Optical Fiber Biosensor toward E-coli Bacterial Detection on the Pollutant Water

In this study, Zinc oxide (ZnO) nanorods based fiber optic biosensor has been reported for rapid and sensitive detection of Escherichia Coli (E-coli). A thin layer of Gold nanoparticles (Au) (around 50 nm) is coated on the tip of a multimode plastic optical fiber.  ZnO Nanorods are grown on Au layer thorough hydrothermal technique. This sensor showed a very fast response within the first 10 second of contacting the present of polluted water with E-coli Different concentrations of E. coli from (1000 to 4000 CFU/ml) have been tested and a sharp trend of sensitivity was observed. This sensing platform shows promising potential for regular water and food quality monitoring of various pathogenic microorganisms

Supercontinuum generation from a sub-megahertz repetition rate femtosecond pulses based on nonlinear polarization rotation technique

A means of supercontinuum (SC) generation is proposed and demonstrated, using femtosecond mode-locked pulses with sub-megahertz repetition rate based on the nonlinear polarization rotation technique. Total cavity length is approximately 522 m, which includes an additional 500 m single mode fiber (SMF) and the fundamental repetition rate obtained is 404.5 kHz. The mode-locked spectrum has a central wavelength of approximately 1600 nm and a 3 dB bandwidth of 16 nm, which falls within the L-band region. The threshold power for the mode-locked operation is achieved at approximately 52 mW. At pump power of 74 mW, the measured pulse width, pulse energy, and average output power are 70 fs, 18.3 nJ and 7.4 mW respectively. The generated pulses are amplified by a 72.44 mW erbium-doped fiber amplifier before being injected into a 100 m long highly non-linear fiber as the nonlinear medium to generate the SC spectrum. The obtained SC spectrum spans from 1250 nm to more than 1700 nm, with bandwidths of 450 nm at a −70 dBm output power level. For comparison purpose, the 500 m SMF is removed from the setup and similar measurements are then repeated for this case

Flat-gain wide-band erbium doped fiber amplifier by combining two difference doped fibers

A new erbium-doped fibre amplifier (EDFA) is demonstrated using a combination of newly developed Erbium Zirconia co-doped fiber (Zr-EDF) and the commercial silica-based Erbium-doped fiber (Si-EDF) as the gain medium. Both fibers have a very high concentration of erbium ion. A compact amplifier operating in C-band region is firstly reported using a double-pass configuration. It is shown that average gains of the proposed Zr-EDF amplifier are obtained at approximately 18 dB with a gain variation of +-2 dB within C-band region. A flat-gain and wide band operation is achieved by configuring the amplifier in two stages comprising a 2 m long Zr-EDF and 9 m long Si-EDF optimised for C- and L-band operations, respectively, in a double-pass parallel configuration. A chirp fibre Bragg grating (CFBG) is used in both stages to ensure double propagation of the signal and thus to increase the attainable gain in both C- and L-band regions. At an input signal power of 0 dBm, a flat gain of 15 dB is achieved with a gain variation of less than 0.5 dB within a wide wavelength range from 1530 to 1605 nm. The corresponding noise figure varies from 6.2 to 10.8 dB within this wavelength regio

Graphene Nano-, Micro-and Macro-Photonics

ABSTRACT Graphene has already become an established medium for novel photonic devices and their applications. In some cases, e.g. the use of graphene as a non-linear medium with saturable absorption properties, it is experimentally convenient to use the readily available form that is known as graphene oxide. Moreover, technological and scientific developments that are advancing control of the properties of graphene for electronic applications are also likely to be applicable in photonic and optoelectronic devices. This presentation will review research in the field of graphene photonics across the world. It will address, in particular, its application as a saturable absorber, e.g. for pulsed operation of fibre lasers -as well as work on materials characterisation of deposited graphene films. Patterning of graphene films with precision at the microand nano-scales will be an important requirement -and will be considered in this presentation

