## 2 Experimental Setup  
The experimental setup that we used for our investigation is shown in Figure 1. Here, the ps ML Laser produces a 1.8 ps single wavelength (1545 nm) optical clock at OC-48 rate (bit-width equal to \(\sim\)400 ps), which is then passed through an optical supercontinuum generator (OSG) by PriTel, Inc. (Naperville, IL, USA). The OSG consists of a high-power erbium doped fiber amplifier and dispersion decreasing fiber (DDF). The optical clock from the ps ML Laser that was centered at 1545 nm after the amplification by an 18 dBm erbium doped fibre amplifier (EDFA) is injected into approximately a 1 km long DDF. This way, a 3.2 nm wide optical supercontinuum is generated in a spectral region of 1550-1553.2 nm. The supercontinuum is then spectrally sliced by an OCDMA encoder (OKI Industries, Saitama, Japan), which is based on four FBGs (central frequencies are: \(\lambda_{1}\) = 1551.72 nm, \(\lambda_{2}\) = 1550.92 nm, \(\lambda_{3}\) = 1552.52 nm, \(\lambda_{4}\) = 1550.12 nm) matching the 100 GHz ITU grid. The physical separation of individual FBGs is such that the encoder generates a following 2D-WH/TS OCDMA code: (1-\(\lambda_{2}\), 21-\(\lambda_{4}\), 24-\(\lambda_{1}\), 39-\(\lambda_{3}\)). Here, the integer number leading \(\lambda_{i}\) represents the order of the time slot (called a chip) containing the carrier \(\lambda_{i}\) within the 400 ps long bit-width. This OCDMA code is then amplified by 15 dBm EDFA-1 and is transmitted through a 19.5 km long fibre spool that is located inside of the environmental chamber (SM-32C from Thermatron Industries, Holland, MI, USA). At the receiving end, an OCDMA auto-correlation is recovered from the received signal by an OCDMA decoder (OKI Industries) that is matched to the OCDMA encoder. In this process, the decoder removes all delays that are imposed on individual code carriers by the encoder [21]. The result is an OCDMA auto-correlation peak, i.e., which represents the received data. This is illustrated in Figure 2. To compensate for the code carriers' optical attenuation resulting from the fibre link attenuation, and also for the losses during the OCDMA auto-correlation recovery by the decoder, the resulted signal is amplified by a 15 dBm EDFA-2. For longer transmission distances, when the transmitted signal suffers more attenuation losses, an EDFA may be required before the OCDMA decoder. In our investigation, the decoded signal was then analysed using an optical spectrum analyser (OSA--Agilent 86146B, Agilent Technologies, Santa Clara, CA, USA) and oscilloscope, (OSC--Agilent Infiniium DCA-J 86100 Cwith a 64 GHz optical sampling head, Agilent Technologies, Santa Clara, CA, USA). For future applications, to avoid the need for high bandwidth electronics, we assume us  
Figure 1: Experimental setup for the chirp control investigation by SOA at a transmitter site. ps ML Laser: picosecond mode locked laser; EDFA: erbium doped fibre amplifier; DDF: dispersion decreasing fibre; FBG: fibre Bragg gratings; DCF: dispersion compensating fibre; SOA: semiconductor optical amplifier; OSA: optical spectrum analyser; OSC: oscilloscope. front of the 2D-WH/TS OCDMA decoder that is similar to one demonstrated in [8]. This hard-limiter would be based on a picosecond all-optical time gating, followed by low-bandwidth electronics. To study the effect of temperature on the transmitted OCDMA codes, the 19.5 km link was CD compensated at room temperature \(T\) = 20 \({}^{\circ}\)C using a commercially available dispersion compensating module DCF. In our investigations, the fibre link temperature will be varied from 20 \({}^{\circ}\)C to 50 \({}^{\circ}\)C. As a result, the code carriers will be affected by these temperature changes due to fibre refraction index temperature dependency [19]. The temperature induced dispersion coefficient \(D_{\rm T}\) of optical fibre is negative.