Management of OCDMA Auto-Correlation Width by Chirp Manipulation Using SOA

Abstract

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).

Application of Semiconductor Optical Amplifier (SOA) in Managing Chirp of Optical Code Division Multiple Access (OCDMA) Code Carriers in Temperature Affected Fibre Link

“…In this configuration, we had to use a picosecond optical pulse called a holding beam (OP/HB) synchronized with the OCDMA auto-correlation at the SOA input to be able to demonstrate that the OCDMA auto-correlation that was broadened by the fibre chromatic dispersion can be continuously 'compressed'. In [20], we reported the use of an SOA on the transmitter site (right after the OCDMA encoder) to compensate the OCDMA auto-correlation broadening due to the fibre chromatic dispersion (D CD > 0), we observed on the OCDMA receiver site by controlling the chirp of the individual multi-wavelength OCDMA code carriers spread over a bit period before the code is launched into a fibre link.…”

“…By following [20], we now develop a mathematical model for describing the effect of the code carriers' chirp and temperature induced dispersion changes in the fibre transmission link on the OCDMA auto-correlation envelope. Because we have used the same OCDMA hardware, we used in [20], the chirp value C = 2.36 at the OCDMA encoder output (point A, Figure 1) will be considered to be the same for the purpose of this investigation.…”

“…In [19], it was experimentally demonstrated that the influence of the fibre link temperature on the recovered OCDMA auto-correlation could be mitigated by introducing an SOA as part of the OCDMA receiver. In [20], an SOA that was located at the transmission end was used to control the chirp of OCDMA code carriers to mitigate the effect of CD on the OCDMA auto-correlation width changes at room temperature.…”

Chirp Management in Communication Systems with Picosecond Data Carriers Using a Single SOA

“…The chirp can also result from changes of the refractive index associated with variations of carrier densities. The effect of chirp C on the recovered OCDMA auto-correlation envelope SL(t) can be described as [1]:…”

“…The same is true when using ultra-short multiwavelength OCDMA code carriers in Optical Code Division Multi Access (OCDMA) systems. Here having a tunable dispersion control is highly desirable [1,2,3,4]. As shown in [4], even a meagre 50 m of SMF-28 fiber mismatch from the fully dispersion compensation state would lead to a 1 dB power penalty.…”