The application of SOA for dispersion management of 2D-WH/TS codesin incoherent OCDMA system

In high data rate optical fibre communication networks, dispersion phenomenon plays a pivotal role. It is important to investigate the dispersion effects in a multi-wavelength picosecond optical code division multiple access (OCDMA) system. This research is focused on the analysis of the effects of fibre dispersion on the OCDMA autocorrelation; and how these effects can be resolved in a tuneable way so that the originally recovered OCDMA autocorrelation function at the decoder receiver can be revived without further manual adjustment of fibre (SMF-28) cable lengths.;The environmental effects and the subsequent mitigation process are also investigated further in this research. The chirp in OCDMA is examined experimentally and analytically in an initiative to find the more in-depth understanding of finely tuneable chromatic dispersion (CD) compensation technique in a coarsely compensated link by using semiconductor optical amplifier (SOA). A practical investigation was carried over a partially CD compensated 17 km bidirectional testbed between the University of Strathclyde and the University of Glasgow to perform the fine-tuning of CD adjustment using SOA.;A 19.5 km SMF-28 fibre spool was also used in an environmental chamber to investigate the temperature induced dispersion effects and subsequent mitigation. The tuneable dispersion compensation measures are vital to ensure the high data rate optical communication using an all-optical approach in future data network end-points where the advantages of ultra-high speed optical communication bandwidth are at present disrupted due to opto-electronic conversions commonly known as 'electronic bottlenecks'.In high data rate optical fibre communication networks, dispersion phenomenon plays a pivotal role. It is important to investigate the dispersion effects in a multi-wavelength picosecond optical code division multiple access (OCDMA) system. This research is focused on the analysis of the effects of fibre dispersion on the OCDMA autocorrelation; and how these effects can be resolved in a tuneable way so that the originally recovered OCDMA autocorrelation function at the decoder receiver can be revived without further manual adjustment of fibre (SMF-28) cable lengths.;The environmental effects and the subsequent mitigation process are also investigated further in this research. The chirp in OCDMA is examined experimentally and analytically in an initiative to find the more in-depth understanding of finely tuneable chromatic dispersion (CD) compensation technique in a coarsely compensated link by using semiconductor optical amplifier (SOA). A practical investigation was carried over a partially CD compensated 17 km bidirectional testbed between the University of Strathclyde and the University of Glasgow to perform the fine-tuning of CD adjustment using SOA.;A 19.5 km SMF-28 fibre spool was also used in an environmental chamber to investigate the temperature induced dispersion effects and subsequent mitigation. The tuneable dispersion compensation measures are vital to ensure the high data rate optical communication using an all-optical approach in future data network end-points where the advantages of ultra-high speed optical communication bandwidth are at present disrupted due to opto-electronic conversions commonly known as 'electronic bottlenecks'

Recent advances in all-optical signal processing for performance enhancements of OCDMA interconnects

The demand for data rates increases presents a great technological challenge to the well-established CMOS electronics. As a result, the electronic signal processing in optical interconnects became the stumbling block in supporting these growing demands. In this paper we will discuss and demonstrate our recent results which enable to overcome some of the challenges in OCDMA-based interconnects via implementation of silicon photonics

Photonic platform and the impact of optical nonlinearity on communication devices

It is important to understand properties of different materials and the impact they have on devices used in communication networks. This paper is an overview of optical nonlinearities in Silicon and Gallium Nitride and how these nonlinearities can be used in the realization of optical ultra-fast devices targeting the next generation integrated optics. Research results related to optical lasing, optical switching, data modulation, optical signal amplification and photo-detection using Gallium Nitride devices based on waveguides are examined. Attention is also paid to hybrid and monolithic integration approaches towards the development of advanced photonic chips

Application of semiconductor optical amplifier (SOA) in managing chirp of optical code division multiple access (OCDMA) code carriers in temperature affected fibre link

