Syamsuri Yaakob

All-optical generation of a 21 GHz microwave carrier by incorporating a double-Brillouin frequency shifter

An all-optical generation of a microwave carrier at 21 GHz that incorporates a double-Brillouin frequency shifter is presented. The frequency shift of approximately 21 GHz is achieved by generating the second-order Brillouin Stokes signal from the Brillouin pump. This is accomplished through the circulation and isolation of its first-order Stokes signal in the optical fiber. The Brillouin pump signal is heterodyned with its second-order Brillouin Stokes signal at a high-speed photodetector, and the output beating frequency is equal to the offset between these two signals. The generated microwave carrier is measured at 21.3968 GHz, and the carrier phase noise as low as -58.67 dBc/Hz is achieved.

Live HD video transmission using 40GHz radio over fibre downlink system

40GHz radio over fibre (ROF) downlink system is constructed to demonstrate HD video transmission capability using the hybrid optical and wireless system. The dual-sideband optical carrier suppression (DSB-OCS) technique is used in conjunction with the minimum transmission bias (MiTB) to generate optical millimetre wave signal by utilizing a dual electrode Mach-Zehnder modulator (DE-MZM). A baseband high definition (HD) video signal is modulated into the system via a second MZM. The signal is distributed to a remote antenna unit (RAU) using a 20km optical fibre, then transmitted wirelessly to a customer premise equipment (CPE) located at 5m away. The results show that the HD video is successfully transmitted over the error free 40GHz ROF downlink system.

Internally generated 21.6-GHz millimeter wave based on brillouin fiber laser

An all-optically generated millimeter wave carrier at 21.67 GHz is experimentally achieved. This frequency is realized when two consecutively generated laser wavelength are heterodyned on the 60 GHz high-speed photodiode. The mixing between the Brillouin pump and the second-order Stokes wavelengths is spaced by 1.7 nm. This spacing, which is doubled from inherently generated Stokes shift, is accomplished through the isolated circulation of the first order Stokes wave in the double Brillouin Stokes shifter built with 25-km single mode fiber. The generated millimeter carrier is measured at 21.68 GHz, and its carrier phase noise and threshold power are −58.67 dBc/Hz and 19 mw of Brillouin pump power respectively.

Effect of Laser Bias Current to the Third Order Intermodulation in the Radio over Fibre System

Third order intermodulation (IM3) can cause non-linearity effects which result in interference and crosstalk between the subcarriers in radio over fibre (ROF) transmissions. This paper presents the experimental results of the effect of varying the magnitude of the laser bias current on the IM3 in an ROF system with direct modulation. We also investigate the behaviour of the system spurious free dynamic range (SFDR) with the bias current variation. The results show that there will be an optimum bias current range for a given range of the radio frequency (RF) input power in order to minimise the IM3 effect and obtain the best possible SFDR for the system

Flexible 16

To achieve flexible packet routing in a time wavelength-division multiplexing passive optical network (PON) architecture, most proposed systems use a tunable transceiver in the optical line terminal (OLT). The tunable transceiver is attractive for use in a PON system because it is able to broadcast and multicast packets within the entire PON system, being limited only to a single PON link. The proposed all-optical packet routing (AOPR) module was designed to incorporate a fixed-type wavelength OLT transmitter with a continuous-wave pump probe signal module. The design of the module is based on the ALL-ON method to support all broadcast signals, which replaces the wavelength tuning feature in the tunable OLT transmitter. The proposed architecture was designed using the multicasting cross-gain modulation (XGM) method. In this proposed design, the XGM function of the OLT system becomes a part of the AOPR OLT transmitter. The arrangement of this design aims to generate single or multiple wavelengths in a downstream direction in each OLT PON port. The measurement results revealed that the proposed system can handle a total of 160-Gb/s broadcast downstream bandwidth to serve 16 PON links using λ with a maximum of 2048 users.

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This paper presents the evaluation of radio over fibre (ROF) capability with electroabsorption modulator (EAM) as a downlink photodetector (PD) and uplink radio frequency (RF) modulator. The results show that the EAM device has potential to be adopted as the transceiver at the remote antenna unit (RAU) for the system. The 130 m ROF system with biased EAM is capable to obtain a symmetrical WLAN 802.11a data rate of 18 Mbps with laser diode output power of 8.7 dBm.

10-Gb/s All-Optical Broadcast and Multicast TWDM Passive Optical Network

This work involves in transmitting of intermediate frequency (IF) signal over fiber utilizing photonics frequency conversion, which, the main focus is the development of optical front-end receiver. The system uses photodiode and heterojunction bipolar transistor (HBT) to detect and up-convert the received IF modulated optical signal. The photodiode (PD) and HBT are very useful devices for photonics frequency conversion technique with high internal gain and frequency up conversion of optical signal. Through simulation, the optimum device parameters and characteristics were determined. The system was implemented to detect a 0.4 GHz of IF carriers signal and up-converted to 3.4 GHz of radio frequency (RF) signal. The optimum conversion gain that has been obtained from the measurement and simulation were about -11 dB and -8 dB, respectively, at V BE = 0.7 V, P LO = 4 dBm, and -25 dBm of IF optical input power. The system has been practically demonstrated and shown to agree reasonably well with both the theory and simulation. This article also refers to some recent patents on frequency conversion techniq.

Adopting Electroabsorption Modulator for the WLAN 802.11a Radio over Fibre System

All-optical signal generation using a 10 GHz radio frequency (RF) based on stimulated Brillouin scattering (SBS) technique has been integrated with front-end optical receiver utilizing heterojunction bipolar transistor (HBT) mixer. The proposed downlink remote optical local oscillator (ROLO) for radio over fiber (RoF) system was demonstrated at up to 40 GHz millimeter-wave (mm-wave) carrier. It has been discovered that the proposed RoF-ROLO system is useful to reduce the dispersion effect that usually limits the mm-wave RoF system performance. In addition, based on simulation study about -39.3 dBm of output power was achieved at up-converted frequency of 42.4 GHz by fixing the optical carrier input power at -10 dBm.

Frequency up-conversion technique for radio over fiber (RoF) remote antenna unit configuration

The dual sideband optical carrier suppression (DSB-OCS) technique is characterised for its performance in order to be used as a carrier for 1.25Gbps OOK signal in the 40GHz radio over fibre (ROF) system. A dual electrode Mach-Zehnder modulator (DE-MZM) and the minimum transmission bias (MiTB) technique are employed to build the system. The results show that, a 40GHz carrier is successfully generated with the amplitude up to -29dBm and SNR of 35dB. Finally, an error free 40GHz ROF system is constructed with almost no penalty between the back to back and 20km fibre for a BER of 10-9.

Front-end optical receiver utilizing remote local oscillator for radio over fiber system

A small signal analysis was performed on a specific 0.2 mum HEMT device to study the impact of multiple-gated layout towards the gain and cut-off frequency performance. The characterization process was using on-wafer measurement technique to AlGaAs/InGaAs HEMT devices which consisted of three types of layouts of various gate finger numbers and widths. The devices were biased at the optimum basing voltage obtained from DC characterization performed previously. From the result, it was observed that the device with higher number of gates exhibited higher gain only at low frequency, while at higher frequency the gain dropped significantly. This significant drop in gain was due to the increase of the gate-source capacitance in the device, thus leading to a reduction of the device cut-off frequency. The experimental findings were strongly supported by simulation which was based on related theory on the layout dimension contribution.