Bismuth-based erbium-doped fiber as a gain medium for L-band amplification and Brillouin fiber laser

Bismuth-based erbium-doped fiber (Bi-EDF) is demonstrated as an alternative medium for optical amplification and nonlinear applications. The bismuth glass host provides the opportunity to be doped heavily with erbium ions to allow a compact optical amplifier design. The bismuth-based erbium-doped fiber amplifier (Bi-EDFA) is demonstrated to operate at wavelength region from 1570 to 1620 nm using only a 215 cm long of gain medium. The maximum gain of 15.8 dB is obtained at signal wavelength of 1610 nm with the corresponding noise figure of about 6.3 dB. A multi-wavelength laser comb is also demonstrated using a stimulated Brillouin scattering in the 215 cm long Bi-EDF assisted by the 1480 nm pumping. The laser generates more than 40 lines of optical comb with a line spacing of approximately 0.08 at 1612.5 nm region using 152 mW of 1480 nm pump power

Fabrication and characterization of high order filter based on resonance in hybrid multi-knots microfiber structure

This work proposes a novel design of a hybrid microfiber resonator which can be used as a band-pass and band-stop filter in various applications such as fiber lasers. The structure comprises of two microfiber knot resonators with different sizes which are surrounded by a semi-loop structure with one input and two output ports. Utilization of the Vernier effect in the proposed structure showed an enhancement of the free spectral range (FSR). The finesse has increased by a factor of three compared to a single knot providing a sharper roll-off. The filter bandwidth is adjustable as a result of the manipulation of the coupling length and rings' radii. The performance of the device is explained theoretically using transfer matrix analysis

Realization of spectral tunable filter based on thermal effect in microfiber structure

This paper demonstrates a new approach for tuning the extinction ratio of a complex microfiber structure output using thermal effect. The microfiber filter device comprises of a microfiber Mach-Zehnder interferometer followed a knot structure, where temperature is controlled by a DC current applied to a copper wire placed inside the knot. This enables electrical tuning, where applying electrical current increases the temperature and affects the optical path. The change of temperature facilitates the fine tuning of the resonance output spectrum. From the experiment, it was observed that the extinction ratio of the output comb spectrum can be controlled within 2 dB to 10 dB by varying the current rating from 0 A to 1.22 A

Demonstration of a Periodic Passband Filter Based on Coupled Microfiber Knots

In this letter, a periodical passband filter based microfiber structure is proposed. The structure is made of successive microfiber knot resonators. The periodical spectral filtering is a result of superposition of the uncoupled modes that belong to the individual microfiber knots and coupling induced resonant wavelength shift. This letter demonstrates the experimental investigation of the thermal effect on the spectral modulation of the structure. The proposed resonator consists of two knots with radii 460.01 and 230 μm, which are knitted successively, in a column. This results in a periodic spectrum with 720-pm passband, 425-pm stopband, and a suppression ratio of 5.2 dB. Increasing the optical path, using a hot metal bar with a temperature of 30° close to the big knot, the periodic passband filter switches to all pass filter with a free spectral range of 1150 pm and quality factor 6000. This letter as well demonstrates experimentally how to enhance passband and stopband widths through decreasing the knot's radii as well as increasing the number of knots. Compatibility of this structure with single-mode fiber systems makes it easy to be used as noise filtering in telecommunication and fiber lasers

Dual wavelength high power double-clad erbium/ytterbium-doped fiber laser

A dual wavelength high power double-clad erbium/ytterbium-doped fiber laser with a narrowest spacing of 0.4 nm and a M-2 value of close to unity is presented in the region of 1565 nm. This result can be realized with a significant improvement of the mode competition problem using a loop mirror as a comb filter. The wavelength region can also be varied using polarization controllers in the loop mirror. This dual-wavelength fiber laser with side mode suppression ratio (SMSR) of 40 dB is quite stable, and the output power variance is as low as 0.46 dB