Photonic correlation based on four wave mixing

Kibria, R 2014, Photonic correlation based on four wave mixing, Doctor of Philosophy (PhD), Electrical and Computer Engineering, RMIT University.

Document type: Thesis
Collection: Theses

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Title Photonic correlation based on four wave mixing
Author(s) Kibria, R
Year 2014
Abstract Modern high-performance signal processing applications face constantly increasing processing speeds. The use of photonics potentially offers a much higher bandwidth and faster processing than what can be achieved in the electronic domain. This thesis investigates novel photonic techniques based on optical mixing for performing a correlation, a common signal processing task. The first photonic correlation scheme investigated uses four wave mixing (FWM) in a length of highly nonlinear fibre (HNLF) to mix template or reference wavelengths with a pump wavelength, which has been modulated by an input bit stream in order to produce copies of the input signal at the output idler wavelengths. The idler wavelengths are differentially delayed and summed at a photoreceiver to produce a correlation of the input bit stream and the reference bit pattern. This technique was investigated experimentally and results show that a correlation function is successfully achieved. A significant advantage of this technique compared to previous photonic correlation techniques is that modulation of the pump wavelength allows the “transmitter” to be remotely located, away from the correlation signal processing equipment.

An extension of this technique successfully demonstrated the use of software control of the reference bit pattern using a multi-port photonic signal processor (Waveshaper). This enabled a more versatile form of correlator. True correlation requires the summation of negative signals. This is difficult for optical signals. A novel photonic technique based on FWM, which allows negative accumulation, was proposed for the first time. In this technique, a number of carrier and pump wavelengths are carefully selected such that individual mixing products occur at the same idler wavelength. Subtraction of optical fields at this wavelength can be achieved by changing the relative phase of pump wavelengths by 90 using a Waveshaper optical processor. This novel concept was verified via a simulation using ‘VPItransmissionMaker 9.0’ software. The simulation demonstrated that negative accumulation of optical signals could be achieved for the first time. In summary, novel photonic correlation techniques based on nonlinear optical mixing in optical fibre have been demonstrated and subtraction of optical fields using FWM has been demonstrated for the first time.

Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Electrical and Computer Engineering
Keyword(s) correlation
four wave mixing
microwave Photonics
pattern recognition
highly nonlinear fibre
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Created: Fri, 18 Jul 2014, 11:55:50 EST by Denise Paciocco
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