This Letter reports a lead (II) ion sensor composed of a tapered multimode fibre (MMF) coated with chitosan. The diameter and length of the tapered fibre region is 20 µm and 1 cm, respectively. Tapered MMF is used because it is more flexible and compact compared with plastic clad silica. Chitosan is chosen as the sensing layer because it can absorb heavy metal ions due to its unique properties as polyelectrolyte and chelating agent. The refractive index of the chitosan layer changes as it absorbs lead (II) ion and this leads to an increase in the absorbance measured by the spectrophotometer. This is tested by immersing the sensor in a solution that contains lead (II) ion with different concentrations, from 0.2 to 1 ppm. The results show that the absorbance measured by the spectrophotometer increased as the concentration of the lead (II) ion increased. The sensor's average sensitivity is measured as 40.554 abs/ppm. This sensor is simpler compared with surface plasmon resonance‐based lead (II) ion sensor because it does not require metal coating prior to the sensing layer coating.

We report on the optical properties of Bi-doped phosphosilicate fiber. The fiber with a core and a clad diameter of 7.75 µm and 125 µm, respectively, is fabricated in-house using the modified chemical vapor deposition (MCVD) with in-situ solution doping technique. The spectroscopic properties of the fabricated fiber are characterized in terms of absorption, emission and lifetime. The lifetime decay is measured to be 800 µs; indicating a good potential optical amplification in the range of 1300 to 1500 nm. A Bismuth-doped fiber amplifier (BDFA) operating within the O-band region was successfully demonstrated. At 1340 nm, a 14.8 dB gain is achieved with 300 mW pumping power.

We demonstrate a multiwavelength Brillouin Erbium fiber laser with double channel spacing operating at room temperature using a hybrid linear-ring cavity. 7 simultaneous lines with 0.175nm line spacing using both a 100mW pump at 980nm and a 4dBm Brillouin pump are achieved by circulating the odd-order Stokes signals in a 7km long single mode fiber based sub-ring cavity, allowing for the formation of even-order Stokes signals at the output.

This paper presented the fabrication and characterization of a Bismuth-doped fiber with Phosphorus. The preform was fabricated using conventional modified chemical vapour deposition and in-situ solution doping. The drawn fiber was then characterized in terms of its absorption and emission spectrum. The preliminary results show that the 1 m length Bismuth-doped fiber has an emission spectrum at the broad range of 1300 nm to 1500 nm using forward pumping configuration. Amplification can be achieved by using longer fiber length and different pumping configuration. The Bismuth-doped fiber could potentially be used as a fiber amplifier in a GPON network, which supports the wavelength of 1310 nm (uplink) and 1490 nm (downlink).

We have investigated the self-lasing effect of the linear multiwavelength Brillouin-Erbium fiber laser with different tunable bandpass filter's bandwidth. Two 3dB bandwidth of 1 nm and 3 nm filter were used in this study. The experimental results show that the width of the TBF bandwidth plays an important role in shaping the self-lasing effect. By using the tunable bandpass filter with a broader bandwidth, the self-lasing effect can be suppressed efficiently thus producing higher Brillouin Stokes lines. At 0 dBm Brillouin pump power, up to 11 stable output laser channels can be obtained with the utilization of the 3 nm TBF as compared to only 5 output channels with the utilization of 1 nm TBF.

A simple multiwavelength source based on spectral slicing of supercontinuum is demonstrated. The spectral slicing technique using Sagnac loop mirror allows the generation of broad multiwavelength source extending from 1320 nm to 1750 nm.