPM process taking place on low-energy continuous-wave (CW) probe signal which is co-propagating with two high energy pump signals. The proposed half-subtracter can exhibit cascadability, owing to single wavelength centric nature of all the three logic functions generated such as \(A.\bar{B}\), \(\bar{A}.B\,\&\,A \oplus B\). The proposed half-subtracter functionality is verified through inspection of temporal waveforms and eye diagrams of achieved output logic functions. Further, dependence of output function’s Q-factor and Extinction Ratio (dB) values on following parameters: pump/data signal powers (PA\(\&\)PB), CW probe power (PCW) and choice of CW probe operating wavelength (λCW) is also investigated and discussed. In the final stages, an investigation has been carried out by implementing secondary logic functions \(\left( {\left( {A.\bar{B}} \right).\bar{C},\,\left( {\overline{{A.\bar{B}}} } \right).{\text{C}}\text{,}\,\left( {\bar{A}.B} \right).\bar{C},\,\left( {\overline{{\bar{A}.B}} } \right).C,\,\left( {\overline{A \oplus B} } \right).C\,\& \,\left( {A \oplus B} \right).\bar{C}} \right)\) to examine the cascade-ability characteristics of the proposed half-subtracter. It has been shown by calculating temporal waveforms and eye diagrams of secondary logic functions such as \(\left( {A.\bar{B}} \right).\bar{C},\,\left( {\overline{{A.\bar{B}}} } \right).{\text{C,}}\,\left( {\bar{A}.B} \right).\bar{C},\,\left( {\overline{{\bar{A}.B}} } \right).C, \left( {\overline{A \oplus B} } \right).C\,\& \,\left( {A \oplus B} \right).\bar{C}\) that proposed cross-modulation effects in HNLF based half-subtracter is indeed cascadable.

Simultaneous NRZ-to-RZ format conversion and one-to-six error-free channel multicasting using a single pump in a highly nonlinear fiber

We demonstrate simultaneous 10-Gb/s NRZ-to-RZ format conversion and multicasting from one to many data channels in a highly nonlinear fiber (HNLF) with only a single pump. Functionalities are achieved based on various nonlinear effects, such as four-wave-mixing (FWM), cross-gain-modulation (XGM) and cross-phase-modulation (XPM) between the pump channel and the NRZ data channel. Up to five and six converted data channels are error-free (10(-9) BER) as the wavelength spacing between the pump and the NRZ signal is set to 0.4-nm and 0.8-nm, respectively.

Theoretical Study of Assist Light Effect on XGM and XPM-Based Wavelength-Conversion Using SOAs

For wavelength conversion based on cross-gain modulation (XGM) and cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), a CW assist light is quite effective for acceleration of carrier recovery and reduction of pattern effects. We theoretically study assist light conditions both for XGM- and XPM-based wavelength conversion by numerically simulating eye-diagrams. Taking into account the spatial and temporal variations of carrier density along the SOA length, we successfully clarify the dependences of wavelength, power, and propagation direction of the assist light, and reveal the principal difference of response characteristics between XGM and XPM depending on carrier modulation.

Wavelength conversion of SCM signals using semiconductor optical amplifiers: theory, experiments, and applications

In this paper, we deal with the subject of cross-gain modulation (XGM) and cross-phase modulation (XPM) semiconductor optical amplifier-based wavelength conversion of optical channels carrying subcarrier multiplexing signals in a comprehensive way. The equations and models that describe the conversion process and the resulting harmonic and intermodulation distortions are obtained showing the superior performance of XPM over XGM in terms of secondand third-order distortion and contrast ratio. Experimental results for XGM-based wavelength conversion that confirm the results predicted by our theoretical models are presented, and finally, we consider the specific application of wavelength conversion of optical channels carrying full frequency plans such as that of cable television applications.

Theoretical study of frequency chirping and extinction ratio of wavelength-converted optical signals by XGM and XPM using SOA's

We develop a complete large-signal dynamic model of semiconductor optical amplifier (SOA)-based wavelength converters using cross-gain modulation (XGM) and cross-phase modulation (XPM). The large-signal dynamic model has been implemented using the modified transfer matrix method (TMM). This model takes into account longitudinal variations of carrier-induced refractive index, n-parameter, internal reflection, photon density, and amplified spontaneous emission noise at each small section. Therefore, we can accurately estimate frequency chirping, optical pulse patterns, and the extinction ratio as well as the dynamic characteristics of SOA's. Frequency chirping and the extinction ratio have been calculated for various parameters such as signal power and wavelength, CW power and wavelength, and facet reflectivity. Modulation bandwidth, defined by the 3-dB drop as the eye opening ratio (EOR) is investigated with current density, confinement factor, and cavity length.

All-optical wavelength conversion at bit rates above 10 Gb/s using semiconductor optical amplifiers

This work assesses the prospects for high-speed all-optical wavelength conversion using the simple optical interaction with the gain in semiconductor optical amplifiers (SOAs) via the interband carrier recombination. Operation and design guidelines for conversion speeds above 10 Gb/s are described and the various tradeoffs are discussed. Experiments at bit rates up to 40 Gb/s are presented for both cross-gain modulation (XGM) and cross-phase modulation (XPM) in SOAs demonstrating the high-speed capability of these techniques.

Tunable optical wavelength converters with reconfigurable functionality

We propose novel circuits for tunable all-optical wavelength converters with reconfigurable functionality. Circuits for wavelength converters based on cross-gain modulation (XGM) and cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs) are considered, for both copropagating and counterpropagating pump and probe signals. The circuits use arrayed-waveguide grating multiplexers (AWGMs) to filter and route signals in and out of the SOAs. The AWGM's minimize the component count in the circuits and may lead to future integration of wavelength converters. We experimentally demonstrate a XGM wavelength converter with copropagating pump and probe signals and report its bit-error-rate (BER) performance at 2.5 Gb/s.