Chromatic and temperature induced dispersion can both severely affect incoherent high data rate communications in optical fiber. This is certainly also true for incoherent Optical Code Division Multiple Access (OCDMA) systems with multi-wavelength picosecond code carriers. Here, even a relatively small deviation from a fully dispersion compensated transmission link can strongly impact the overall system performance, the number of simultaneous users, and the system cardinality due to the recovered OCDMA auto-correlation being strongly distorted, time-skewed, and having its Full Width at Half Maximum (FWHM) value changed. It is therefore imperative to have a simple tunable means for controlling fiber chromatic or temperature induced dispersion with high sub-picosecond accuracy. To help address this issue, we have investigated experimentally and by simulations the use of a Semiconductor Optical Amplifier (SOA) for its ability to control the chirp of the passing optical signal (OCDMA codes) and exploit the SOA ability for dispersion management of a fiber link in an incoherent OCDMA system. Our investigation is done using a 19.5 km long fiber transmission link exposed to different temperatures (20 and 50) ºC using an environmental chamber. By placing the SOA on a transmission site and using it to manipulate the code carriers chirp via SOA bias adjustments, we have shown that this approach can successfully control the overall fiber link dispersion, and can also mitigate the impact on the received OCDMA auto-correlation and it’s FWHM. The experimental data obtained are in a very good agreement with our simulation results

Tunable chromatic dispersion management of optical fibre communication link using SOA

High data rate communication demands the well compensated chromatic dispersion in the optical fibre communication. Generally dispersion compensated fibre (DCF) modules are utilized in the link with known fibre lengths. On the other hand, at ultra high data rates when a new user wants to access the network with a connecting cable of unknown length, automated dispersion compensation technique will ensure the error free communication with much greater flexibility to operate the network. An experiment was carried out to compensate the chromatic dispersion in an optical fibre network by passing the received data signal through an SOA. By controlling the SOA pump current, it was possible to automatically compensate the chromatic dispersion without changing the lengths of DC

Overview of the second order optical nonlinearity in GaN waveguides for use in devices for optical communication

The purpose of this poster is to show how second order nonlinearity of GaN is used in realization of advanced optical devices in telecommunication

Mitigation of temperature induced dispersion in optical fiber on OCDMA auto-correlation

We have experimentally investigated the influence of temperature on the OCDMA auto-correlation recovered after transmission in an optical fiber link when exposed to different temperature settings. The OCDMA system uses two dimensional wavelength-hopping time-spreading (2D-WH/TS) codes based on picosecond multi-wavelength pulses. To the best of our knowledge, we have confirmed for the first time experimentally that a recovered OCDMA auto-correlation will be affected by transmission link temperature changes. Our simulation results are in good agreement with experimental observations. We have also demonstrated that the observed auto-correlation width change can be mitigated by introducing a semiconductor optical amplifier as part of the OCDMA receiver

Management of OCDMA auto-correlation width by chirp manipulation using SOA

In order to preserve the performance of incoherent OCDMA systems it is imperative to maintain the width of the OCDMA auto-correlation function. This can be challenging in OCDMA systems when using multi-wavelength pico-second pulses as code carriers. In this respect, a Semiconductor Optical Amplifier (SOA) was used to control the chirp of OCDMA code carriers before fiber transmission, and the resulting effect on the recovered OCDMA auto-correlation was investigated at the receiving end after a 16 km long transmission in a fiber optic testbed with imperfectly balanced chromatic dispersion (CD

Management of OCDMA auto-correlation function distorted by dispersion effects

Dispersion has very strong detrimental effects on high data rate incoherent transmission systems. Situation gets much worse when data bits become only a few picoseconds long. In this paper we investigate how the dispersion can affect an optical auto-correlation function in optical code division multiple access (OCDMA) systems when data are carried by two-dimensional wavelength-hopping time-spreading codes based on multi-wavelength picosecond pulses. We show how chromatic dispersion and changes of optical fiber temperature can distort the OCDMA auto-correlation. We also demonstrate a simple method for efficient mitigation of these effects