M. Z. Jamaludin

Dual-function remotely-pumped Erbium-doped fiber amplifier: Loss and dispersion compensator

An efficient Erbium-doped fiber amplifier configured in doublepass amplification scheme with chirped fiber Bragg grating as the reflector is presented in this paper. The proposed amplifier architecture is optimized and designed to work under consideration of low pump powers for remotely-pumped applications. The chirped fiber Bragg grating is used to reflect the amplified signal back to the Erbium-doped fiber and at the same time to compensate the effect of fiber dispersion. The proposed amplifier architecture is able to maintain gain of higher than 20 dB for small signals less than -23 dBm with 10 mW pump power only. The integrated function of loss and dispersion compensator in single black box is an attractive solution to be used as pre-amplifier.

Characteristics of multiwavelength L-band Brillouin–Raman fiber laser under forward and backward pumped environment

We experimentally investigate the performance of L-band multiwavelength Brillouin-Raman fiber laser (MBRFL) under forward and backward pumped environments utilizing a linear cavity. A short length of 1.18 km dispersion compensating fiber is used as a nonlinear gain medium for both Brillouin and Raman gain. Experimental results indicate that the gain in the copumped laser configuration is higher than the gain in the counterpumped configuration. A stable and constant number of Brillouin Stokes lines up to 23 Stokes, with channel spacing of 0.08 nm and more than 20 dB of optical signal to noise ratio, can be generated as well as tuning over 20 nm in the L-band region from 1570 to 1590 nm. The laser generating the Brillouin Stokes lines exhibits flat amplitude bandwidth and high average output power of 0.8 and 1.6 dBm for the copropagation and counterpropagation pumps, respectively. Moreover, the tuning range bandwidth of the MBRFL can be predicted from the oscillated Brillouin pump gain profile.

Pressure sensing utilizing linear cavity erbium-doped fiber laser

In this paper, we report a fiber laser pressure sensor based on linear cavity erbium-doped fiber laser. The fiber laser structure comprises of an erbium-doped fiber amplifier, a circulator, an optical coupler and a fiber Bragg grating (FBG) which acts simultaneously as a lasing wavelength selecting components as well as a pressure sensor. The FBG is fitted to the shock tube where the pressure is applied. The fiber laser pressure sensor has a low threshold power of 7 mW, an output power of 2.28 mW and an optical signal to noise ratio over 55 dB. The proposed fiber laser sensor is expected to be an attractive choice for long-distance pressure monitoring.

High gain double-pass L-band EDFA with dispersion compensation as feedback loop

We demonstrate an efficient double-pass L-band erbium-doped fiber amplifier (EDFA) incorporating chirped fiber Bragg grating (CFBG). The amplifier structure exploits the characteristics of CFBG to reflect the amplified signal back into the gain medium, filter out the recycled forward amplified spontaneous emission and block the residual 1480 nm pump power. The amplifier configuration has high gain and low noise figures as compared to double-pass EDFA using broadband mirror. The demonstrated amplifier has gain of more than 48 dB and low noise figure of less than 4 dB at low input signal power of −40 dBm.

Third party security audit procedure for network environment

Defending ones systems and networks is an arduous task since computing systems are vulnerable to unauthorized access. Most organizations and companies rely totally on firewalls for network security. Support of firewall installations requires a firewall and network environment audit that is governed by the organizations security policy. The paper describes a security audit procedure based on network posture vulnerabilities. The scope of the work covers some discussion on network perimeter defence and suggestions for the audit procedure.Defending ones systems and networks is an arduous task since computing systems are vulnerable to unauthorized access. Most organizations and companies rely totally on firewalls for network security. Support of firewall installations requires a firewall and network environment audit that is governed by the organizations security policy. The paper describes a security audit procedure based on network posture vulnerabilities. The scope of the work covers some discussion on network perimeter defence and suggestions for the audit procedure.

Radio frequency radiation evaluation of transmitting devices in VHF/UHF band

This paper describes an evaluation of the radio frequency radiation (RFR) from transmitting devices in the VHF/UHF band. The RFR readings are then verified with the guidelines made by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) which was recommended by the International Telecommunication Union (ITU). The scope of this study is to gather and evaluate information on possible exposure of the general public at public accessible area around Klang Valley, Malaysia due to radio frequency radiation in the VHF/UHF band. The location was chosen based on highly populated areas and the distance from the TV and radio transmitters. A total of ten sites were chosen to be evaluated. Two types of measurements were conducted at each site, which are broadband and narrowband measurements. The narrowband measurements were carried out at the point where broadband measurement gives the highest reading. Data from a spectrum analyzer is then analyzed to determine the exposure level. Through analysis; it was found that the exposure level is well below the safety guidelines. Therefore, RFR in all ten sites conform to the ICNIRP guidelines.

Enhancement of Brillouin gain efficiency in multiwavelength L-band BEFL by utilizing bi-directional Brillouin pump amplification

Enhancement of Brillouin gain efficiency in a multiwavelength L-band Brillouin-erbium comb fiber laser is presented. In this laser architecture, bi-directional amplification of the injected Brillouin pump signal within the erbium gain medium, before entering the single-mode fiber was utilized. Owing to this bi-directional pre-amplification of the Brillouin pump power, the requirement of a long single-mode fiber to increase the Brillouin gain efficiency was overcome. The shot length of a single-mode fiber was utilized to achieve a high number of output channels with high peak power. Up to 25 output channels with a constant wavelength separation of 0.089 nm were achieved at 170 mW of 1480 nm pump power and 0.54 mW of Brillouin pump power in a 0.5 km short single-mode fiber.

IPQit: An internet simulation kit based on NS2

Network Simulator 2 (NS2) is one of the more used network simulator across the globe. However, NS2 is often associated with a steep learning curve for new users. Therefore an effort to automate the process of using NS2 using a graphical user interface (GUI) has been initiated. The paper describes the tool kit GUI known as Internet protocol quality of services toolkit (IPQit). It provides an easy to use GUI for both network topology creation and post-processing of NS2. Its usage is mainly intended for educational purposes. It supports quality of services (QoS) technology.

L-Band Multi-Wavelength Brillouin–Raman Fiber Laser with 20-GHz Channel Spacing

Abstract A tunable multi-wavelength L-band Brillouin–Raman fiber laser with a 20-GHz channel spacing utilizing bidirectional ring cavity is proposed and experimentally investigated. The laser employs a co-pumped dispersion compensating fiber as a gain medium for both Brillouin and Raman gains. With a Raman pump of 425 mW, the laser system can generate up to 12 double-spaced Brillouin Stokes signals. This simple laser configuration provides stable Brillouin Stokes signals in the absence of self-lasing cavity modes with a tuning range exceeding 35 nm without using any filtering mechanism. The Stokes signals have more than 20 dB of optical signal-to-noise ratio.

Analysis of real-time multiple source video streaming via wireless 5.8 GHz for intelligent traffic management system

This paper evaluates the performance of live compressed motion image transmission in coherence with the development of the multiple video streaming and compression (multiple-VSCS) software, as applied for the intelligent traffic management system. Motion images of multiple sources are captured, jointly compressed and streamed real time via utilization of the 5.8 GHz OFDM outdoor wireless LAN network. Experiments were performed and analyzed to ascertain the reliability and potency of this application with improved bitstream rates as low as 50 kbps and compression ratio rates as high as 1800:1, under various compression parameters settings as well as different video formats. This paper also includes performance analysis of video stream rates with comparison into varying compression formats and quantization factors retrospective to quality of service (QoS). Projections were also performed as behavioral study on the effects of the available bandwidth with increased video capture sources and streaming processes.